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5.0L SEFI EEC IV TESTING 1987 Lincoln Mark VII 1987 Computerized Engine Controls FORD MOTOR CO. EEC IV DIAGNOSIS & TESTING 5.0L SEFI DIAGNOSIS & TESTING DIAGNOSTIC PROCEDURE This diagnostic procedure is used to test and service the EEC-IV system. It is divided into 2 test formats: QUICK TEST, a functional system test, and CIRCUIT TESTS, a number of specific circuit and component tests. To test and service EEC-IV system, perform the QUICK TEST first. If vehicle passes KEY ON/ENGINE OFF (KOEO), KEY ON/ENGINE RUNNING (KOER), and CONTINUOUS SELF-TESTS of QUICK TEST without running any CIRCUIT TESTS, the EEC-IV system is okay. Problem exists somewhere else besides the EEC-IV system. If QUICK TEST fails, perform only those tests that are specified by the failed step. TEST CONNECTOR LOCATIONS All Mustang models have SELF-TEST connector on left rear corner of engine compartment. On Continental and Mark VII models, the SELF-TEST connector is on the right side of the engine compartment, near firewall. The Crown Victoria, Grand Marquis and Town Car, have the SELF-TEST connector on left fender apron, above wheelwell (near fuel pump relay). PREPARATION FOR TESTING Correct test results for system are dependent on the correct operation of several related non-EEC components and systems. All non- EEC problems should be corrected before attempting to diagnose the EEC system. Before hooking up any equipment to diagnose the EEC system, make the following checks: * Verify condition of air cleaner and air ducting. * Check all vacuum hoses for leaks, restrictions, and proper routing. * Check the EEC-IV system wiring harness electrical connections for corrosion, bent or broken pins, loose wires or terminals, and proper routing. * Check the ECA, sensors and actuators for physical damage. * Perform all necessary safety precautions to prevent personal injury or vehicle damage. * Set parking brake and place shift lever in "P" for automatic transmissions, and Neutral for manual transmissions. DO NOT move shift lever during testing unless specifically directed to do so. * Turn off all lights and accessories, and make sure that vehicle doors are closed when making voltage or resistance readings. * Check and correct coolant level.

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Page 1: 5.0L SEFI EEC IV TESTING - Carolina Broncos Forums - … - EFI - 5.0l eec iv testing.pdf · 5.0L SEFI EEC IV TESTING 1987 Lincoln Mark VII 1987 Computerized Engine Controls FORD MOTOR

�5.0L SEFI EEC IV TESTING

�1987 Lincoln Mark VII

1987 Computerized Engine Controls FORD MOTOR CO. EEC IV DIAGNOSIS & TESTING

5.0L SEFI

DIAGNOSIS & TESTING

DIAGNOSTIC PROCEDURE

This diagnostic procedure is used to test and service theEEC-IV system. It is divided into 2 test formats: QUICK TEST, afunctional system test, and CIRCUIT TESTS, a number of specificcircuit and component tests. To test and service EEC-IV system,perform the QUICK TEST first. If vehicle passes KEY ON/ENGINE OFF (KOEO), KEY ON/ENGINERUNNING (KOER), and CONTINUOUS SELF-TESTS of QUICK TEST withoutrunning any CIRCUIT TESTS, the EEC-IV system is okay. Problem existssomewhere else besides the EEC-IV system. If QUICK TEST fails, performonly those tests that are specified by the failed step.

TEST CONNECTOR LOCATIONS

All Mustang models have SELF-TEST connector on left rearcorner of engine compartment. On Continental and Mark VII models, the SELF-TEST connectoris on the right side of the engine compartment, near firewall. TheCrown Victoria, Grand Marquis and Town Car, have the SELF-TESTconnector on left fender apron, above wheelwell (near fuel pumprelay).

PREPARATION FOR TESTING

Correct test results for system are dependent on the correctoperation of several related non-EEC components and systems. All non-EEC problems should be corrected before attempting to diagnose the EECsystem. Before hooking up any equipment to diagnose the EEC system,make the following checks:

* Verify condition of air cleaner and air ducting. * Check all vacuum hoses for leaks, restrictions, and proper routing. * Check the EEC-IV system wiring harness electrical connections for corrosion, bent or broken pins, loose wires or terminals, and proper routing. * Check the ECA, sensors and actuators for physical damage.

* Perform all necessary safety precautions to prevent personal injury or vehicle damage. * Set parking brake and place shift lever in "P" for automatic transmissions, and Neutral for manual transmissions. DO NOT move shift lever during testing unless specifically directed to do so. * Turn off all lights and accessories, and make sure that vehicle doors are closed when making voltage or resistance readings.

* Check and correct coolant level.

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* Start engine and idle until upper radiator hose is hot and pressurized and throttle is off fast idle. Check for leaks around exhaust manifold, exhaust gas oxygen sensor, and vacuum hose connections. * Turn ignition key off. Service items as required, then go to EQUIPMENT HOOK-UP.

NOTE: If engine will not start, starts but stalls, idles rough or runs rough, go through KEY ON/ENGINE OFF SELF-TEST (KOEO). If any of the above conditions are still present after a code 11 in the KOEO SELF-TEST, go to CIRCUIT TEST A for a no start condition. If engine stalls or runs rough, go to DIAGNOSIS BY SYMPTOM TEST.

EQUIPMENT HOOK-UP

Analog Volt/Ohm Meter (VOM) 1) Turn ignition key off. Connect jumper wire from Self-TestInput (STI) pigtail to pin No. 2 (Signal Return) on SELF-TESTconnector. Set VOM at 0-15V DC range and connect positive lead of VOMto positive battery terminal. 2) Connect negative VOM lead to pin No. 4 (STO) on SELF-TESTconnector. See Fig. 1. Connect timing light, then go to KEY ON/ENGINEOFF (KOEO) SELF-TEST.

STAR Tester Turn ignition key off. Connect color coded adapter cableleads to diagnostic tester. Connect adapter cable’s 2 serviceconnectors to vehicle’s SELF-TEST connectors. Connect timing light,then go to KEY ON/ENGINE OFF (KOEO) SELF-TEST.

NOTE: Diagnostic tester hook-up instructions apply to STAR tester only. If other than STAR tester is being used, follow diagnostic tester manufacturer’s instructions.

Fig. 1: Equipment Hook-UpCourtesy of Ford Motor Co.

TEST EQUIPMENT

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The following equipment is recommended to diagnose and testEEC-IV system. Some equipment is REQUIRED to perform tests. DO NOTattempt to test this system without proper equipment. Damage tovehicle components will result if improper equipment is used.

* The Self-Test Automatic Read-Out (STAR) Diagnostic Tester (Rotunda 007 00004) is recommended but not required. It is specially built for the EEC-IV system and is used to display, as numerals, the 2-digit service codes that are programmed into the control module.

* Analog Volt/Ohmmeter (VOM) with 0-20V DC range. This can be used as an alternate to diagnostic tester. * Digital Volt/Ohmmeter (DVOM) with minimum 10-megaohm input impedance.

* Breakout Box (Rotunda 014-00322). This is a jumper wire assembly which connects between the vehicle harness and the ECA. The breakout box is REQUIRED to perform certain tests on the system. Ford Motor Co. specifically states that using the probe from a DVOM will cause PERMANENT DAMAGE to the ECA 60- pin connector. "Test Pin(s) No." as called out in CIRCUIT TESTS refers to test pin number(s) on breakout box. Once the breakout box has been installed during a test sequence, it may be left connected for the remainder of the test.

* Vacuum gauge with 0-30 in. Hg range and resolution (unit on scale) of 1 in. Hg. * Tachometer with 0-6000 RPM range, accuracy F 40 RPM, and a resolution of 20 RPM. * Vacuum pump with 0-30 in. Hg range. * Timing light. * Spark tester. A modified spark plug with side electrode removed and alligator clip attached may be used.

* Fuel Injection Pressure Gauge (Part No. T80L-9974-A). * Non-powered, 12-volt test lamp. * Jumper wire, about 15" long. * MAP/BP Tester. Unit plugs into MAP/BP sensor circuit and DVOM to check input and output voltages to verify correct sensor operation.

NOTE: STAR diagnostic tester is available from Hikok Electrical Instrument Co., 10514 Dupont Ave., Cleveland, OH 44106.

READING SELF-TEST CODES

Service codes are transmitted to Pin No. 4 (Self-Test Output)of SELF-TEST connector in the form of timed pulses. All service codesare 2 digit numbers which are generated one digit at a time. Codes areshown as voltage pulses (needle sweeps) on an analog volt/ohmmeter(VOM). If a VOM is being used, careful attention to the length ofthe pauses is necessary in order to read the codes correctly. Therewill be a 2 second pause between each DIGIT in a code. There will be a4 second pause between each CODE. The continuous memory codes areseparated from the functional test service codes by a 6 second delay,a single 1/2 second sweep, and another 6 second delay. If a diagnostic tester is used, it will count the pulses anddisplay them as a digital code. The STAR tester will add a zero (0) tosingle digit (Separator and Dynamic Response) codes.

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Separator Pulse A single 1/2 second separator pulse is issued 6-9 secondsafter last functional KEY ON/ENGINE OFF (KOEO) SELF-TEST code. Then 6-9 seconds after the single 1/2 second separator pulse, the continuousmemory codes will be displayed.

Continuous Memory Codes These codes are issued as a result of information storedduring CONTINUOUS MONITOR (WIGGLE) TEST. These codes are displayedonly during KEY ON/ENGINE OFF (KOEO) SELF-TEST and after separatorcode. These codes should be used to diagnose ONLY when (KOEO) and KEYON/ENGINE RUNNING (KOER) SELF-TESTS result in code 11 and all QUICKTEST steps have been successfully completed.

QUICK TESTS

The QUICK TEST diagnostic procedure is a functional test ofthe EEC-IV system. It consists of 4 basic test steps. These basicsteps must be carefully followed in sequence, otherwise misdiagnosis,or replacement of non-faulty components may result. Perform QUICK TEST as follows: perform PREPARATION andEQUIPMENT HOOK-UP steps, KEY ON/ENGINE OFF (KOEO) SELF-TEST, TIMINGCHECK, KEY ON/ENGINE RUNNING (KOER) SELF-TEST, and CONTINUOUS SELF-TEST. After all tests, servicing, or repairs have been completed,repeat QUICK TEST to ensure EEC-IV system works properly.

* The KEY ON/ENGINE OFF (KOEO) SELF-TEST is a static check of the EEC-IV system inputs and outputs. The TIMING CHECK verifies the systems ability to compute and maintain a fixed spark timing during SELF-TEST. * The KEY ON/ENGINE RUNNING (KOER) SELF-TEST is a dynamic system check with the engine under actual operating conditions and at normal operating temperature. The CONTINUOUS SELF-TEST checks the sensor inputs for opens and shorts while the vehicle is in operation. * The KEY ON/ENGINE OFF and KEY ON/ENGINE RUNNING SELF-TESTS are intended to detect faults present at the time of testing, not intermittent faults. Intermittent faults are detected by CONTINUOUS SELF-TEST.

KEY ON/ENGINE OFF (KOEO) SELF-TEST

NOTE: Continuous memory codes recorded in this step will be used for diagnosis in CONTINUOUS SELF-TEST.

Code Output Correct test results for system are dependent on the correctoperation of several related non-EEC components and systems. It may benecessary to correct faults in these areas before EEC-IV will passQUICK TEST. Verify that vehicle has been properly prepared. SeePREPARATION and EQUIPMENT HOOK-UP. Turn ignition on to start SELF-TEST. DO NOT depress throttle during test. Observe and record allservice codes. 1) If engine does not start, go to CIRCUIT TEST A, step 1).If KEY ON/ENGINE OFF (KOEO) code and continuous memory indicate a pass(code 11), go to TIMING CHECK. 2) If any KOEO code is displayed with continuous memory code11, KOEO SELF-TEST indicates a fault. Record codes and go to TESTRESULTS & ACTION TO TAKE in this test. 3) If any (KOEO) or any continuous memory code is displayed,(KOEO) SELF-TEST and continuous memory indicate a fault. Record codes,

Page 5: 5.0L SEFI EEC IV TESTING - Carolina Broncos Forums - … - EFI - 5.0l eec iv testing.pdf · 5.0L SEFI EEC IV TESTING 1987 Lincoln Mark VII 1987 Computerized Engine Controls FORD MOTOR

but DO NOT repair continuous memory codes at this time. All (KOEO) andKEY ON/ENGINE RUNNING (KOER) SELF-TEST codes MUST be repaired first.Go to TEST RESULTS & ACTION TO TAKE in this test. 4) If (KOEO) code 11 displayed with ANY continuous memorycode (except 15), continuous memory indicates a fault. Record codes,but DO NOT repair continuous memory codes at this time. (KOEO) and(KOER) SELF-TEST codes MUST be repaired first. Go to TIMING CHECK. Ifengine idles rough, go to DIAGNOSIS BY SYMPTOM TEST. 5) If (KOEO) code 11 is displayed and continuous memory codeis 15, go to CIRCUIT TEST PP, step 9). If no codes are displayed,repeat SELF-TEST to verify that no service codes are present. If codesare not displayed, go to CIRCUIT TEST PP, step 1).

Test Results & Action To Take 1) Perform the test indicated in the KEY ON/ENGINE OFF (KOEO)SELF-TEST table for that specific engine. Start with the first codedisplayed. If the tests refer you to other checks, perform them asinstructed. 2) When more than one code is displayed, repair problems inthe order that codes are displayed. Whenever a repair is made, repeatQUICK TEST. If no codes are displayed, repeat SELF-TEST to verify thatno service codes are present, and then go to CIRCUIT TEST PP, step 1).

NOTE: See CIRCUIT TESTS at back of article.

CODE/TEST MENU (KOEO)

KEY ON/ENGINE OFF (KOEO) CIRCUIT TEST MENU�����������������������������������������������������������������������������������������

Code No. Go To: Circuit Test No. (Step No.)

15 ................................ PP (11)19 ................................ PP (14)21 .................................. G (1)22 .................................. H (1)23 .................................. J (1)24 .................................. E (1)31 .................................. M (1)32 ................................. M (13)34 ................................. M (12)35 .................................. M (5)51 .................................. G (4)

53 .................................. J (3)54 .................................. E (5)61 .................................. G (6)63 .................................. J (6)64 .................................. E (7)67 .................................. O (1)81 ................................. BB (8)82 ................................. BB (8)84 .................................. M (8)85 ................................. CC (6)87 .................................. Y (7)�����������������������������������������������������������������������������������������

TIMING CHECK

NOTE: If engine will not start, go to TEST A. If engine starts but stalls while testing, go to DIAGNOSIS BY SYMPTOM TEST.

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1) Turn ignition key off, and then wait 10 seconds. Verifythat SELF-TEST has been activated. Restart engine and check timingwhile in SELF-TEST mode. You are allowed 2 minutes to check timingfrom the time the last code is displayed. 2) Correct SELF-TEST timing equals base ignition timing (10

BTDC on all engines) plus 17-23�

BTDC. If timing is not 27-33�

BTDC,go to CIRCUIT TEST OO. If timing is 27-33

BTDC, go to KEY ON/ENGINERUNNING (KOER) SELF-TEST.

KEY ON/ENGINE RUNNING (KOER) SELF-TEST

NOTE: If engine will not start, go to TEST A. If engine starts but stalls while testing, go to DIAGNOSIS BY SYMPTOM TEST.

Code Output 1) Deactivate SELF-TEST (disconnect jumper wire). Startengine and run it at 2000 RPM for 2 minutes to warm up HEGO sensor.Turn engine off and wait 10 seconds 2) Start engine. Insert jumper to activate SELF-TEST. Theengine ID code will be displayed. 3) If a Dynamic Response code occurs, briefly accelerateengine to wide open throttle (WOT). DO NOT depress throttle duringtest unless a Dynamic Response code occurs. The KEY ON/ENGINE RUNNING(KOER) SELF-TEST service codes will then be displayed. Observe andrecord all codes.

NOTE: On the 5.0L SEFI engine a service code 98 may appear instead of the engine ID code, indicating the need to obtain a code 11 for the KEY ON/ENGINE OFF (KOEO) SELF-TEST portion of the QUICK TEST.

Test Results & Action To Take 1) If no codes are displayed, repeat SELF-TEST to verify thatno service codes are present, and then go to CIRCUIT TEST PP, step 1).If code 98 and any other code appears, go back and perform KEYON/ENGINE OFF (KOEO) SELF-TEST and obtain a code 11 for (KOEO) portionof QUICK TEST. 2) If Engine ID code is 2, 3 or 4 (20, 30 or 40 with STARtester), and code 11 is displayed, KEY ON/ENGINE RUNNING (KOER) SELF-TEST portion is okay. If symptom was of an intermittent nature, go toCONTINUOUS SELF-TEST. If symptom is present, go to DIAGNOSIS BYSYMPTOM TEST. 3) If Engine ID code is 2, 3 or 4 (20, 30 or 40 with STARtester), and any code other than 11 appears, (KOER) SELF-TEST portionis at fault. Perform the test indicated in the (KOER) SELF-TEST tablefor that specific engine. 4) Start with the first code displayed. If the tests referyou to other checks, perform them as instructed. When more than onecode is displayed, repair problems in the order that codes aredisplayed. Whenever a repair is made repeat QUICK TEST.

CODE/TEST MENU (KOER)

KEY ON/ENGINE RUNNING CIRCUIT TEST MENU�����������������������������������������������������������������������������������������

Code No. Go To: Circuit Test No. (Step No.)

12 ................................. DD (1)13 ................................ DD (11)16 ................................. DD (1)21 .................................. G (1)

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22 .................................. H (7)23 .................................. J (1)24 .................................. E (1)31 .................................. M (1)32 ................................. M (13)33 ................................. M (14)34 ................................. M (18)35 .................................. M (5)41 .................................. T (9)42 .................................. S (8)46 ................................. BB (1)91 .................................. U (9)92 ................................. T (15)94 ................................. BB (1)98 (1) .............................. .....99 (2) .............................. .....

(1) - If Code 98 is displayed, go back and perform KOEO SELF-TEST and obtain a Code 11 for KOEO part of QUICK-TEST.

(2) - Idle Speed Control (ISC) has not "learned" yet, repeat QUICK TEST.�����������������������������������������������������������������������������������������

CONTINUOUS SELF-TEST

NOTE: CONTINUOUS SELF-TEST is subdivided into 4 steps: CONTINUOUS MEMORY CODES, CLEARING CONTINUOUS MEMORY CODES, CONTINUOUS MEMORY CODES TO BE TESTED, and CONTINUOUS MONITOR (WIGGLE TEST). Perform steps in sequence.

Continuous Memory Codes 1) To ensure proper diagnosis of continuous memory codes,PREPARATION, EQUIPMENT HOOK-UP, KEY ON/ENGINE OFF (KOEO) SELF-TEST,TIMING CHECK, and KEY ON/ENGINE RUNNING (KOER) SELF-TEST must besuccessfully completed. If both (KOEO) and (KOER) SELF-TEST displaycode 11 (Pass), go to CLEARING CONTINUOUS MEMORY CODES. 2) If not, return to PREPARATION step and make the necessaryrepairs indicated in (KOEO) and (KOER) SELF-TEST before going toCLEARING CONTINUOUS MEMORY CODES.

Clearing Continuous Memory Codes Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST. When the firstservice code appears, exit SELF-TEST by disconnecting diagnostictester or by removing jumper wire from Self-Test Input (STI) pigtail.Exiting QUICK TEST in this manner will clear all codes stored incontinuous memory.

Continuous Memory Codes To Be Tested Check list of Continuous Memory codes that were recorded inKEY ON/ENGINE OFF (KOEO) and KEY ON/ENGINE RUNNING (KOER) SELF-TESTS.Disregard any codes that have already been repaired. To confirmremaining codes, go to CONTINUOUS MONITOR (WIGGLE) TEST.

Continuous Monitor (Wiggle) Test The Self-Test Output (STO) will be activated each time afault is detected. If the STO is activated long enough during thewiggle tests a service code will be stored. A fault is indicated by adeflection on VOM. The STAR tester LED will flash and/or sound analert signal when fault is recreated. The CONTINUOUS MONITOR (WIGGLE)TEST is used to attempt to recreate an intermittent fault.

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* KEY ON/ENGINE OFF (KOEO) Test: With SELF-TEST deactivated, turn ignition on to enter into wiggle test mode. Tap, move, and wiggle the suspected sensor and/or harness (in short sections). If a fault is detected, a service code will be stored in memory and will be indicated by VOM or diagnostic tester. Retrieve code and perform test indicated in CONTINUOUS SELF-TEST table. * KEY ON/ENGINE RUNNING (KOER) Test: Start engine. Activate SELF-TEST, wait 10 seconds, deactivate, and then reactivate SELF-TEST. DO NOT turn engine off. You are now in KOER wiggle test mode. Tap, move, and wiggle the suspected sensor and/or harness (in short sections). If a fault is detected, a service code will be stored in memory and will be indicated by VOM or diagnostic tester. Retrieve code and perform test indicated in CONTINUOUS SELF-TEST table.

NOTE: An alternate method of entering CONTINUOUS MONITOR (WIGGLE) TEST with engine running is to start KEY ON/ENGINE RUNNING (KOER) SELF-TEST, exit, and re-enter KOER SELF-TEST without turning off engine. If alternate method is being used, perform the following steps.

1) Observe VOM while moving, wiggling, and tapping systemharness (in short sections), connectors, and sensors. If anintermittent condition is created, the monitor will indicate this bystoring a service code. Carefully inspect harness and associatedconnectors of affected circuits. 2) If an intermittent condition is not created, carefullydisconnect sensor from harness. Remove terminals from connector andvisually inspect terminals at both ends for corrosion, bad crimps,improperly seated terminals, etc. 3) Reconnect harness after inspection. Disconnect ECA fromharness as carefully as possible. Remove and inspect terminalsassociated with sensor being checked. 4) If an intermittent condition cannot be created, plug-inconnector and erase the CONTINUOUS SELF-TEST service codes. To eraseservice codes, activate KEY ON/ENGINE OFF (KOEO) SELF-TEST. 5) Remove jumper wire from Self-Test Input (STI) terminal assoon as first code appears. Repeat SELF-TEST with jumper to verifythat service codes have been erased. QUICK TEST is complete.

CODE/TEST MENU (CONTINUOUS)

CONTINUOUS SELF-TEST CIRCUIT TEST MENU TABLE�����������������������������������������������������������������������������������������

Code No. Go To: Circuit Test No. (Step No.)

14 ................................. TT (1)15 ................................. PP (1)18 ................................. NN (1)22 ................................. H (15)31 ................................. M (25)32 ................................. M (23)33 ................................. M (27)

34 ................................. M (29)35 ................................. M (25)51 ................................. G (10)53 ................................. J (11)54 ................................. E (10)61 ................................. G (10)

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63 ................................. J (15)64 ................................. E (10)�����������������������������������������������������������������������������������������

QUICK TEST DIAGNOSTIC AIDS

Cylinder Balance Test The cylinder balance test is an aid in servicing the 5.0LSEFI fuel system by energizing and de-energizing each injectorseparately. This test mode is entered after all codes have beendisplayed. Immediately following the KEY ON/ENGINE RUNNING (KOER)SELF-TEST, lightly depress throttle (a 2-3 degree throttle angle isrequired, NOT a wide open throttle). Service codes displayed duringthis test correspond to cylinder number.

CYLINDER BALANCE TEST SERVICE CODES TABLE�����������������������������������������������������������������������������������������

Service Cylinder/ Breakout BoxCode Injector No. Test Pin No.

90 ............ Pass ............... Pass10 .............. 1 .................. 5820 .............. 2 .................. 5930 .............. 3 .................. 1240 .............. 4 .................. 1350 .............. 5 .................. 1460 .............. 6 .................. 1570 .............. 7 .................. 4280 .............. 8 .................. 5277 ............ Retest ........... Retest�����������������������������������������������������������������������������������������

If code 90 is displayed during this test it indicates a pass.If code 77 is displayed, repeat cylinder balance test. If throttle ismoved during this test, service code 77 will appear, indicating thattest was not completed. Total test time is about 90 seconds.

Dynamic Response Check The dynamic response check verifies movement of the TPS, andMAP sensor during the wide open throttle (WOT) part of the KEYON/ENGINE RUNNING (KOER) SELF-TEST. The signal to perform WOT is asingle pulse (one) when using VOM or code 10 on STAR tester.

Output State Check The Output State Check is used as an aid in servicing outputactuators associated with the EEC-IV system. It allows you to energizeand de-energize most of the system output actuators on and off oncommand. This mode is entered after all codes have been received fromKEY ON/ENGINE OFF (KOEO) and CONTINUOUS SELF-TEST. At this time, leaveSELF-TEST activated and depress throttle. Each time throttle isdepressed, the output actuators will change state (go from on to off,or off to on).

DIAGNOSIS BY SYMPTOM TEST

The DIAGNOSIS BY SYMPTOM TEST is divided into specific enginesections. Each section will describe testing procedures and codes forthat engine. Use appropriate DIAGNOSIS BY SYMPTOM TEST. The CIRCUITTESTS are common to all engines, unless noted in test procedures.

5.0L SEFI

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Use this test procedure ONLY when directed to do so byresults of QUICK TEST or steps in CIRCUIT TESTS. Follow test procedurecarefully. 1) When engine stalls in operation, misfires, lacks power,idles roughly, or has erratic RPM, perform the following checks:

* Check for, and repair, any bad ground or power connections. * Check ignition components (cap, rotor, wires, coil and plugs). * Check basic engine components (valves, cam timing, compression, etc.). * Perform SYSTEM CHECK, ISC Check, MAP Check, and EGR Check. Use CIRCUIT TEST QQ, steps 1), 2), and 3). * Perform CYLINDER BALANCE TEST. See QUICK TEST DIAGNOSTIC AIDS in this article.

2) If fuel pump is always on (noise coming from rear ofvehicle with key off), go to CIRCUIT TEST Y, step 12). 3) If shift indicator light is always on or off, go toCIRCUIT TEST FF, step 1). 4) If engine idle speed is low with A/C on, go to CIRCUITTEST O, step 9). 5) If A/C does not cut-off during wide open throttle (WOT),go to CIRCUIT TEST GG, step 1). 6) If detonation (engine knock) occurs due to improper EGRvalve function, check EGR and/or exhaust gas recirculation system. 7) If engine stalls during QUICK TEST due to faulty IdleSpeed Control (ISC) operation, go to CIRCUIT TEST DD, step 4). 8) If gasoline fumes accumulate in engine compartment, go toCIRCUIT TEST CC, step 1).

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Fig. 2: 5.0L SEFI EEC-IV Wiring Diagram (Continental & Mark VII)

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Fig. 3: 5.0L SEFI EEC-IV Wiring Diagram (Cougar & Thunderbird)

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Fig. 4: 5.0L SEFI EEC-IV Wir Diagram (Crown Victoria & Grand Marquis)

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Fig. 5: 5.0L SEFI EEC-IV Wiring Diagram (Mustang)

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Fig. 6: 5.0L SEFI EEC-IV Wiring Diagram (Town Car)

HOW TO USE CIRCUIT TESTS

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1) DO NOT perform any CIRCUIT TEST unless told to do so byQUICK TEST. Make sure all non-EEC related faults are corrected. Do notreplace any part unless directed to do so. When more than one servicecode is received, start with the first code displayed.

NOTE: Procedures in the TESTING section of this article are not in absolute numerical order. Procedures not related to this engine have been removed to eliminate confusion.

2) Do not measure voltage or resistance at ECA or connect anytest lamps to it, unless specified. All measurements are made byprobing REAR of connector. Isolate both ends of a circuit and turn keyoff whenever checking for shorts or continuity, unless specified. 3) Disconnect solenoids and switches from harness beforemeasuring continuity, resistance, or applying 12 volts. Follow eachtest step in order until fault is found. After each repair, check allcomponent connections and repeat CIRCUIT TEST(S). 4) An "open" is defined as any resistance reading higher than5 ohms, unless specified in CIRCUIT TEST. A "short" is defined as anyresistance reading less than 10,000 ohms to ground, unless specifiedin CIRCUIT TEST. 5) On FUEL CONTROL CIRCUIT TESTS S, T, U, V, W and X, toprevent replacement of good components, be aware that the followingnon-EEC related areas may also be at fault. These areas includeignition coil, distributor cap and rotor, spark plug wires, fouledspark plugs, CNAP problems, EGR valve and gasket, air filter, poorpower and ground circuits, fuel pressure, intake and exhaust manifoldleaks, engine not at normal operating temperature, and problems withPCV valves or fuel contaminated engine oil.

NOTE: Fuel contaminated engine oil may affect some service codes. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil and filter.

6) On FUEL CONTROL CIRCUIT TESTS S, T, U, V, W and X, vacuumleaks in non-EEC related areas may also cause code 41 or 91 to bedisplayed. Check for unmetered air between airflow meter and throttlebody, leaking vacuum motors, engine seals, EGR system, PCV system,canister purge (CANP) problems, or contaminated HEGO sensor. Code 42or 92 may be caused by fuel contaminated engine oil, ignition misfire,EGR system, or CANP problems.

NOTE: In the following diagnostic charts, circuits and illustrations are supplied courtesy of Ford Motor Co.

TEST A - NO START

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: fuel quantity andquality, ignition system damage, cracks, moisture, etc., enginemechanical conditions such as bad valves, timing belt, etc. Alsoincluded are starter and battery circuit problems. 1) Try to start engine. If engine does not crank, checkvehicle starting and charging systems. If engine cranks, but does notstart or else stalls after starting, go to next step. 2) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale and disconnect Throttle Position Sensor (TPS). Turn key on,leaving engine off. Measure voltage at TPS harness connector betweenvoltage reference (VREF) and signal return. If reading is less than 4.0 volts or more than 6.0 volts, go to CIRCUIT TEST C, step 1). Ifreading is between 4.0 and 6.0 volts, reconnect TPS and go to next

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step. 3) Disconnect any spark plug wire and connect spark testerbetween plug wire and engine ground. Crank engine and check for spark.If spark exists, connect spark plug wire and go to step 13). If thereis no spark, connect spark plug wire and go to next step. 4) Remove high tension coil wire from distributor and installspark tester. Check for spark while cranking engine. If spark exists,connect coil wire and service or repair TFI ignition system. If thereis no spark, connect coil wire and go to next step. 5) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Set DVOM on 200-ohm scale and disconnectTFI. Measure resistance between test pin No. 16 and TFI harnessconnector ignition ground. If reading is more than 5 ohms, repairharness and repeat QUICK TEST. If reading is less than 5 ohms, go tonext step. 6) With breakout box installed and box timing switch on"DISTRIBUTOR" position, connect TFI and ECA. Try to start vehicle. Ifvehicle starts, go to step 10). If vehicle does not start, go to nextstep. 7) Move breakout box timing switch to "COMPUTED" position.Set DVOM on 20-volt scale and measure voltage between test pin No. 36and chassis ground while cranking engine. If voltage is between 3.0and 6.0 volts, EEC system is NOT at fault. TFI ignition system shouldbe diagnosed. If voltage is less than 3.0 volts or more than 6.0volts, go to next step. 8) Turn key off and wait 10 seconds. With breakout boxinstalled, disconnect ECA and TFI. Set DVOM on 200,000-ohm scale andmeasure resistance between test pin No. 36 and test pins No. 16, 20,26, 40, and 60 for short to ground. Measure resistance between testpin No. 36 and test pins No. 37 and 57 for short to power. Measureresistance between test pins No. 36 and 56 for short to PIP. If anyreading is less than 10,000 ohms, repair short in harness and repeatQUICK TEST. If engine still does not start, go to next step. If allreadings are 10,000 ohms or higher, go to next step. 9) Turn key off and wait 10 seconds. With breakout boxinstalled, connect ECA, but leave TFI disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 36 and test pinsNo. 37 and 57 for short to power. Measure resistance between test pinNo. 36 and test pins No. 40 and 60 for short to ground. If any readingis less than 5 ohms, replace ECA and repeat QUICK TEST. If allreadings are 5 ohms or higher, connect TFI and go to next step. 10) With breakout box installed and DVOM on 20-volt scale,measure voltage between test pins No. 56 and 16, while crankingengine. If reading is between 3.0 and 6.0 volts, remove breakout box.Replace ECA and repeat QUICK TEST. If reading is less than 3.0 voltsor higher than 6.0 volts, go to next step. 11) Install breakout box, turn key off and wait 10 seconds.Set DVOM on 200-ohm scale. Disconnect TFI and ECA. Measure resistancebetween test pin No. 56 and TFI connector PIP circuit. If reading is 5ohms or more, repair open PIP circuit and repeat QUICK TEST. Ifreadings is less than 5 ohms, go to next step. 12) With breakout box installed and ECA disconnected, turnkey off. Disconnect TFI connector and set DVOM on 200,000-ohm scale.Measure resistance between test pin No. 56 and test pins No. 16, 20,26, 40, and 60 for short to ground. Measure resistance between testpin No. 56 and test pins No. 37 and 57 for short to power. Measureresistance between test pin No. 56 and test pin No. 36 for short toSpark Output (SPOUT). If any reading is less than 10,000 ohms, repairPIP circuit and repeat QUICK TEST. If all readings are higher than 10,000 ohms, diagnose TFI ignition system. 13) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector and inspect for damaged pins, corrosion, or loose wires.Repair as necessary. Install breakout box and connect ECA. Make sure

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that box timing switch is in "COMPUTED" position. Set DVOM on 20-voltscale and measure voltage between test pin No. 36 and chassis groundwhile cranking engine. If reading is between 3.0 and 6.0 volts, go tonext step. If reading is less than 3.0 volts or higher than 6.0 voltson all engines, go to step 10). 14) Fuel Pump Check Connect pressure gauge to vehicle. Noteinitial pressure reading, then pressurize fuel system by turning keyon for one second, turning key off, and then waiting 10 seconds.Repeat on, off, and wait sequence 5 times. Turn key off and wait 10seconds. If pressure increased, go to CIRCUIT TEST QQ, step 1). Ifpressure did not increase, go to next step. 15) Inertia Switch Check Turn key off. Install fuel pressuregauge. Locate fuel pump inertia switch and push button on switch toreset it to on. If switch will not reset to on, replace inertia switchand repeat step 14). If switch button was already on, go to CIRCUITTEST Y, step 1). Observe pressure gauge as system is pressurized as instep 14). If pressure reading increases, repeat QUICK TEST. Ifpressure reading does not increase, go to CIRCUIT TEST Y, step 1).

Fig. 7: TFI Module Circuits

TEST B - VEHICLE BATTERY

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: battery cables andground straps, voltage regulator, alternator, ignition switch. 1) Turn key on, leaving engine off. Set DVOM on 20-volt scaleand measure voltage across battery terminals. If reading is less than10.5 volts, service or replace discharged battery. If reading is 10.5volts or higher, go to next step. 2) Turn key off and wait 10 seconds. Install breakout box,but leave ECA connected. Set DVOM on 200-ohm scale and measureresistance between test pin No. 40 and negative post on battery. Alsomeasure resistance between test pin No. 60 and negative post onbattery. If readings are greater than 5 ohms, repair cause ofresistance in circuit(s). Repeat QUICK TEST. If both readings are less

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than 5 ohms, go to next step. 3) With breakout box installed and ECA connected, turn keyoff and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistancebetween test pins No. 40 and 46 and between test pins No. 46 and 60 atbreakout box. If both readings are less than 5 ohms, go to next step.If readings are greater than 5 ohms, disconnect ECA connector andinspect for corrosion or damaged pins. Repair if necessary. If faultis still present, replace ECA and repeat QUICK TEST. 4) With breakout box installed and ECA connected, turn keyoff and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistancebetween test pin No. 46 at breakout box and signal return circuit inSELF-TEST connector. If reading is greater than 5 ohms, repair causeof resistance in signal return circuit. Repeat QUICK TEST. If readingsis less than 5 ohms, go to next step. 5) Turn key on, leaving engine off. With ECA connected, setDVOM on 20-volt scale. Measure voltage between battery negative postand Keep Alive Power (KAPWR) circuit at EEC power relay. If reading isless than 10.5 volts, check KAPWR and vehicle power (V Power) circuitsfor shorts to ground. Also check KAPWR circuit from EEC power relay tobattery positive post for open circuit. If reading is 10.5 volts orhigher, go to next step. 6) Turn key on, leaving engine off. With ECA connected, setDVOM on 20-volt scale. Measure voltage between battery negative postand ignition circuit at EEC power relay. If readings is less than 10.5volts, check for open ignition switch circuits. Repair wiring andrepeat QUICK TEST. If reading is 10.5 volts or higher, go to nextstep. 7) Turn key off and wait 10 seconds. With ECA connected andDVOM on 200-ohm scale, measure resistance between battery negativepost and EEC relay ground. If reading is greater than 5 ohms, repairwiring in ground circuit. Repeat QUICK TEST. If reading is less than 5ohms, go to next step. 8) Turn key on, leaving engine off. With ECA connected andDVOM on 20-volt scale, measure voltage between battery negative postand VPWR circuit at EEC power relay. If reading is 10.5 volts orgreater, repair open in VPWR circuit. If okay, repair short to groundin VPWR circuit. If reading is less than 10.5 volts, replace EEC powerrelay. Repeat QUICK TEST. 9) Turn key on, leaving engine off. Connect VOM or diagnostictester to SELF-TEST connector. With SELF-TEST deactivated, enterCONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM or diagnostic tester forindication of fault while bending and twisting harness from EEC powerrelay to ECA. 10) If codes 72 or 78 are displayed or if fault is indicated,repair fault in vehicle power circuit. If codes 72 or 78 are notdisplayed or if fault is not indicated, inspect EEC power relay andconnectors for damaged pins, corrosion, etc. If okay, replace EECpower relay and repeat QUICK TEST.

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Fig. 8: Vehicle Battery Circuits

TEST C - REFERENCE VOLTAGE

1) Disconnect ECA 60-pin connector. Inspect connector fordamaged pins, corrosion, or loose wires. Repair if necessary. Installbreakout box, leaving ECA disconnected. Turn key on, leaving engineoff. Set DVOM on 20-volt scale and measure voltage between test pinNo. 37 and signal return in SELF-TEST connector. If reading is lessthan 10.5 volts, go to CIRCUIT TEST B, step 1). If reading is 10.5volts or higher, go to next step. 2) With breakout box installed and ECA connected, turn keyon, leaving engine off. Set DVOM on 20-volt scale and measure voltagebetween test pins No. 26 and 46. If reading is 6.0 volts or more, goto step 4). If reading is 4.0 volts or less, go to step 5). If readingis between 4.0 and 6.0 volts, go to next step. 3) With breakout box installed and ECA disconnected, turn keyoff. Set DVOM on 200-ohm scale. Measure resistance from test pins No.26 and 46 to suspect VREF sensor harness connector. If both readingsare less than 5 ohms, VREF voltage is okay. Connect all sensors andrepeat QUICK TEST. If any reading is 5 ohms or more, repair opencircuit in VREF or signal return and then repeat QUICK TEST.

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4) Turn key off and wait 10 seconds. With breakout boxinstalled and ECA disconnected, turn key on, leaving engine off. SetDVOM on 20-volt scale and measure voltage between test pin No. 26 andbattery ground. If reading is less than 0.5 volts, replace ECA andrepeat QUICK TEST. If reading is 0.5 volts or higher, repair short tobattery power in EEC harness. Repeat QUICK TEST. Replace ECA if faultstill occurs. 5) Shorted TPS Sensor. Turn key off and wait for 10 seconds.With breakout box installed and ECA connected, disconnect ThrottlePosition Sensor (TPS) from vehicle harness. Turn key on, leavingengine off. Set DVOM on 20-volt scale and measure voltage between testpins No. 26 and 46. If reading is 4.0 volts or more, replace TPS andrepeat QUICK TEST. If less than 4.0 volts on models with EVP sensor,go to step 6). If reading is less than 4.0 volts on all other models,go to next step. 6) Shorted EVP Sensor. Turn key off and wait 10 seconds. Withbreakout box installed and ECA connected, disconnect EVP sensor. Turnkey on, leaving engine off. Set DVOM on 20-volt scale. Measure voltagebetween test pins No. 26 and 46. If reading is 4.0 volts or more,replace EVP sensor and repeat QUICK TEST. If reading is less than 4.0volts, go to next step. 7) Shorted MAP/BP Sensor. Turn key off and wait 10 seconds.With breakout box installed and ECA connected, disconnect MAP/BPsensor. Turn key on, leaving engine off. Set DVOM on 20-volt scale.Measure voltage between test pins No. 26 and 46. If reading is 4.0volts or more, replace MAP/BP sensor and repeat QUICK TEST. If readingis less than 4.0 volts, go to next step. 8) With breakout box installed and ECA disconnected, turn keyoff and wait 10 seconds. Disconnect TPS, MAP and EVP sensor. Set DVOMon 200-ohm scale. Measure resistance between test pin No. 26 and testpins No. 20, 40, 46, and 60. If reading is less than 5 ohms, repairshort to ground, connect all sensors. Repeat QUICK TEST. If originalproblem still occurs, replace ECA. Repeat QUICK TEST. If reading is 5ohms or more, connect sensors, replace ECA and repeat QUICK TEST.

Fig. 9: Reference Voltage Circuits

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TEST D - VAT SENSOR

VANE AIR TEMPERATURE (VAT) SENSOR

Ambient air temperature must be at least 50�

F (10�

C) for testresults to be valid. Avoid performing test in unusually hot or coldconditions.

VANE AIR TEMP (VAT) SENS RESISTANCE TABLE�����������������������������������������������������������������������������������������

Ambient Ohms BetweenTemperature

F (�

C) Test Pin 25 (1) & 46

32 (0) ............................... 580065 (18) .............................. 2700185 (85) .............................. 300220 (104) ............................. 180240 (116) ............................. 125�����������������������������������������������������������������������������������������

1) Code 28 Displayed. Make sure ambient air temperature is atleast 50

F (10�

C). If not, repeat QUICK TEST. If temperature is highenough, go to next step. 2) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale. Disconnect Throttle Position Sensor (TPS). Turn key on, leavingengine off. Measure voltage at TPS connector between voltage reference(VREF) and signal return. If reading is less than 4.0 volts or morethan 6.0 volts, go to CIRCUIT TEST C, step 1). If reading is between4.0 and 6.0 volts, connect TPS and go to next step. 3) Turn key off and wait 10 seconds. Disconnect harness fromairflow meter. Set DVOM on 200,000-ohm scale. Measure resistance atVAT sensor between VAT signal and signal return. If reading is from125 ohms at 240

F (116�

C) to 3700 ohms at 50�

F (10�

C), replace ECA.Connect airflow meter and repeat QUICK TEST. If reading is out ofrange, replace airflow meter and repeat QUICK TEST. 4) Code 58 Displayed. Turn key off and wait 10 seconds.Disconnect harness from airflow meter. Inspect for and repair anydamaged wiring. Install a jumper wire between VAT signal and signalreturn at airflow meter connector. Perform KEY ON/ENGINE OFF SELF-TEST. If code 68 is displayed, replace airflow meter. Remove jumperwire, connect airflow meter, and repeat QUICK TEST. If code 68 is notdisplayed, remove jumper wire and go to next step. 5) Turn key off and wait 10 seconds. With jumper wireremoved, leave airflow meter disconnected. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measureresistance between test pin No. 25 and VAT signal at connector. Alsomeasure resistance between test pin No. 46 and signal return atconnector. If both readings are less than 5 ohms, replace ECA. Removebreakout box and connect wiring to ECA and airflow meter. Repeat QUICKTEST. If either reading is 5 ohms or more, repair open circuit. Removebreakout box, connect wiring to ECA and airflow meter, and then repeatQUICK TEST. 6) Code 68 Displayed. Turn key off and wait 10 seconds.Disconnect harness from airflow meter. Inspect for and repair anydamaged wiring. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST. If code 58is displayed, replace airflow meter and connect harness. Repeat QUICKTEST. If code 58 is not displayed, go to next step. 7) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale. Disconnect TPS. Turn key on, leaving engine off. Measurevoltage between VREF and signal return at connector. If reading isless than 4.0 volts or more than 6.0 volts, go to CIRCUIT TEST C, step

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1). If reading is between 4.0 and 6.0 volts, connect TPS and go tonext step. 8) Turn key off and wait 10 seconds. Leave airflow meterdisconnected. Disconnect ECA 60-pin connector. Inspect for and repairany damaged wiring. Install breakout box, leaving ECA disconnected.Set DVOM on 200,000-ohm scale. Measure resistance between test pin No.25 and test pins No. 40, 46, and 60. If any reading is less than 10,000 ohms, repair shorts. Remove breakout box, connect ECA and airflowmeter. Repeat QUICK TEST. If all readings are 10,000 ohms or more,replace ECA. Remove breakout box. Connect ECA. Repeat QUICK TEST. 9) Continuous Code 58 or 68 Displayed. Using CONTINUOUSMONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indicationof fault while tapping VAT sensor lightly and wiggling connector. Iffault is indicated, inspect connector and terminals. If connector andterminals are good, replace VAT sensor and repeat QUICK TEST. If nofault is indicated, go to next step. 10) While in CONTINUOUS MONITOR (WIGGLE) TEST, wiggle andbend EEC-IV harness from VAT sensor to firewall, a small section at atime. Also check harness from firewall to ECA. If fault is indicated,isolate fault and repair as necessary. Repeat QUICK TEST. If no faultis found, go to next step. 11) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connector and connector terminals for obviousdamage. If connectors and terminals are not okay, repair as necessaryand repeat QUICK TEST. If connectors and terminals are okay, and youare unable to duplicate fault at this time, continuous code 58 or 68testing is complete.

Fig. 10: VAT Sensor Circuit

TEST E - ACT SENSOR

AIR CHARGE TEMPERATURE (ACT) SENSOR

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: cooling system,improper engine oil level, air cleaner duct problem. Ambient airtemperature must be at least 50

F (10�

C) for test results to be valid.Avoid performing test in unusually hot or cold conditions.

AIR CHARGE TEMP (ACT) SENS RESISTANCE TABLE���������������������������������������������������������������������������������������������

Ambient Ohms Between

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Temperature �

F (�

C) Test Pin 25 & 46

50 (10) .............................. 58,75065 (18) .............................. 40,500180 (82) ............................... 3600220 (104) .............................. 1840���������������������������������������������������������������������������������������������

1) Code 24 Displayed. For vehicles with ACT sensor mounted inintake manifold, go to next step. If sensor is properly mounted in aircleaner on all other models, go to next step. If sensor is notproperly mounted, install ACT sensor properly and repeat QUICK TEST. 2) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale and disconnect Throttle Position Sensor (TPS). Turn key on,leaving engine off. Measure voltage between VREF and signal return atTPS connector. If reading is less than 4.0 volts or more than 6.0volts, go to CIRCUIT TEST C, step 1). If reading is between 4.0 and 6.0 volts, connect TPS and go to next step. 3) Start engine and make sure that engine reaches normaloperating temperature. Turn key off and wait 10 seconds. DisconnectACT sensor, set DVOM on 200,000-ohm scale, and measure ACT sensorresistance. If reading is less than 1100 ohms or more than 58,000ohms, check function of heat stove duct valve. If valve is operatingcorrectly, replace ACT sensor, connect ACT sensor, and repeat QUICKTEST. If reading is between 1100 and 58,000 ohms, go to next step. 4) Turn key off. Disconnect ACT sensor harness. Set DVOM on200,000-ohm scale and run engine for 2 minutes. While engine isrunning, measure ACT sensor resistance. If reading is between 2400 and29,000 ohms, replace ECA, connect ACT harness, and repeat QUICK TEST.If reading is less than 2400 ohms or more than 29,000 ohms, checkfunction of heat stove duct valve. If valve works properly, replaceACT sensor. Repeat QUICK TEST. 5) Code 54 Displayed. Turn key off and wait 10 seconds.Disconnect ACT sensor harness. Inspect for and repair any damagedwiring. Install a jumper wire between ACT signal and signal return atconnector. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST. If code 64 isdisplayed, replace ACT sensor. Remove jumper wire, connect ACT sensor,and repeat QUICK TEST. If code 64 is not displayed, remove jumper wireand go to next step. 6) Turn key off and wait 10 seconds. Leave ACT sensor harnessdisconnected. Disconnect ECA 60-pin connector. Inspect for and repairany damaged wiring. Install breakout box, leaving ECA disconnected.Set DVOM on 200-ohm scale. Measure resistance between test pin No. 25and ACT signal at ACT connector, and between test pin No. 46 andsignal return at ACT connector. If both readings are less than 5 ohms,replace ECA and remove breakout box. Connect ECA and ACT sensor, andthen repeat QUICK TEST. If either reading is 5 ohms or more, repairopens in circuit. Remove breakout box, and connect ECA and ACT sensor.Repeat QUICK TEST. 7) Code 64 Displayed. Turn key off and wait 10 seconds.Disconnect ACT sensor. Inspect for and repair any damaged wiring.Perform (KOEO) SELF-TEST. If code 54 is displayed, replace ACT sensor,connect harness, and repeat QUICK TEST. If code 54 is not displayed,go to next step. 8) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale and disconnect TPS. Turn key on, leaving engine off. Measurevoltage between VREF and signal return at TPS connector. If reading isless than 4.0 volts or more than 6.0 volts, go to CIRCUIT TEST C, step1). If reading is between 4.0 and 6.0 volts, connect TPS and go tonext step. 9) Turn key off and wait 10 seconds. Disconnect harness atACT sensor. Disconnect ECA 60-pin connector. Inspect for and repairany damaged wiring. Install breakout box and set DVOM on 200,000-ohm

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scale. Measure resistance between test pin No. 25 and test pins No.40, 46, and 60. If any reading is less than 10,000 ohms, repairshorts. Remove breakout box, and connect ECA and ACT sensor. RepeatQUICK TEST. If all readings are 10,000 ohms or more, replace ECA.Remove breakout box, and connect ECA and ACT sensor. Repeat QUICKTEST. 10) Continuous Code 54 or 64 Displayed. Using CONTINUOUSMONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indicationof fault while tapping ACT sensor lightly and wiggling connector. Iffault is indicated, inspect connector and terminals. If connector andterminals are good, replace ACT sensor and repeat QUICK TEST. If nofault is indicated, go to next step. 11) While in CONTINUOUS MONITOR (WIGGLE) TEST, wiggle andbend small sections of harness from ACT sensor to firewall. Repeataction from firewall to ECA. If fault is indicated, isolate fault andrepair as necessary. Repeat QUICK TEST. If no fault is indicated, goto next step. 12) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connector and connector terminals for obviousdamage. If connectors and terminals are not okay, repair as necessaryand repeat QUICK TEST. If connectors and terminals are okay, and youare unable to duplicate fault at this time, continuous code 54 or 64testing is complete.

Fig. 11: Air Charge Temperature (ACT) Sensor Circuit

TEST F - EVP/EGRC/EGRV

EGR VALVE POSITION (EVP) SENS, EGR CTRL (EGRC) SOLENOID & EGR VENT (EGRV) SOLENOID

To prevent replacement of good components, be aware that thefollowing non-EEC related area may be at fault: damaged EGR valve.

NOTE: The 5.0L SEFI does not use either an EGRC or an EGRV. When following these steps, ignore references to the EGRC and EGRV, but follow the procedures for the EVP.

1) Code 31 Displayed. Turn key off and wait 10 seconds.Disconnect and plug vacuum line at EGR valve. Perform KEY ON/ENGINERUNNING (KOER) SELF-TEST. If code 31 is not displayed but codes 32 and34 are, go to step 8). If code 31 is displayed, go to next step. 2) Turn key off and wait 10 seconds. Leave EGR vacuum linedisconnected and plugged. Disconnect EVP sensor harness. Set DVOM on200,000-ohm scale and connect vacuum pump to EGR valve. Measureresistance between EVP signal and VREF at EVP connector while vacuumis slowly increased to 10 in. Hg. If reading is less than 100 ohms ormore than 5500 ohms, replace EVP sensor, connect vacuum signal line

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and harness. Repeat QUICK TEST. If reading does not decrease or valvedoes not hold vacuum, go to step 14). If reading gradually decreasesfrom a maximum of 5500 ohms to a minimum of 100 ohms, go to next step. 3) Turn key on, leaving engine off. Disconnect and plugvacuum signal line and disconnect EVP sensor harness. Set DVOM on 20-volt scale. Measure voltage between VREF and signal return at EVPconnector. If reading is less than 4.0 volts or more than 6.0 volts,go to CIRCUIT TEST C, step 1). If reading is between 4.0 and 6.0volts, go to next step. 4) Turn key off and wait 10 seconds. Disconnect harness atEVP sensor and ECA 60-pin connector. Inspect for and repair anydamaged wiring. Install breakout box, leaving ECA disconnected. SetDVOM on 200-ohm scale. Measure resistance between test pin No. 27 andEVP signal at EVP connector. If reading is 5 ohms or more, repair openin circuit. Remove breakout box, connect ECA and EVP sensor, and thenrepeat QUICK TEST. If reading is less than 5 ohms, go to next step. 5) Turn key off and disconnect harness at EVP sensor. Installbreakout box, leaving ECA disconnected. Set DVOM on 200,000-ohm scale.Measure resistance between test pin No. 27 and test pins No. 26, 40,46, and 60. If any reading is less than 10,000 ohms, repair shortcircuit. Remove breakout box, connect ECA and EVP sensor, then repeatQUICK TEST. If all readings are 10,000 ohms or more, go to next step. 6) Turn key off and wait 10 seconds. Connect known good EVPsensor and EGR valve assembly to harness and vacuum lines. Removebreakout box and connect ECA. Perform KEY ON/ENGINE OFF SELF-TEST. Ifcode 31 is displayed, replace ECA. Connect original EVP sensor and EGRvalve assembly. Repeat QUICK TEST. If code 31 is not displayed, go tonext step. 7) Turn key off and wait 10 seconds. Install original EVPsensor to known good EGR valve. Connect EVP sensor. Perform KEYON/ENGINE OFF (KOEO) SELF-TEST. If code 31 is displayed, replace EVPsensor. Repeat QUICK TEST. If code 31 is not displayed, service EGRsystem. 8) Codes 32, 33, or 34 Displayed. Use DVOM for this step. Donot use diagnostic tester. Turn key off and wait 10 seconds. Set DVOMon 20-volt scale. Connect DVOM negative test lead to STO and positivelead to battery positive post. Connect jumper wire between STI andsignal return. Perform (KOEO) SELF-TEST until end of CONTINUOUS SELF-TEST codes (DVOM reads 0 volts). Depress and release throttle. Ifreading does not change to high voltage, depress throttle to WOT andrelease. If STO voltage does not go high, go to CIRCUIT TEST PP, step12). If DVOM reading does go high, stay in OUTPUT STATE CHECK and goto next step. 9) Turn key on, leaving engine off. Stay in OUTPUT STATECHECK. Set DVOM to 20-volt scale. Connect DVOM between EGRV solenoid,VPWR and EGRV signal. Depress and release throttle several times tocycle output on and off while observing DVOM. Repeat check for EGRCsolenoid, VPWR and EGRC signal. If either solenoid does not cycle onand off, exit OUTPUT STATE CHECK and go to step 15). If both solenoidscycle on and off, stay in OUTPUT STATE CHECK and go to next step. 10) Turn key on, leaving engine off. Stay in OUTPUT STATECHECK. Disconnect and plug vacuum line from bottom port of EGRCsolenoid. Connect vacuum pump to open port. Connect vacuum gauge incommon output (upper) vacuum line to EGR valve. Disconnect, but DO NOTplug vacuum vent line from EGRV solenoid. Maintain source vacuum andcycle output on and off by depressing and releasing throttle. 11) If vacuum does not cycle on and off in less than 2seconds, check solenoid filter for obstructions, and replace ifnecessary. If filter is okay, replace solenoid assembly. Afterrepairs, connect all vacuum lines and repeat QUICK TEST. If vacuumoutput cycles on and off in less than 2 seconds, connect all vacuumlines and go to next step. 12) Turn key off and wait 10 seconds. Connect all vacuum

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lines, and check vacuum lines for proper routing, kinks, cracks,obstructions, leaks, etc. Use vehicle emissions decal as a guide. Ifvacuum lines are not okay, repair as necessary and repeat QUICK TEST.If vacuum lines are okay, go to next step. 13) With key off, disconnect EVP sensor harness. Inspect forand repair any damaged wiring. Set DVOM on 200,000-ohm scale.Disconnect vacuum line at EGR valve and connect vacuum pump to valve.Measure resistance of EVP sensor between EVP signal and VREF terminalswhile increasing vacuum to 10 in. Hg. If reading slowly decreases frommaximum of 5500 ohms to minimum of 100 ohms, replace ECA. Connect EVPsensor and EGR vacuum line. Repeat QUICK TEST. If reading does notslowly decrease, go to next step. 14) With key off, disconnect EVP sensor harness. Remove EVPsensor and vacuum line from EGR valve. Measure resistance of EVPsensor between EVP signal and VREF terminals. Observe resistancechanges as EVP sensor shaft is slowly pushed in and slowly released.If both readings increase and decrease smoothly in range of 100-5500ohms, replace EGR valve assembly. Connect EVP sensor and EGR vacuumline. Repeat QUICK TEST. If either reading changes abruptly duringrange of 100-5500 ohms, replace EVP sensor. Reconnect harness and EGRvacuum line. Repeat QUICK TEST.

NOTE: It is normal for EVP sensor total resistance to drop below 100 ohms when disconnected from EGR valve. A defective sensor will change resistance suddenly between 5500 and 100 ohms.

15) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Disconnect EGRC and EGRV solenoids from harness. Inspect forand repair any damaged wiring. Measure resistance of both solenoids.If either reading is less than 30 ohms or more than 70 ohms, replaceEGRC/EGRV solenoid assembly. Repeat QUICK TEST. If both readings arebetween 30 and 70 ohms, reconnect solenoids and go to next step. 16) Disconnect EGRC and EGRV solenoids from harness. Turn keyon, leaving engine off. Set DVOM on 20-volt scale. Measure voltagebetween battery negative terminal and VPWR circuit for both solenoids.If either reading is less than 10.5 volts, repair open circuit andrepeat QUICK TEST. If both readings are 10.5 volts or more, go to nextstep. 17) Turn key off and wait 10 seconds. Leave EGRC and EGRVsolenoids disconnected. Disconnect ECA 60-pin connector. Inspect forand repair any damaged wiring. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 33 and EGRV signal at EGRV solenoid connector. Measureresistance between test pin No. 52 and EGRC signal at EGRC solenoidconnector. If either reading is 5 ohms or more, repair open circuit.Remove breakout box, connect ECA and solenoids, then repeat QUICKTEST. If both readings are less than 5 ohms, go to next step. 18) Turn key off and wait 10 seconds. Set DVOM on 200,000-ohmscale. Install breakout box, leaving ECA disconnected. Disconnect EGRCand EGRV solenoids. Measure resistance between test pin No. 33 and/or52 and test pins No. 40, 46, and 60. If readings are less than 10,000ohms, repair short to ground. Repeat QUICK TEST. If readings are 10,000 ohms or more, go to next step. 19) With key off, disconnect EGRC and EGRV solenoids fromharness. Install breakout box, leaving ECA disconnected. Set DVOM on200,000-ohm scale. Measure resistance between test pin No. 33 and testpins No. 37 and 57. Measure resistance between test pin No. 52 andtest pins No. 37 and 57. If any reading is less than 10,000 ohms,repair short in circuit. Remove breakout box and connect ECA. RepeatQUICK TEST. If code is repeated, replace ECA. If all readings are 10,000 ohms or more, replace ECA. Remove breakout box and connect ECA.Repeat QUICK TEST.

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20) Code 35 Displayed. This code indicates that engine RPM istoo low for correct EGR testing. If code 12 is also displayed, go to:

* CIRCUIT TEST DD, step 1) for EFI models with air by-pass. * CIRCUIT TEST EE, step 1) for models with an idle speed control motor.

If code 12 is not displayed with code 35, go to next step.

21) Turn key off and wait 10 seconds. Install tachometer.Perform (KOER) SELF-TEST at 1500 RPM. Record (KOER) service codes. Ifcode 35 is displayed, replace ECA and repeat QUICK TEST. If code 35 isnot displayed, repeat QUICK TEST and repair codes as necessary. 22) Continuous Code 31 Displayed. Using CONTINUOUS MONITOR(WIGGLE) TEST, observe VOM or diagnostic tester for indication offault while doing the following: connect vacuum pump to EGR valve.Very slowly apply 6 in. Hg vacuum to EGR valve. Bleed vacuum slowlyand lightly tap on EVP sensor. Wiggle EVP sensor connector. If faultis indicated, go to next step. If no fault is indicated, go to step24). 23) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox and connect ECA. Stay in CONTINUOUS MONITOR (WIGGLE) TEST. ConnectDVOM between test pins No. 27 and 46. Set DVOM on 20-volt scale. Turnkey on, leaving engine off. Repeat step 22) while watching voltage. Iffault occurs below 4.25 volts, disconnect EVP sensor from harness.Inspect for and repair any damaged wiring. If wiring is good, replaceEVP sensor. Repeat QUICK TEST. If fault does not occur below 4.25volts, EGR valve overshoot may have caused continuous code 31. Sensortest is complete. Go to next step for harness test. 24) While in CONTINUOUS MONITOR (WIGGLE) TEST, bend, shake,and wiggle small sections of EEC-IV harness from sensor to firewalland from firewall to ECA. If fault is indicated, isolate fault andrepair as necessary. Repeat QUICK TEST. If no fault is indicated, goto next step. 25) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connector and terminals for obvious damage. Ifconnector and terminals are damaged, repair as necessary, then repeatQUICK TEST. If connector and terminals are okay, fault cannot beduplicated at this time. Continuous code 31 testing is complete.

Fig. 12: EVP, EGRC & EGRV Solenoid Circuits

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TEST G - ECT SENSOR

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

NOTE: For purposes of this test, a "warmed up" engine has a coolant temperature of 50-240

F (10-116�

C) for KEY ON/ENGINE OFF (KOEO) SELF-TEST and 180-240

F (82-116�

C) for KEY ON/ENGINE RUNNING (KOER) SELF-TEST. The test procedure will be invalid outside these ranges.

COOLANT TEMP (ECT) SENS RESISTANCE TABLE�����������������������������������������������������������������������������������������

Ambient Ohms BetweenTemperature

F (�

C) Test Pins No. 7 & 46

50 (10) ............................ 58,75065 (18) ............................ 40,500180 (82) ............................. 3600220 (104) ............................ 1840�����������������������������������������������������������������������������������������

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: coolant or oil level,blocked or obstructed air flow, engine not at normal operatingtemperature, or cooling fan.

1) Code 21 Displayed. Start engine and run it at 2000 RPM for2 minutes. Check that upper radiator hose is hot and pressurized.Repeat QUICK TEST before continuing. If vehicle stalls, DO NOT servicecode 21 at this time, go directly to DIAGNOSIS BY SYMPTOM TEST. Ifcode 21 is not displayed, service other codes as necessary (ifdisplayed). If code 21 appears, go to next step. 2) Turn key off and wait 10 seconds. Disconnect TPS. Set DVOMon 20-volt scale. Turn key on, leaving engine off. Measure voltage atTPS harness connector between VREF and signal return. If voltage isless than 4.0 volts or more than 6.0 volts, go to CIRCUIT TEST C, step1). If voltage is between 4 and 6 volts, reconnect TPS and go to nextstep. 3) Make sure engine is fully warmed up for this step. Turnkey off and wait 10 seconds. Disconnect wiring harness at ECT sensor.Set DVOM on 200,000-ohm scale and measure resistance of ECT sensor. Ifreading is 1300-7700 ohms at engine coolant temperature of 240-140

F(116-60

C) with engine off and 1550-4550 ohms at 230-180�

F (110-82�

C)with engine running, replace ECA, connect ECT sensor, then repeatQUICK TEST. If readings are not correct for coolant temperature,replace ECT sensor, connect harness, and repeat QUICK TEST. 4) Code 51 Displayed. Turn key off and wait 10 seconds.Disconnect ECT sensor at wiring harness and inspect wiring for damageor corrosion. Connect a jumper wire between ECT signal and signalreturn terminals in sensor harness connector. Repeat KEY ON/ENGINE OFF(KOEO) SELF-TEST. If code 61 is displayed, replace ECT sensor andremove jumper wire. Reconnect harness to ECT sensor and repeat QUICKTEST. If code 61 is not displayed, go to next step. 5) Turn key off and wait 10 seconds. With harnessdisconnected at ECT sensor and jumper removed from harness connector,disconnect ECA 60-pin connector. Inspect for and repair any damagedwiring. Install breakout box, leaving ECA disconnected. Set DVOM on200-ohm scale. Measure resistance between ECT signal at ECT connectorand test pin No. 7. Measure resistance between signal return at ECTconnector and test pin No. 46. If both readings are less than 5 ohms,replace ECA. Remove breakout box and connect ECA and ECT sensor.Repeat QUICK TEST. If either reading is 5 ohms or more, repair open

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circuits. Remove breakout box, and connect ECA and ECT sensor. RepeatQUICK TEST. 6) Code 61 Displayed. Turn key off and wait 10 seconds.Disconnect ECT sensor and inspect connector for damage or corrosion.Repair wiring and repeat KOEO SELF-TEST. If code 51 is displayed,replace ECT sensor, connect sensor, then repeat QUICK TEST. If code 51is not displayed, go to next step. 7) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale. Disconnect TPS. Turn key on, leaving engine off. Measurevoltage between VREF and signal return at TPS connector. If reading isless than 4.0 volts or more than 6.0 volts, go to CIRCUIT TEST C, step1). If voltage is between 4.0 and 6.0 volts, connect TPS and go tonext step. 8) Turn key off and wait 10 seconds. Disconnect harness fromECT sensor. Disconnect ECA 60-pin connector. Inspect for and repairany damaged wiring. Install breakout box, leaving ECA disconnected.Set DVOM on 200,000-ohm scale. Measure resistance between test pin No.7 and test pins No. 40, 46, and 60. If any reading is less than 10,000ohms, repair short circuits. Remove breakout box, connect ECA and ECTsensor, then repeat QUICK TEST. If all readings are 10,000 ohms ormore, replace ECA. Remove breakout box, connect ECA and ECT sensor.Repeat QUICK TEST. 9) Continuous Code 21 Displayed. Turn key off and wait 10seconds. Disconnect all SELF-TEST equipment. Prepare vehicle for testdrive. While driving vehicle, attempt to copy driving style in whichcomplaint was noticed. If problem occurs, try to maintain conditionfor one or more minutes. After road test, repeat KOEO SELF-TEST. Ifcode 21 is present in CONTINUOUS SELF-TEST, make sure that thermostatis working properly. If thermostat functions properly, replace ECTsensor. Repeat QUICK TEST. If code 21 is not displayed, fault cannotbe duplicated at this time. Continuous code 21 testing is complete. 10) Continuous Code 51 or 61 Displayed. Using CONTINUOUSMONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indicationof fault while tapping ECT sensor and wiggling ECT connector. If faultis indicated, disconnect and inspect ECT connector and terminals. Ifconnector and terminals are okay, replace ECT sensor and repeat QUICKTEST. If no fault is indicated, go to next step. 11) While in CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM ordiagnostic tester for indication of fault as you bend, shake or wiggleEEC-IV harness. Start at sensor connector and work toward firewall.Also test harness from firewall to ECA in same manner. If fault isindicated, isolate fault in wiring and repair as necessary. RepeatQUICK TEST. If fault is not indicated, go to next step. 12) Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for obvious damage.If connectors and terminals are damaged, repair as necessary andrepeat QUICK TEST. If connectors and terminals are okay, fault cannotbe duplicated at this time. Continuous code 51 or 61 testing iscomplete.

Fig. 13: Engine Coolant Temperature (ECT) Sensor Circuit

TEST H - MAP SENSOR

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MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

NOTE: Barometric pressure sensor output is digital and must be measured with MAP/BP tester.

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: unusually high/lowatmospheric barometer reading, kinked or blocked vacuum lines, enginecondition (valves, vacuum leaks, valve timing, EGR valve, etc.). 1) Code 22 Displayed, Engine Off. Turn key off. DisconnectMAP sensor from harness. Connect MAP/BP tester between wiring harnessand MAP sensor. Connect banana plugs of tester into DVOM and set DVOMon 20-volt scale. See MAP/BP Tester Hook-Up. Go to next step.

Fig. 14: MAP/BP Tester Hook-Up

2) With MAP/BP tester connected, turn key on. If only Greenlight on tester is lit, VREF is correct. Go to step 4). If "LESS THAN4 VOLTS" Red light or no lights come on, VREF is too low. If "MORETHAN 6 VOLTS" Red light comes on, VREF is too high. If VREF is toohigh or too low, go to next step. 3) With MAP/BP tester connected, turn key on. Disconnect MAPsensor and repeat step 2). If only Green light comes on, VREF iscorrect. Replace MAP sensor. Repeat QUICK TEST. If "LESS THAN 4 VOLTS"Red light or no lights come on, VREF is too low. If "MORE THAN 6VOLTS" Red light comes on, VREF is too high. If VREF is too high ortoo low, remove MAP/BP tester, connect sensor, then go to CIRCUIT TESTC, step 1). 4) With MAP/BP tester connected and key on, measure sensoroutput voltage. If voltage output is in correct range for altitude ofvehicle being tested, remove MAP/BP tester and go to next step. Ifoutput reading is outside range, remove MAP/BP tester and go to step6).

NOTE: Measure several known good MAP sensors on available vehicles. Mean voltage reading will be typical for your location on date of testing.

MAP VOLTAGE OUTPUT SPECIFICATIONS TABLE�����������������������������������������������������������������������������������������

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Elevation (Ft.) Voltage Output (Volts)

0 ............................ 1.55-1.631000 ............................ 1.52-1.602000 ............................ 1.49-1.573000 ............................ 1.46-1.544000 ............................ 1.43-1.515000 ............................ 1.40-1.486000 ............................ 1.37-1.457000 ............................ 1.35-1.43�����������������������������������������������������������������������������������������

5) Turn key off and wait 10 seconds. Disconnect MAP sensorfrom harness. Disconnect ECA 60-pin connector. Inspect for and repairany damaged wiring. Install breakout box, leaving ECA disconnected.Set DVOM on 200-ohm scale. Measure resistance between MAP signal atsensor connector and test pin No. 45. If reading is less than 5 ohms,replace ECA. Connect ECA and MAP sensor and repeat QUICK TEST. Ifreading is 5 ohms or higher, repair opens in wiring. Remove breakoutbox, connect ECA and MAP sensor. Repeat QUICK TEST. 6) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox, leaving ECA disconnected. Disconnect harness at MAP sensor. SetDVOM on 200,000-ohm scale. Measure resistance between test pin No. 45and test pins No. 26, 46, 40, and 60. If any reading is less than 10,000 ohms, repair shorts in wiring. Remove breakout box and connect ECAand MAP sensor. Repeat QUICK TEST. If all readings are 10,000 ohms ormore, replace MAP sensor. Remove breakout box and connect all wiring.Repeat QUICK TEST. 7) Code 22 Displayed, KEY ON/ENGINE RUNNING (KOER) . Check tosee if service codes 31, 32, 33, 34 or 35 are present. If so, go toKOER SELF-TEST table and perform appropriate CIRCUIT TEST. If not, goto next step. 8) Turn key off and wait 10 seconds. Disconnect vacuum hosefrom MAP sensor. Connect vacuum pump to MAP sensor and apply 18 in.Hg. vacuum to sensor. If sensor does not hold vacuum, replace sensor,connect vacuum line and repeat QUICK TEST. If MAP sensor does holdvacuum, release vacuum and go to next step. 9) Turn key off and wait 10 seconds. Plug vacuum hose goingto MAP sensor. Start engine and run at 1400-1700 RPM. Slowly apply 15in. Hg. vacuum to MAP sensor. With engine under these operatingconditions, perform KOER SELF-TEST. If code 22 is still present,replace MAP sensor. If code 22 is no longer displayed, inspect vacuumhose going to MAP sensor. If okay, service other codes. If there arenone, check engine for cause of low vacuum. 10) Code 72 Displayed. Turn key off and wait 10 seconds.Install vacuum gauge with "T" in manifold vacuum line at MAP sensor.Perform KOER SELF-TEST and observe vacuum reading before and duringDYNAMIC RESPONSE CHECK portion of test. Record service codes. Ifvacuum decreased 10 in. Hg or more and code 72 is not displayed,disconnect vacuum gauge and service other codes as necessary. Ifvacuum decreased 10 in. Hg and code 72 is displayed, replace MAPsensor and repeat QUICK TEST. If vacuum decreased less than 10 in. Hg,go to next step. 11) Check vacuum lines for correct routing, using vehicleemissions decal as a guide. Also check MAP sensor vacuum lines forkinks or blockage. If lines are good, EEC-IV system is okay. Checkengine for cause of low vacuum. If vacuum lines are bad, repair asnecessary and repeat step 9). 12) Turn key off. Disconnect MAP sensor from harness. ConnectMAP/BP tester between wiring harness and MAP sensor. Connect bananaplugs of tester into DVOM and set DVOM on 20-volt scale. See MAP/BPTester Hook-Up. Go to next step.

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13) Turn key on and measure sensor output. Compare values toMAP VOLTAGE OUTPUT table. If reading is within range, go to next step.If reading is out of range, replace MAP sensor. Repeat QUICK TEST. 14) Check map sensor vacuum lines for leaks, bad connections,kinks or blockage. If vacuum lines are okay, go to DIAGNOSIS BYSYMPTOM TEST. If vacuum lines are bad, repair as necessary and repeatQUICK TEST. 15) Continuous Code 22 Displayed. Using CONTINUOUS MONITOR(WIGGLE) TEST, observe VOM or diagnostic tester for indication offault while doing the following: connect vacuum pump to MAP sensor andslowly apply 25 in. Hg. Bleed vacuum slowly, tap MAP sensor lightly,and wiggle MAP connector. If fault is indicated, disconnect sensor.Inspect connector and terminals for damage. If connector and terminalsare okay, replace MAP sensor and repeat QUICK TEST. If no fault isindicated, go to next step. 16) Stay in CONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM ordiagnostic tester for indication of fault while shaking, bending orwiggling small sections of harness from sensor connector to firewall.Check harness from firewall to ECA in same manner. If fault isindicated, isolate fault in harness and repair as necessary. RepeatQUICK TEST. If no fault is indicated, go to next step. 17) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connectors and terminals for obvious damage.If connectors and terminals are not okay, repair as necessary. RepeatQUICK TEST. If connectors and terminals are okay, fault cannot beduplicated at this time. Continuous code 22 testing is complete.

Fig. 15: MAP Sensor Circuit

TEST J - TPS

THROTTLE POSITION SENSOR (TPS)

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: idle speed/throttlestop adjustment, binding throttle shaft/linkage or cruise controllinkage, or choke/high cam system (if equipped). 1) Code 23 Displayed. If KEY ON/ENGINE OFF (KOEO) SELF-TESTcode 68 or KEY ON/ENGINE RUNNING (KOER) SELF-TEST codes 31, 41, or 58are displayed, service these codes first. Disregard code 23 at thistime. If these codes have been serviced or are not displayed, go tonext step. 2) Inspect throttle body and linkage for mechanical bindingor sticking. Make sure linkage is set with throttle in closedposition. If throttle plate or linkage is binding, check for bindingthrottle or cruise control linkage, vacuum line or harnessinterference, etc. Repair problem(S) and repeat QUICK TEST. If nomechanical problem is found, go to next step. 3) Turn key off and wait 10 seconds. Disconnect TPS fromharness at throttle body. Inspect for and repair any damaged wiring.Perform KOEO SELF-TEST. Check for code 63. Ignore all other codes at

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this time. If code 63 is not displayed, go to step 5). If code 63 isdisplayed, go to next step. 4) Turn key off and wait 10 seconds. Set DVOM on 20-voltscale and disconnect TPS from harness. Inspect for and repair anydamaged wiring. Turn key on, leaving engine off. Measure voltage atTPS connector between VREF and signal return. If reading is less than4 volts or more than 6 volts, go to CIRCUIT TEST C, step 1). Ifreading is between 4 and 6 volts, replace TPS and repeat QUICK TEST. 5) Turn key off and wait 10 seconds. Disconnect TPS fromharness. Set DVOM on 200,000-ohm scale. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox, leaving ECA disconnected. Measure resistance between test pin No.47 and test pins No. 26 and 57. If either reading is less than 10,000ohms, repair short in harness and repeat QUICK TEST. If both readingsare 10,000 ohms or more, replace ECA and repeat QUICK TEST. 6) Code 63 Displayed. Turn key off and wait 10 seconds.Disconnect TPS from harness. Install a jumper wire between VREF andTPS signal at connector. Perform KOEO SELF-TEST. Check for codes 53 or23. Ignore all other codes at this time. If no codes are displayed,immediately remove jumper wire, and go to step 9). If either code 53or 23 are displayed, replace TPS and repeat QUICK TEST. If neithercode 53 or 23 are displayed, go to next step. 7) Turn key off and wait 10 seconds. Disconnect TPS fromharness. Inspect for and repair any damaged wiring. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage betweenVREF and signal return at TPS connector. If reading is less than 4volts or more than 6 volts, go to CIRCUIT TEST C, step 1). If readingis between 4 and 6 volts, go to next step. 8) Turn key off and wait 10 seconds. Leave TPS disconnected.Set DVOM on 200-ohm scale and disconnect ECA 60-pin connector. Inspectfor and repair any damaged wiring. Install breakout box and connectECA. Measure resistance between TPS signal at connector and test pinNo. 47. If reading is 5 ohms or more, repair faulty circuit. Removebreakout box, connect ECA and TPS, and then repeat QUICK TEST. Ifreading is less than 5 ohms, go to next step. 9) Turn key off and wait 10 seconds. Leave TPS disconnected.Disconnect ECA 60-pin connector. Inspect for and repair any damagedwiring. Install breakout box and set DVOM on 200,000-ohm scale.Measure resistance at connector between TPS signal and ground, andbetween TPS signal and test pin No. 46. If either reading is less than10,000 ohms, repair short circuit and repeat QUICK TEST. If bothreadings are 10,000 ohms or more, replace ECA. Remove breakout box,connect TPS, and then repeat QUICK TEST.

NOTE: Code 73 in step 10) indicates that TPS did not exceed 25% of its rotation during DYNAMIC RESPONSE CHECK. For additional information see QUICK TEST DIAGNOSTIC AIDS, DYNAMIC RESPONSE CHECK in front of this article.

10) Code 73 Displayed. Turn key off. Install breakout box andset DVOM on 20-volt scale. Connect DVOM to test pins No. 46 and 47.Perform KOER SELF-TEST. Verify that DVOM reading exceeds 3.5 voltsduring WOT of DYNAMIC RESPONSE CHECK. If reading exceeds 3.5 volts,replace ECA and repeat QUICK TEST. If reading does not exceed 3.5volts, make sure that TPS is correctly installed and adjusted. Ifokay, replace TPS and repeat QUICK TEST. 11) Continuous Code 53 Displayed. Using CONTINUOUS MONITOR(WIGGLE) TEST, observe VOM or diagnostic tester for indication offault while slowly opening throttle to WOT. Slowly bring throttle toclosed position, lightly tap TPS and wiggle connector. If no fault isindicated, go to step 13). If fault is indicated, go to next step. 12) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakout

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box, leaving ECA connected. Stay in CONTINUOUS MONITOR (WIGGLE) TESTand connect DVOM between test pin No. 47 and 46. Set DVOM on 20-voltscale. Turn key on, leaving engine off. Observe DVOM and repeat step11). If fault occurs below 4.25 volts, inspect TPS connectors andterminals. If okay, replace TPS and repeat QUICK TEST. If fault doesnot occur below 4.25 volts, TPS over-travel may have caused continuouscode 53. TPS is good, go to next step to check harness. 13) While in CONTINUOUS MONITOR (WIGGLE) TEST, shake, bendand wiggle small sections of EEC-IV harness from TPS sensor tofirewall, and from firewall to ECA. If fault is indicated, isolatefault in wiring and repair as necessary. Repeat QUICK TEST. If nofault is indicated, go to next step. 14) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connectors and terminals for obvious damage.If connectors and terminals are damaged, repair as necessary. RepeatQUICK TEST. If connectors and terminals are okay, fault cannot beduplicated at this time. Continuous code 53 testing is complete. 15) Continuous Code 63 Displayed. Using CONTINUOUS MONITOR(WIGGLE) TEST, observe VOM or diagnostic tester for indication offault while slowly opening throttle to WOT. Slowly bring throttle toclosed position and lightly tap TPS and wiggle connector. If fault isindicated, disconnect TPS. Inspect connectors and terminals. Ifconnectors and terminals are okay, replace TPS and repeat QUICK TEST.If no fault is indicated, go to next step. 16) While in CONTINUOUS MONITOR (WIGGLE) TEST, shake, bendand wiggle small sections of EEC-IV harness from TPS sensor tofirewall, and from firewall to ECA. If fault is indicated, isolatefault in wiring and repair as necessary. Repeat QUICK TEST. If nofault is indicated, go to next step. 17) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect both connectors and terminals for obvious damage.If connectors and terminals are damaged, repair as necessary. RepeatQUICK TEST. If connectors and terminals are okay, fault cannot beduplicated at this time. Continuous code 63 testing is complete.

Fig. 16: Throttle Position Sensor (TPS) Circuit

TEST M - EVP & EVR

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EGR VALVE POSITION (EVP) & EGR VALVE REGULATOR (EVR)

1) Code 31 Displayed. Turn key off. Disconnect EVP harness atsensor. Install a jumper wire between VREF and EVP signal at sensorharness connector. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST. Checkfor code 35. Ignore all other codes at this time. If code 35 isdisplayed, replace EVP sensor. Repeat QUICK TEST. If code 35 is notdisplayed, remove jumper wire and go to next step. 2) With key off and EVP disconnected, set DVOM on 20-voltscale. Turn key on, leaving engine off. Measure voltage at EVPconnector between VREF and signal return. If reading is less than 4.0or more than 6.0 volts, go to CIRCUIT TEST C, step 1). If reading isbetween 4.0 and 6.0 volts, go to next step. 3) With key off, and EVP disconnected, set DVOM on 200-ohmscale. Disconnect ECA 60-pin connector. Inspect for and repair anydamaged wiring. Install breakout box, then connect ECA to box. Measureresistance between EVP signal at connector and test pin No. 27. Ifreading is 5 ohms or more, repair open circuit. Connect EVP sensor andremove breakout box. Repeat QUICK TEST. If reading is less than 5ohms, go to next step. 4) With key off and EVP harness disconnected, leave breakoutbox installed and ECA disconnected. Set DVOM on 200,000-ohm scale.Measure resistance between EVP signal at EVP connector and ground.Measure resistance between EVP signal at EVP connector and test pinNo. 46. If either reading is less than 10,000 ohms, repair shortcircuit. Connect EVP and remove breakout box. Repeat QUICK TEST. Ifboth reading are 10,000 ohms or more, replace ECA. Connect EVP andremove breakout box. Repeat QUICK TEST. 5) Code 35 Displayed. Turn key off. Disconnect EVP harness atsensor. Inspect for and repair any damaged wiring. Perform KOEO SELF-TEST. Check for code 31. Ignore all other codes at this time. If code31 is not displayed, go to step 7). If code 31 is displayed, go tonext step. 6) With key off and EVP harness disconnected, set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage at EVPharness connector between VREF and signal return. If reading isbetween 4.0 and 6.0 volts, replace EVP sensor. Repeat QUICK TEST. Ifreading is less than 4.0 volts or more than 6.0 volts, go to CIRCUITTEST C, step 1). 7) Turn key off and disconnect EVP from harness. DisconnectECA 60-pin connector. Inspect for and repair any damaged wiring.Install breakout box, leaving ECA disconnected. Set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 27 and test pinsNo. 26 and 57. If either reading is less than 10,000 ohms, repairshort in harness. Connect EVP sensor and remove breakout box. RepeatQUICK TEST. If both readings are 10,000 ohms or more, replace ECA.Connect EVP sensor and remove breakout box. Repeat QUICK TEST. 8) Code 84 Displayed. Turn key off. Set DVOM on 200-ohmscale. Disconnect EVR solenoid connector and measure solenoidresistance. If reading is less than 30 ohms or more than 70 ohms,replace EVR solenoid assembly. Repeat QUICK TEST. If reading isbetween 30 and 70 ohms, go to next step. 9) Leave EVR solenoid disconnected and set DVOM on 20-voltscale. Turn key on, leaving engine off. Measure voltage betweennegative battery terminal and VPWR circuit at solenoid harnessconnector. If reading is less than 10.5 volts, repair VPWR opencircuit. Repeat QUICK TEST. If reading is 10.5 volts or higher, go tonext step. 10) With key off and EVR solenoid disconnected, disconnectECA 60-pin connector. Inspect for and repair any damaged wiring.Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohmscale. Measure resistance between test pin No. 33 and EVR signal atEVR solenoid connector. If reading is 5 ohms or more, repair open

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circuit. Connect EVR solenoid and remove breakout box. Repeat QUICKTEST. If reading is less than 5 ohms, go to next step. 11) With key off, breakout box installed, and ECA and EVRsolenoid disconnected, set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 33 and test pins No. 37, 57, 40, 46and 60 (ground). If any reading is less than 10,000 ohms, repair shortcircuit. Remove breakout box, and connect ECA and EVR solenoid. RepeatQUICK TEST. If code is repeated, replace ECA. If all readings are 10,000 ohms or more, replace ECA. Remove breakout box, and connect ECAand EVR solenoid. Repeat QUICK TEST. 12) Key On/Engine Off Self-Test Code 34 Displayed. Turn keyoff and wait 10 seconds. Install a good known EVP sensor on originalEGR valve. Perform KOEO SELF-TEST. If code 34 is present, check EGRvalve for mechanical malfunction. If code 34 is not present, replaceoriginal EVP sensor. Repeat QUICK TEST.

NOTE: Code 34 indicates that the EGR valve and/or EVP sensor are not fully seated in the closed position. Preload on EVP sensor makes it difficult to determine whether EGR valve is not seated or if the EVP sensor is not in contact with EGR valve stem.

13) KOEO Self-Test Code 32 Displayed. Turn key off and wait10 seconds. Install a known good EVP sensor on original EGR valve.Perform KOEO SELF-TEST. If code 32 is present, check EGR valve formechanical malfunction. If code 32 is not present, replace originalEVP sensor. Repeat QUICK TEST.

NOTE: Code 32 indicates that EGR valve and/or EVP sensor is lower than normal in closed position. Preload on EVP sensor makes it difficult to determine whether the EGR valve has malfunctioned or if the EVP sensor has abnormally high resistance.

14) KOER Self-Test Code 33 Displayed. Turn key off. Usingvacuum "T", connect vacuum gauge at EGR valve. Perform KOER SELF-TESTand observe vacuum gauge. If reading is 1.5 in. Hg or greater, go tostep 17). If reading is less than 1.5 in. Hg, go to next step. 15) Turn key off. Disconnect vacuum source to EVR solenoid.Install vacuum gauge at source vacuum hose. Start engine. If readingis 10 in. Hg or greater, go to next step. If reading is less than 10in. Hg, check vacuum hose to EVR solenoid. Replace if necessary.Repeat QUICK TEST. 16) Carefully check vacuum line for cracks, looseconnections, blockage, kinks, and leaks. If vacuum hose is not okay,replace hose. Connect new vacuum hose and repeat QUICK TEST. If vacuumhose is okay, check EVR solenoid filter for obstructions. Replace ifnecessary. If filter is okay, replace EVR solenoid. Connect all vacuumhoses and repeat QUICK TEST. 17) Turn key off. Wait 10 seconds. Install a good known EVPsensor on original EGR valve. Perform KOER SELF-TEST. If code 33 ispresent, check EGR valve and/or system for mechanical malfunction. Ifno code 33 is present, replace original EVP sensor. Repeat QUICK TEST. 18) KOER Self-Test Code 34 Displayed. Turn key off.Disconnect and plug EGR valve vacuum hose. Perform KOER SELF-TEST. Ifcode 34 is not present, check EVR filter for obstructions. Replace ifnecessary. If filter is okay, replace EVR solenoid. Connect all vacuumhoses and repeat QUICK TEST. If code 34 is present, go to next step. 19) Turn key off. Disconnect harness from EVP sensor. Inspectconnectors for damaged pins or corrosion. Repair if necessary. SetDVOM on 200,000-ohm scale. Disconnect vacuum hose to EGR valve andconnect vacuum pump to valve. Measure resistance between EVP signalreturn and VREF while gradually increasing vacuum to 10 in. Hg. If

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reading decreases from no more than 5500 ohms to no less than 100ohms, check EGR valve for mechanical malfunction. If reading does notchange as indicated, replace EVP sensor. Reconnect vacuum hose. 20) KOER Self-Test Code 38 Displayed. Turn key off.Disconnect vacuum hose at EGR valve and apply 10 in. Hg to EGR valve.If valve holds vacuum for 10 seconds, go to next step. If not, checkEGR valve for mechanical malfunction. Code 38 indicates that EGR valveor EGR vacuum system was unable to maintain a specific opening. 21) Turn key off. Closely inspect vacuum hose from EVRsolenoid to EGR Valve for cracks, loose connections or damage. If hoseis okay, replace EVR solenoid. Repeat QUICK TEST. If hose is damaged,repair or replace as necessary. Repeat QUICK TEST. 22) Turn key off and wait 10 seconds. Ensure vacuum hoses areproperly connected. Carefully check EGR vacuum hose for obstructionskinks, leaks, or damage. If hose is okay, check EVR filter forobstructions. Replace if necessary. If filter is okay, replace EVRsolenoid. Connect vacuum hoses and repeat QUICK TEST. If hose isdamaged, replace hose and repeat QUICK TEST. 23) Continuous Code 32 Displayed. Turn key off and wait 10seconds. Disconnect ECA 60-pin connector. Inspect for and repair anydamaged wiring. Install breakout box and connect ECA. Connect vacuumpump to EGR valve. Place DVOM on 20-volt scale and connect betweentest pins No. 27 and 46. Turn key on, leaving engine off. Observe DVOMreadings. 24) Slowly apply 6 in. Hg vacuum to EGR valve. Slowly bleedvacuum off EGR valve and lightly tap on EVP sensor to simulate roadshock. If any readings are less than 0.29 volts, the EGR valve mayhave caused code 32. Check EGR valve for mechanical malfunction. Ifall readings are more than 0.29 volts, fault cannot be duplicated atthis time. Test is completed. 25) Continuous Code 31 or 35 Displayed. Using CONTINUOUSMONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for faultindication while grasping harness close to sensor and wiggling,shaking, or bending a small section of EEC-IV harness while workingtoward firewall. Also wiggle, shake or bend harness from firewall toECA. If fault is indicated, isolate fault and repair wiring harness asrequired. Repeat QUICK TEST. If fault is not found, go to next step. 26) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector and terminals for obvious damage. Ifconnector and terminals are damaged, repair as necessary. Repeat QUICKTEST. If connector and terminals are okay, fault cannot be duplicatedat this time. Test is completed. 27) Continuous Code 33 Displayed. Turn key off. Connectvacuum pump to EGR valve. Apply 20 in. Hg to EGR valve. If EGR valveopens and holds vacuum, go to next step. If not, check EGR valve formechanical malfunction. 28) Using CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM ordiagnostic tester for fault indication. Grasp harness close to EVRsolenoid connector and wiggle, shake, or bend a small section ofharness while working toward ECA. Inspect connectors and terminals forobvious damage. If fault is indicated, isolate fault and repair asnecessary. Repeat QUICK TEST. If no fault is indicated, fault cannotbe duplicated at this time. Testing is completed. 29) Continuous Code 34 Displayed. Turn key off. Disconnectharness from EVP sensor. Inspect connector for obvious damage. PlaceDVOM on 200,000-ohm scale. Disconnect vacuum hose to EGR valve andconnect vacuum pump to valve. Measure resistance at EVP sensor betweentest pins No. 26 and 27 while increasing vacuum to 10 in. Hg. Ifreading does not decrease gradually, check EGR valve for mechanicalmalfunction. If reading gradually decreases from no more than 5500ohms to no less than 100 ohms, go to next step. 30) Turn key off. Disconnect vacuum hose from EGR valve andplug hose. Perform KOER SELF-TEST. If code 34 is present, check EVR

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filter for obstructions. Replace if necessary. If filter is okay,replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST.If code 34 is not present, fault cannot be duplicated at this time.Testing is completed.

Fig. 17: EGR Valve Position (EVP) & EGR Valve Regulator (EVR) Ckts

TEST N - VSS

VEHICLE SPEED SENSOR (VSS)

To prevent replacement of good components, be aware that thefollowing circuit test is to be used only when continuous codes 27 or29 are displayed. This test checks vehicle speed sensor, wiringharness, and ECA. 1) On Automatic Transmission Equipped Vehicles. Record andclear CONTINUOUS SELF-TEST codes. Warm engine to normal operatingtemperature. While in first gear accelerate moderately to 25 MPH andcoast down to idle and stop. Shut off engine. Perform KEY OFF/ENGINEON (KOEO) SELF-TEST. If code 29 is present. If not, fault cannot beduplicated at this time. If any other codes are present, return toQUICK TEST. If codes are not present, test is completed. 2) On Manual Transmission Equipped Vehicles. Record and clearCONTINUOUS SELF-TEST codes. Warm engine to normal operatingtemperature. Start in first gear, shift to second gear, and acceleratemoderately to 40 MPH. Coast down to idle and stop. Shut engine off.Perform KOEO SELF-TEST. If code 29 is present, go to next step. Ifnot, fault cannot be duplicated at this time. If any other codes arepresent, return to QUICK TEST. If codes are not present, test iscompleted. 3) Turn key off and wait 10 seconds. Disconnect vehicle speedsensor. Set DVOM on 200,000-ohm scale. Measure resistance acrossvehicle speed sensor. If reading is between 190-230 ohms, go to nextstep. If reading is incorrect, replace vehicle speed sensor and repeatstep 1). 4) Turn key off and wait 10 seconds. Remove ECA 60-pinconnector and inspect for damaged pins, corrosion, or loose wires.Repair as necessary. Install breakout box. With ECA and VSSdisconnected, set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 3 at breakout box and VSS harness connector. Also measureresistance between test pin No. 6 at breakout box and VSS harnessconnector. If both readings are 5 ohms or less, go to next step. If

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readings are 5 ohms or more, service open circuit in VSS wiringharness. After repairs, repeat step 1). 5) Turn key off. With ECA and VSS disconnected, set DVOM on200,000-ohm scale. Measure resistance between test pin No. 3 and testpins No. 37, 40 and 6 at breakout box. Also measure resistance betweentest pin No. 6 and test pins No. 37 and 40. If all readings aregreater than 10,000 ohms, go to next step. If any reading is less than10,000 ohms, repair short(S) in VSS wiring harness. After repairs,repeat step 1). 6) Substitute VSS with known good sensor. Connect ECA andVSS. Repeat step 1), then return to this step. If code 29 is present,replace ECA and repeat step 1). If no code is present, replaceoriginal vehicle speed sensor.

Fig. 18: Vehicle Speed Sensor Circuit

TEST O - NEUTRAL A/C SWITCH

NEUTRAL DRIVE SWITCH-A/C INPUT

1) Code 67 Displayed. When this code is displayed, determinewhich engine and system is being tested and proceed to correct step aslisted.

* For 5.0L SEFI models with Man. Trans., go to step 5). * For 5.0L SEFI models with Auto. Trans., go to next step.

2) Turn key off and wait 10 seconds. Make sure heater controlis in "OFF" position and that transmission is in Neutral or Park.Disconnect ECA 60-pin connector. Inspect for and repair any damagedwiring. Install breakout box and connect ECA. Turn key on, leavingengine off. Set DVOM on 20-volt scale. Measure voltage between testpin No. 30 and chassis ground. If reading is less than one volt, go tostep 4). If reading is one volt or more, go to next step. 3) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA connected. Locate Neutral Drive Switch (NDS) anddisconnect harness at switch. Set DVOM on 200-ohm scale and measureresistance across switch. If reading is less than 5 ohms, repair openin NDS circuit. Repeat QUICK TEST. If reading is 5 ohms or more,replace neutral drive switch and repeat QUICK TEST. 4) Ensure A/C is off. If A/C was on, repeat QUICK TEST. Ifcode 67 is still present, install breakout box and disconnect ECA.Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measurevoltage between test pin No. 10 and chassis ground. If reading is 1.0volt or more, repair short to power in A/C clutch circuit. RepeatQUICK TEST. If reading is less than 1.0 volt, replace ECA and repeat

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QUICK TEST. 5) Turn key off and wait 10 seconds. Make sure that A/C isoff (if equipped). Disconnect ECA 60-pin connector. Inspect for andrepair any damaged wiring. Install breakout box and connect ECA. SetDVOM on 200-ohm scale. Measure resistance between test pins No. 30 and46, first with transmission in Neutral and clutch up, and then withtransmission in gear and clutch down. If both readings are less than 5ohms, go to step 4). If any reading is 5 ohms or more, go to nextstep. 6) Turn key off. With breakout box and ECA connected, setDVOM on 200-ohm scale. Locate neutral switch (on transmission) andclutch switch (under dash). Disconnect wiring harness from bothswitches and inspect connectors. Measure resistance across neutralswitch with transmission in Neutral. Measure resistance across clutchswitch with clutch pedal down. If both readings are less than 5 ohms,go to next step. If reading at either switch is 5 ohms or more,replace defective switch. Connect harness and repeat QUICK TEST. 7) Turn key off and wait 10 seconds. Install breakout box andset DVOM to 200-ohm scale. Disconnect harness at neutral switch andclutch switch. Measure resistance between test pin No. 30 and neutralswitch harness connector and between test pin No. 30 and clutch switchharness connector. If both readings are less than 5 ohms, go to step4). If any reading is 5 ohms or more, repair open in harness orconnector. Repeat QUICK TEST. 8) Turn key off and wait 10 seconds. Ensure A/C is off.Disconnect ECA 60-pin connector. Inspect for and repair any damagedwiring. Install breakout box, leaving ECA disconnected. Set DVOM on200-ohm scale. Measure resistance between test pins No. 30 and 46 atbreakout box. If reading is less than 5 ohms, go to step 4). Ifreading is more than 5 ohms, repair open in neutral input and orsignal return circuit. After repairs, repeat QUICK TEST. 9) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector and inspect for damage, corrosion, or loose wires. Repair ifnecessary. Install breakout box, leaving ECA disconnected. Set DVOM on20-volt scale. Turn key and A/C on. Check voltage between pins No. 10and 40 at breakout box. If reading is greater than 10.5 volts, replaceECA and repeat QUICK TEST. If not, repair open in A/C circuit.

Fig. 19: Neutral Drive-A/C Input Circuit (5.0L SEFI Man. Trans.)

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Fig. 20: Neutral Drive-A/C Input Circuit (5.0L SEFI Auto. Trans.)

TEST P - KEY POWER CHECK

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: charging systemovercharging. Battery charger connected with engine running. Jumpstarting vehicle. 1) Turn key off and wait 10 seconds. Install breakout box andconnect ECA. Set DVOM on 20-volt scale and connect to test pins No. 5and 60. During KEY ON/ENGINE RUNNING (KOER) SELF-TEST, observe DVOMand record codes. If reading is above 17.5 volts, repair chargingsystem for overcharging condition. If reading is below 17.5 volts andcode 65 is displayed, replace ECA and repeat QUICK TEST. If reading isbelow 17.5 volts and code 65 is not displayed, go to next step. 2) Continuous Code 65 Displayed. Perform KEY ON/ENGINE OFF(KOEO) SELF-TEST and record service codes. If continuous code 65 isdisplayed, check charging system for intermittent overchargingcondition (above 17.5 volts). If code 65 is not displayed, faultcannot be duplicated at this time. Continuous code 65 testing iscomplete. 3) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox and connect ECA. Set DVOM on 20-volt scale. Measure voltagebetween test pins No. 5 and 60, and perform KOER SELF-TEST. If readingis above 7.5 volts and code 55 is displayed, replace ECA. Repeat QUICK

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TEST. If reading is above 7.5 volts and code 55 is not displayed, goto step 5). If reading drops below 7.5 volts, go to next step. 4) Turn key off. With breakout box installed and ECAconnected, set DVOM on 200-ohm scale. Measure resistance between testpin No. 5 and key power terminal on EEC power relay. If reading is 5ohms or less, check charging system for undercharging condition. Ifreading is more than 5 ohms, repair open in key power circuit andrepeat QUICK TEST. 5) Continuous Code 55 Displayed. Perform KOEO SELF-TEST andrecord service codes. If continuous code 55 is displayed, checkcharging system for intermittent overcharging condition (above 17.5volts). If code 55 is not displayed, fault cannot be duplicated atthis time. Continuous code 55 testing is complete.

Fig. 21: Key Power Circuit

TEST U - CFI FUEL CONTROL

3.8L CFI FUEL CONTROL

NOTE: See HOW TO USE CIRCUIT TESTS before performing this test. Fuel contaminated engine oil may affect service codes 41, 42, 91 and 92. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil and filter.

1) Install breakout box and connect ECA to box. Turn key on.Set DVOM on 20-volt scale and measure resistance between test pin 5and 60. If reading is less than 10.5-volts, service open in key powercircuit. Repeat QUICK TEST. If reading is 10.5-volts or greater, go tonext step. 2) Install fuel pressure gauge. Start and run engine. Fuelpressure must be 35-45 psi (2.5-3.2 kg/cm

). Pressure must remain at35-45 psi (2.5-3.2 kg/cm

) for 60 seconds after key is turned off. Ifengine has a "no start" problem, cycling the key from off to on a fewtimes will build up fuel pressure. If fuel pressure is outside range,check electric fuel pump and fuel pressure regulator. If fuel pressuredoes not remain at 35-45 psi (2.5-3.2 kg/cm

) for 60 seconds, go tostep 6). If fuel pressure is correct, go to next step. 3) With pressure gauge installed, cycle key from off to on afew times to pressurize system. Locate and disconnect fuel pump relay.Crank engine for 5 seconds and take pressure reading immediately aftercranking. If pressure reading is 10-20 psi (0.7-1.4 kg/cm

) aftercranking, EEC system is not at fault for no start condition. If

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problem is rough running, missing, fuel code, or if fuel pressure isincorrect, go to next step.

NOTE: Make sure that fuel is of good quality and not contaminated by air or water as pressure readings may be incorrect with bad or contaminated fuel. Also, pressure drop will be greater when engine is cold than when engine is warm. If coolant is 200

F (93�

C), pressure should drop approximately 10 psi (.7 kg/cm

) in 5 seconds while a pressure drop of 20 psi (1.4 kg/cm

) should occur in 5 seconds with engine coolant at 60�

F (15.6

C).

4) Turn key off. Set DVOM on 200-ohm range. Disconnect ECA60-pin connector. Inspect for and repair any damaged wiring. Installbreakout box, leaving ECA disconnected. Measure resistance betweentest pin 57 and 58, and between test pins 57 and 59. If either readingis less than 1.5 ohms, repair harness and/or connectors on suspectinjector for shorts. If okay, replace injector. If either reading isgreater than 3.5 ohms, repair harness and/or connectors on suspectinjector for opens. If okay, replace injector. If both readings are 1.5 to 3.5 ohms, go to next step. 5) With key off, breakout box installed, and ECA connected,connect a non-powered 12-volt test lamp between test pin 37 and 58.Crank or start engine. Repeat procedure with test lamp between testpin 37 and 59. If test lamp does not light on one or both tests, checkfor 12-volts test pins 37 and 57. If test pins 37 and 57 have 12-volts, replace ECA and repeat QUICK TEST. If test lamp is bright onone or both tests, check circuits to injector banks 1 and 2 for shortto ground. If no short is found, replace ECA and repeat QUICK TEST. Iftest lamp glows dimly on both tests, go to next step.

NOTE: After completing step 6), reset curb idle speed and verify ISC hookup using vehicle emissions label as a guide.

6) Connect tachometer to engine and run engine at idle.Disconnect and connect one injector at a time and note RPM drop foreach injector. If each injector does not produce at least 100 RPM dropwhen disconnected, replace faulty injector(s) and repeat QUICK TEST.If RPM drop is correct for all injectors, fuel delivery is okay,problem is in area common to all cylinders such as a vacuum leak, fuelcontamination, EGR, etc. 7) Code 41 & 91 Displayed. Verify that both codes aredisplayed during QUICK TEST. If code 41 and 91 are not displayed, goto step 8). If both code 41 and 91 are displayed, go to step 9). 8) Turn key off. Swap injector connections. Start engine andperform ENGINE RUNNING SELF-TEST. If original code(s) do not repeat,connect harness to original injectors, then go to step 4). If originalcode(s) repeat, connect harness to original injectors, then go nextstep. 9) Always Lean: Code 41 & 91 Displayed. Code 41 is for rightEGO, code 91 is for left EGO. Turn key off. Set DVOM on 20-volt scale.Disconnect appropriate EGO sensor from vehicle harness. Connect DVOMto EGO sensor and engine block ground. Disconnect ACT sensor. Startand run engine at 2000 RPM. If reading is higher than 0.5-volt withinone minute, go to next step. If reading is not higher than 0.5-voltswithin one minute, replace EGO sensor and repeat QUICK TEST. 10) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox, leaving ECA disconnected. Measure resistance between test pin 49and engine block and between test pin 29 and left EGO sensorconnector. Measure resistance between test pin 44 and engine block andbetween test pin 43 and right EGO sensor connector. If both circuitsare less than 5 ohms, go to next step. If both circuits are not less

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than 5 ohms, repair open circuits as necessary and repeat QUICK TEST. 11) With key off, breakout box installed, and ECAdisconnected, set DVOM on 200,000 ohm scale. Disconnect appropriateEGO sensor at harness. Measure resistance between test pin 29 (leftEGO) and 40, and between test pin 43 (right EGO) and 40. If reading isless than 10,000 ohms, correct cause of resistance to ground andrepeat QUICK TEST. If reading is 10,000 ohms or higher, go to nextstep. 12) Turn key off. Connect EGO sensor. Make certain that ACTsensor is still disconnected. Start and run engine at 2000 RPM for oneminute. Allow engine to return to idle. Perform ENGINE RUNNING SELF-TEST. If code 41 or 91 are still displayed, inspect ECA connector forcorrosion or damaged pins. If okay, replace ECA and repeat QUICK TEST.If code 41 or 91 are not displayed, EGO sensor input circuit is okay.Go to step 13). 13) Reconnect ACT sensor. Repeat QUICK TEST. If code 41 or 91are displayed, replace ECA and repeat QUICK TEST. If code 41 or 91 arenot displayed, go to next step. 14) Always Rich: Code 42 & 92 Displayed. Turn key off andwait 10 seconds. Disconnect appropriate EGO sensor. Using a jumperwire, ground EGO sensor vehicle harness EGO circuit to engine block.Perform ENGINE RUNNING SELF-TEST. If code 41 or 91 are displayed, goto step 16). If code 41 or 91 are not displayed, go to next step. 15) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox and set DVOM on 200-ohm scale. Measure resistance between test pin49 and left EGO engine block ground, and between test pin 44 and rightEGO engine block ground. Also measure resistance between test pin 29and left EGO harness connector, and between test pin 43 and right EGOharness connector. If both circuits are less than 5 ohms, disconnectECA connector and inspect for damage or corrosion. If okay, replaceECA and repeat QUICK TEST. If both circuits are not less than 5 ohms,repair circuit having a resistance greater than 5 ohms. Repeat QUICKTEST. 16) Turn key off and wait 10 seconds. Disconnect vacuum hosefrom MAP sensor. Apply 18 in. Hg vacuum to MAP sensor. If MAP sensorholds vacuum, release vacuum and go to next step. If MAP sensor doesnot hold vacuum, replace MAP sensor. Connect vacuum hose and repeatQUICK TEST. 17) Using vacuum "T", connect vacuum gauge in intake manifoldvacuum hose at MAP sensor. Start engine and note vacuum reading. Turnkey off and wait 10 seconds. Remove "T" and vacuum gauge. Reconnecthose to MAP sensor. Connect vacuum gauge at a different intakemanifold location. Start engine and note vacuum reading. If readingsdiffer by more than 1 in Hg, inspect vacuum hoses for leaks, kinks, orblockage. Repair as required. If readings are within 1 in. Hg of eachother, go to next step. 18) Set DVOM on 20-volt scale. With appropriate EGO sensordisconnected, connect DVOM to EGO sensor and engine ground. DisconnectPCV hose. Start and run engine at 2000 RPM. If reading is less than 0.4-volts within one minute, EGO sensor is okay, go to step 2). Ifreading is not less than 0.4-volts within one minute, replace EGOsensor. Repeat QUICK TEST. 19) Continuous Codes 41 & 42 Displayed. If code 41 isdisplayed, it indicates that system was lean for more than 15 seconds.If code 42 is displayed, it indicates that fuel system was rich formore than 15 seconds. Before attempting to correct a code 41 or 42,diagnose all other complaints such as rough idle, missing, etc. Areasto check to isolate fuel control problems are as follows:

* Vacuum/Air Leaks. Vacuum or intake air leaks in canister purge system, PVC system, or engine sealing. * EGO Sensor Fuel Fouled. If fuel fouled spark plugs are

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observed, make complete check of ignition system. If EGO sensor is fuel fouled (low output and/or slow response), run vehicle at high (but legal) sustained speeds. Follow speed run with a few hard accelerations to burn off contamination and restore EGO sensor to correct operation. * Fuel Pressure. Perform step 2). * Ignition System. If always in default spark (10 degrees), perform TIMING CHECK. * Improper Fueling. Lead fouled EGO sensor. * TPS. If not moving, check for mechanical damage. Connect DVOM to test pins 47 and 46. Turn key on, leaving engine off. Observe DVOM while moving throttle. Reading must increase with throttle opening. If not, replace TPS as necessary. If, at this point, drive problem is still present, perform steps 3) through 6) only.

Fig. 22: 3.8L CFI Fuel Control Circuits

TEST T - FUEL CONTROL

5.0L SEFI FUEL CONTROL

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NOTE: See HOW TO USE CIRCUIT TESTS before performing this test. Fuel contaminated engine oil may affect service codes 41, 42, 91 and 92. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil and filter. Enter CYLINDER BALANCE TEST as specified in step 1). For additional information see QUICK TEST DIAGNOSTIC AIDS, CYLINDER BALANCE TEST in front of this article.

1) Perform KEY ON/ENGINE RUNNING (KOER) SELF-TEST. After lastcode is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST bybriefly opening throttle for one second. If balance test does notdisplay code 90, go to step 6). If balance test displays code 90(Pass), go to next step. 2) Turn key off and wait 10 seconds. Install fuel pressuregauge. Start and run engine. Fuel pressure must be 27-37 psi (1.9-2.6kg/cm

). If engine will not run, cycle key from off to on severaltimes to increase fuel pressure. Pressure must be 35-45 psi (2.5-3.2kg/cm

) with engine off. If fuel pressure is incorrect, check electricfuel pump and fuel pressure regulator. If fuel pressure is correct, goto next step. 3) Turn key on. If fuel pump does not hold pressure for 60seconds, go to step 5). If fuel pump holds pressure for at least 60seconds, go to next step. 4) With key off and pressure gauge installed, cycle key fromoff to on several times to pressurize system. Locate and disconnectinertia switch. Crank engine for 5 seconds and take pressure readingimmediately after cranking engine. If pressure reading drops 5 psi (0.4 kg/cm

) or more after cranking, EEC system is NOT at fault for nostart. If problem is rough running, missing, or fuel code, go to nextstep. If pressure did not drop as indicated, go to step 6).

NOTE: Make sure that fuel is of good quality and not contaminated by air or water, as pressure readings may be incorrect with bad or contaminated fuel. Also, pressure drop will be greater when engine is cold than when engine is warm. If coolant temperature is 200

F (93�

C) pressure should drop approximately 10 psi (0.7 kg/cm

) in 5 seconds while a pressure drop of 20 psi (1.4 kg/cm

) should occur in 5 seconds with engine coolant at 60

F (15.6�

C).

5) Turn key off. Perform KOER SELF-TEST and enter CYLINDERBALANCE TEST by briefly opening throttle for one second immediatelyafter last service code is displayed. If balance test displays code 90(Pass), go to DIAGNOSIS BY SYMPTOM TEST. If balance test does notdisplay code 90, go to next step.

CYLINDER BALANCE TEST SERVICE CODES TABLE�����������������������������������������������������������������������������������������

Service Cylinder/ Breakout BoxCode Injector No. Test Pin No.

90 ............. Pass .............. Pass10 .............. 1 .................. 5820 .............. 2 .................. 5930 .............. 3 .................. 1240 .............. 4 .................. 1350 .............. 5 .................. 1460 .............. 6 .................. 1570 .............. 7 .................. 4280 .............. 8 .................. 5277 ............ Retest ........... Retest

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�����������������������������������������������������������������������������������������

6) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweensuspect injector circuit test pin and test pins No. 37 and 57. Ifreading is not between 15-19 ohms, repair open in harness/connectorson suspect injector circuit. If circuit is okay, replace injector andrepeat QUICK TEST. If reading is between 15-19 ohms, go to next step. 7) With key off, breakout box installed and ECA disconnected,set DVOM on 200,000-ohm scale. Measure resistance between suspectinjector circuit test pin and test pins No. 40 and 60. If reading isless than 10,000 ohms, repair short to ground and repeat QUICK TEST.If resistance is 10,000 ohms or more, go to next step. 8) With key off and breakout box installed, connect ECA tobreakout box. Connect a non-powered 12-volt test light between testpin No. 37 and suspect injector circuit test pin(s). Crank or startengine. If test light glows dimly, replace injector and repeat QUICKTEST and CYLINDER BALANCE TEST. If test light is bright or does notlight, replace ECA. Repeat QUICK TEST and CYLINDER BALANCE TEST. 9) Run engine at 2000 RPM for 2 minutes. Turn key off. Wait10 seconds. Perform KOER SELF-TEST. If code 41 or 91 displays, go tonext step. If code 41 or 91 is not present, go to step 21). 10) Code 41 or 91 Displayed. Turn key off and set DVOM on 20-volt scale. Disconnect appropriate HEGO sensor from vehicle harness.Connect DVOM to HEGO sensor and engine ground. Apply 14 in. Hg vacuumto Manifold Absolute Pressure (MAP) sensor and start engine. Ifreading is less than 0.5 volts, replace HEGO sensor(s) and then repeatQUICK TEST. If reading is more than 0.5 volts, go to next step.

NOTE: Vacuum/air leaks in the following non-EEC related areas may cause code 41 or 91 to be displayed. Check for leaking A/C vacuum actuator and engine vacuum leaks. Check EGR and PCV systems. Check for air leak between airflow meter and throttle body. Check for contaminated HEGO sensor(s). Code 41 is for right HEGO sensor. Code 91 is for left HEGO sensor. Both codes indicate an always lean condition.

11) Turn key off. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale and measure resistance betweentest pin No. 49 and engine block ground. Measure resistance betweentest pin No. 29 and HEGO signal at vehicle harness connector and/ormeasure resistance between test pin No. 43 and HEGO signal at vehicleharness connector. If all readings are higher than 5 ohms, repair openin appropriate circuit and repeat QUICK TEST. If all readings are lessthan 5 ohms, go to next step. 12) Turn key off. Leave breakout box installed and ECAdisconnected. Disconnect appropriate HEGO sensor and set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 29 (right HEGO)and test pin No. 40 and/or between test pin No. 43 (left HEGO) andtest pin No. 40. If any reading is less than 10,000 ohms, correctcause of resistance to ground. Repeat QUICK TEST. If reading is 10,000ohms or higher, go to next step. 13) Turn key off. Disconnect appropriate HEGO sensor and setDVOM on 200,000-ohm scale. Measure resistance between HEGO signal andHEGO power ground circuit at HEGO sensor. See HEGO Sensor CircuitChecks. If reading is 10,000 ohms or higher, go to next step. Ifreading is 10,000 ohms or less, replace appropriate HEGO sensor.Connect MAP sensor vacuum hose and repeat QUICK TEST.

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Fig. 23: HEGO Sensor Circuit Checks

14) Turn key off. Connect ECA and HEGO sensor. Ensure MAPsensor vacuum hose is disconnected and plugged. Apply 10 in. Hg to MAPsensor. Start and run engine at 2000 RPM for one minute. Allow engineto idle. Perform KOER SELF-TEST. If code 41 is still present, checkECA connector for corroded or damaged pins. If connector is okay,replace ECA. Connect MAP sensor vacuum hose and repeat QUICK TEST. Ifcode 41 is not present, connect MAP sensor vacuum hose. HEGO inputcircuit is okay. Go back to step 2). 15) Turn key off and wait 10 seconds. Disconnect appropriateHEGO sensor. Code 42 is for right HEGO sensor. Code 92 is for leftHEGO sensor. Set DVOM on 20-volt scale. Turn key on. Measure voltagebetween HEGO signal and HEGO power ground at HEGO harness connector.If reading is more than 0.5 volts, repair short to power in HEGOcircuit. Repeat QUICK TEST. If reading is less than 0.5 volts, go tonext step. 16) Turn key off and leave HEGO disconnected. Set DVOM on200,000-ohm scale. Measure resistance from key power input to HEGOcircuit at HEGO sensor. If reading is 10,000 ohms or less, replaceHEGO sensor and repeat QUICK TEST. If reading is greater than 10,000ohms, go to next step.

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17) Turn key off and wait 10 seconds. Disconnect appropriateHEGO sensor. Using jumper wire, connect HEGO circuit at HEGO harnessconnector to engine block. Repeat KOER SELF-TEST. If codes 41 or 91are present, remove jumper wire and go to next step. If codes 41 or 91are not present, remove jumper wire. Disconnect ECA connector andinspect for damage. If connector is okay, replace ECA. Repeat QUICKTEST. 18) Turn key off and wait 10 seconds. Disconnect vacuum hosefrom MAP sensor and connect vacuum pump to sensor. Apply 18 in. Hg ofvacuum to MAP sensor. If sensor does not hold vacuum, replace MAPsensor. Connect vacuum hose and repeat QUICK TEST. If MAP holdsvacuum, release vacuum and go to next step. 19) Using vacuum "T", connect vacuum gauge in intake manifoldvacuum hose at MAP sensor. Start engine and note vacuum reading. Turnkey off and wait 10 seconds. Remove "T" and vacuum gauge. Reconnecthose to MAP sensor. Connect vacuum gauge at a different intakemanifold location. Start engine and note vacuum reading. If readingsdiffer by more than 1 in. Hg, inspect vacuum hoses for leaks, kinks,or blockage. Repair as required. If readings are within 1 in. Hg ofeach other, go to next step. 20) Set DVOM on 20-volt scale. With HEGO sensor disconnectedfrom harness, connect DVOM between HEGO sensor and engine ground.Disconnect PCV hose. Start and run engine at 2000 RPM. If reading isless than 0.4 volts within 30 seconds, HEGO sensor if okay. Go back tostep 2). If reading is more than 0.4 volts within 30 seconds, replaceHEGO sensor and repeat QUICK TEST. 21) Turn key on, leaving engine off. Set DVOM on 200-ohmscale. With HEGO disconnected, measure resistance between run circuitand ground at HEGO harness connector. With HEGO sensor hot or warm,resistance should be 5-20 ohms. If HEGO is at room temperature,resistance should be 2-5 ohms. If readings are within specifications,go to next step. If not, replace HEGO sensor. 22) Turn key on, leaving engine off. Set DVOM on 20-voltscale. Connect positive lead to run circuit and negative lead toground at HEGO harness connector. If reading is 10.5 volts or greater,HEGO sensor system is okay. Connect HEGO sensor and go back to step2). If reading is less than 10.5 volts, go to next step. 23) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Measure resistance of ground circuit from HEGO harnessconnector to battery ground. If reading is less than 5 ohms, repairopen in run circuit. If reading is more than 5 ohms, repair open inground circuit.

Fig. 24: 5.0L SEFI Fuel Control Circuits

TEST Y - INERTIA SWITCH

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FUEL PUMP CIRCUIT (INERTIA SWITCH)

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: fuel lines, fuelfilters, throttle body, fuel pump or contaminated fuel. 1) Install fuel pressure gauge. Cycle key from off to onseveral times to check if fuel pump runs. DO NOT crank engine. Pumpshould operate each time key is on. If pump runs as indicated, checkfuel pump for problems. If pump does not run as indicated, go to nextstep. 2) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box and connect ECA. Turnkey on, leaving engine off. Set DVOM on 20-volt scale. Measure voltagebetween test pins No. 37 and 40, and between test pins No. 57 and 60.If either reading is less than 10.5 volts, go to CIRCUIT TEST B, step1). If both readings are 10.5 volts or more, go to next step. 3) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA connected. Locate and disconnect fuel pump inertiaswitch. Set DVOM on 200-ohm scale and measure switch resistance. Ifreading is 5 ohms or more, reset or replace inertia switch. RepeatQUICK TEST. If reading is less than 5 ohms, reconnect inertia switchand go to next step. 4) Turn key on, leaving engine off. Leave breakout boxinstalled and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and power-to-pumpcircuit at fuel pump relay while cranking engine. If reading is lessthan 8 volts, go to step 6). If reading is 8 volts or more, go to nextstep. 5) Turn key on, leaving engine off. Leave breakout boxinstalled and ECA connected. Locate fuel pump. Set DVOM on 20-voltscale. Measure voltage between chassis ground and power-to-pumpcircuit at fuel pump while cranking engine. If reading is 8 volts ormore, repair electric fuel pump. If reading is less than 8 volts,repair open in power-to-pump circuit and repeat QUICK TEST. 6) Turn key on, leaving engine off. Leave breakout boxinstalled and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and V BATT circuitat fuel pump relay. If reading is less than 10.5 volts, repair open inV BATT circuit between fuel pump relay and battery positive post.Repeat QUICK TEST. If reading is 10.5 volts or greater, go to nextstep. 7) Turn key on, leaving engine off. Leave breakout boxinstalled and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and V POWER circuitat fuel pump relay. If reading is 10.5 volts or more, go to next step.If reading is less than 10.5 volts, ensure inertia switch will reset.If inertia switch will not reset, replace switch. If switch is okay,repair open in V POWER circuit between ECA and fuel pump relay. RepeatQUICK TEST. 8) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA connected. With DVOM on 200-ohm scale, measureresistance between fuel pump circuit at pump relay and test pin No. 22at breakout box. If reading is 5 ohms or more, repair open in fuelpump circuit. Repeat QUICK TEST. If reading is less than 5 ohms, go tonext step. 9) Turn key off. Leave breakout box installed and disconnectECA. Disconnect fuel pump relay. With DVOM on 200,000-ohm scale,measure resistance between test pin No. 22 and test pins No. 40 and60. If reading is less than 10,000 ohms, repair short in fuel pumpcircuit. Repeat QUICK TEST. If reading is 10,000 ohms or more, go tonext step. 10) Turn key off and wait 10 seconds. Leave breakout box

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installed. Leave fuel pump relay and ECA disconnected. With DVOM on200,000-ohm scale, measure resistance between test pin No. 22 and testpins No. 37 and 57. If reading is less than 10,000 ohms, repair shortto power in fuel pump circuit. Connect ECA and attempt to startengine. If engine does not start, replace ECA. Repeat QUICK TEST. Ifreading is 10,000 ohms or more, connect fuel pump relay and go to nextstep. 11) Leave breakout box installed and ECA disconnected.Install a jumper wire between test pin No. 22 and test pins No. 40 or60. Set DVOM on 20-volt scale. Turn key on, leaving engine off.Measure voltage between chassis ground and power-to-pump circuit atfuel pump relay. If reading is 10.5 volts or more, replace ECA andrepeat QUICK TEST. If reading is less than 10.5 volts, replace fuelpump relay. Connect ECA and repeat QUICK TEST. 12) Fuel Pump Relay Check. Turn key off. Remove fuel pumprelay. If fuel pump turns off, replace fuel pump relay. Repeat QUICKTEST. If fuel pump does not turn off, repair short to power-to-pumpcircuit.

Fig. 25: Fuel Pump (Inertia Switch) Circuits

TEST Z - EGR ON/OFF CONTROL

NOTE: Code 34 may be result of high volume exhaust vent system reducing backpressure. If this is suspected, perform test in well-ventilated area without exhaust vent connected.

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: air or vacuum leaks,EGR flow restrictions or EGR value.

1) Code 34 Displayed. Use only DVOM, not diagnostic tester,for this step. Turn key off and wait 10 seconds. Set DVOM on 20-voltscale. Connect negative DVOM lead to STO at SELF-TEST connector andpositive lead to positive battery terminal. Insert jumper wire betweenSTI and signal return circuit at SELF-TEST connector. Perform KEY

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ON/ENGINE OFF SELF-TEST until end of CONTINUOUS SELF-TEST code display(DVOM will read zero volts). Depress and release throttle and observeDVOM reading. If DVOM registered high reading, stay in OUTPUT STATECHECK and go to next step. If DVOM did not show high voltage, depressthrottle to WOT and release. If output voltage does not go high, go toCIRCUIT TEST PP, step 12). Leave test equipment hooked up. 2) Set DVOM on 20-volt scale. Connect DVOM positive lead toVPWR circuit at EGR solenoid and negative lead to EGR output circuit.Depress and release throttle several times to cycle EGR solenoidoutput on and off. If output does not cycle on and off, remove STIjumper wire and go to step 5). If output cycles on and off, go to nextstep. 3) Connect vacuum pump to solenoid vacuum supply port andvacuum gauge to output port of solenoid. Apply minimum vacuum of 6 in.Hg. Depress and release throttle several times to cycle EGR solenoidoutput while maintaining vacuum at supply port. Note gauge reading. Ifvacuum output does not cycle, replace EGR solenoid and repeat QUICKTEST. If vacuum output cycles, go to next step. 4) With vacuum lines disconnected at EGR solenoid, startengine. If vacuum is present, EEC system is not cause of problem.Check exhaust gas recirculation system. If vacuum is not present,correct vacuum source blockage or leak and repeat QUICK TEST. 5) Turn key off and wait 10 seconds. Disconnect EGR solenoid.Set DVOM on 200-ohm scale and measure solenoid resistance. If readingis less than 65 ohms or more than 110 ohms, replace EGR solenoid andrepeat QUICK TEST. If reading is between 65 and 110 ohms, go to nextstep. 6) Turn key on, leaving engine off. Set DVOM on 20-voltscale. Measure voltage between VPWR circuit at EGR solenoid harnessconnector and battery ground. If reading is less than 10.5 volts,repair open in harness and repeat QUICK TEST. If reading is 10.5 voltsor higher, go to next step. 7) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 35 and EGR circuit at connector. If reading is 5 ohms orhigher, repair open circuit and repeat QUICK TEST. If reading is lessthan 5 ohms, go to next step. 8) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Disconnect EGR solenoid. Set DVOM on200,000-ohm scale. Measure resistance between test pin No. 35 and testpins No. 40, 46, and 60. If any reading is less than 10,000 ohms,repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step. 9) Turn key off and wait 10 seconds. Leave breakout boxinstalled. Disconnect ECA and EGR solenoid. With DVOM on 200,000-ohmscale, measure resistance between test pin No. 35 and test pins No. 37and 57. If any reading is less than 10,000 ohms, repair short to powerand repeat QUICK TEST. If code is still repeated, replace ECA. If allreadings are 10,000 ohms or more, replace ECA. Repeat QUICK TEST.

Fig. 26: EGR ON/OFF Circuit

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TEST BB - AIR MANAGEMENT SYSTEM

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: thermactor air systemdrive belt, air pump or valve. 1) Codes 44 (94), 45 (95) & 46 (96) Displayed. Check forcorrect vacuum hose routing to TAB/TAD solenoids and by-pass divertervalve. Use vehicle emissions label as a guide. Check for kinked orblocked vacuum hoses. Check for kinked or blocked air hoses. Check fordisconnected vacuum hoses. If problems are detected, correct hoserouting, repair faults and repeat QUICK TEST. If hoses are good andcode 44 (94) is displayed, go to step 4). If code 46 (96) isdisplayed, go to step 3). If code 45 (95) is displayed, go to nextstep. 2) Code 45 (95) Displayed. This step checks TAD solenoidonly. Disconnect and plug vacuum hose at diverter valve. Turn key offand wait 10 seconds. Repeat KEY ON/ENGINE RUNNING (KOER) SELF-TEST andrecord codes. If code 45 (95) is displayed, EEC system is okay. Checkdiverter valve and/or check valve for problem. If code 45 (95) is notdisplayed, go to step 4). 3) Code 46 (96) Displayed. This step checks TAB solenoidonly. Disconnect and plug vacuum hose at by-pass valve. Turn key offand wait 10 seconds. Repeat KOER SELF-TEST and record codes. If code46 (96) is displayed, EEC system is okay. Check by-pass valve forproblem. If code 46 (96) is not displayed, go to next step. 4) Use only DVOM, not diagnostic tester, for this step. Turnkey off and wait 10 seconds. With DVOM on 20-volt scale, connect DVOMnegative test lead to STO circuit at SELF-TEST connector and positivetest lead to battery positive terminal. Using jumper wire, connect STIcircuit to signal return at SELF-TEST connector. Perform KEY ON/ENGINEOFF (KOEO) SELF-TEST until end of CONTINUOUS SELF-TEST codes (DVOMreads zero volts). Depress and release throttle. DVOM should change toa high voltage reading. If reading changed, remain in OUTPUT STATECHECK and go to next step. If reading did not change, depress throttleto WOT and release. If STO voltage does not go high, go to CIRCUITTEST PP, step 14). Leave test equipment hooked up. 5) Set DVOM on 20-volt scale. Connect DVOM positive test leadto VPWR circuit and negative test lead to TAB circuit at TAB solenoid.While observing DVOM, depress and release throttle several times tocycle output on and off. Repeat for TAD solenoid. Connect positivetest lead to VPWR circuit and negative test lead to TAD circuit at TADsolenoid. Cycle output on and off. If either solenoid does not cycleon and off, remove jumper and go to step 8). If both solenoids cycleon and off, go to next step. 6) Connect vacuum pump to TAB solenoid vacuum supply port.Connect vacuum gauge to output port. Maintain vacuum at source whiledepressing and releasing throttle to cycle output on and off. Observevacuum gauge. Repeat for TAD solenoid. If either output does not cycleon and off, replace TAB/TAD solenoid assembly and repeat QUICK TEST.If both outputs cycle on and off, go to next step. 7) With vacuum hoses disconnected at TAB/TAD solenoidassembly, start engine and check for vacuum. If vacuum is present, EECsystem is okay. Check thermactor valve and air pump for problems. Ifno vacuum is present, repair blockage as required and repeat QUICKTEST. 8) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Disconnect TAB and TAD solenoid connectors. Measure resistanceof both solenoids. If either reading is less than 50 ohms or more 100ohms, replace TAB/TAD solenoid assembly and repeat QUICK TEST. If bothreadings are between 50 and 100 ohms, connect TAB and TAD solenoids.Go to next step. 9) Turn key on, leaving engine off. Set DVOM on 20-volt

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scale. Measure voltage between TAB solenoid VPWR circuit and batteryground. Repeat for TAD solenoid. If either voltage reading is lessthan 10.5 volts, repair harness circuit open and repeat QUICK TEST. Ifboth readings are higher than 10.5 volts, go to next step. 10) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Install breakout box, leaving ECA disconnected. With DVOM on200-ohm scale, measure resistance between test pin No. 51 and TABcircuit at harness connector. Measure resistance between test pin No.11 and TAD circuit at harness connector. If either reading is 5 ohmsor higher, repair harness open circuit and repeat QUICK TEST. If bothreadings are less than 5 ohms, go to next step. 11) Turn key off and wait 10 seconds. Set DVOM on 200,000-ohmscale. Leave breakout box installed and ECA disconnected. DisconnectTAB and TAD solenoids, and measure resistance between test pin No. 51and test pins No. 40, 46 and 60. Also measure resistance between testpin No. 11 and test pins No. 40, 46 and 60. If any reading is lessthan 10,000 ohms, repair short to ground. Remove breakout box, connectharness to ECA, and repeat QUICK TEST. If all readings are 10,000 ohmsor more, go to next step. 12) Turn key off and wait 10 seconds. Set DVOM on 200,000-ohmscale. Leave breakout box installed and ECA disconnected. DisconnectTAB and TAD solenoids, and measure resistance between test pin No. 51and test pins No. 37 and 57 and between test pin No. 11 and test pinsNo. 37 and 57. If any reading is less than 10,000 ohms, repair shortto power. Remove breakout box, connect harness to ECA and repeat QUICKTEST. If code is repeated, replace ECA. If all readings are 10,000ohms or more, replace ECA and repeat QUICK TEST.

Fig. 27: Air Management Circuits

TEST CC - CANP CHECK

CANISTER PURGE (CANP) CHECK

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1) Use only DVOM, not diagnostic tester, for this step. Turnkey on, engine off. Set DVOM on 20-volt scale. Connect DVOM negativetest lead to STO and positive test lead to positive battery terminal.Using jumper wire, connect STI circuit to signal return at SELF-TESTconnector. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST until end ofCONTINUOUS SELF-TEST codes (DVOM reads zero volts). Depress andrelease throttle. DVOM should change to a high voltage reading. Ifreading did not change, depress throttle to WOT and release. If STOvoltage does not go high, go to CIRCUIT TEST PP, step 12). Leave testequipment hooked up. If reading changed, remain in OUTPUT STATE CHECKand go to next step. 2) Set DVOM on 20-volt scale. Disconnect CANP solenoid.Connect DVOM positive test lead to VPWR circuit and negative test leadto CANP output circuit on harness connector. While observing DVOM,depress and release throttle several times to cycle output on and off.If CANP circuit does not cycle on and off, remove jumper wire and goto step 6). If CANP circuit cycles, go to next step. 3) Turn key on. Leave CANP solenoid disconnected. Disconnectvacuum hose from canister purge solenoid on PCV side. Apply 16 in. Hgvacuum to CANP solenoid. If CANP solenoid does not hold vacuum for 20seconds, replace it and repeat QUICK TEST. If fault is still present,service fuel evaporation system. If CANP holds vacuum for 20 seconds,leave vacuum pump attached and go to next step. 4) While still in OUTPUT STATE CHECK, turn CANP circuit off(no voltage). Reconnect CANP solenoid connector. Apply 16 in. Hgvacuum to CANP solenoid as in step 3). Depress and release throttle.If vacuum is released, remove jumper wire from STI and go to nextstep. If vacuum is not released, replace CANP solenoid and repeatQUICK TEST. 5) Disconnect vacuum hose from canister purge solenoid on PVCside. Start engine. If vacuum is present at vacuum hose, EEC system isokay. Check fuel system. If vacuum is not present at hose, checkvacuum hose for proper routing, kinks, or blockage, If okay, checkengine for cause of low vacuum. 6) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Disconnect CANP solenoid connector and measure solenoidresistance. If reading is between 40-90 ohms, go to next step. Ifreading is incorrect, replace CANP solenoid and repeat QUICK TEST. 7) Key on, engine off. Set DVOM on 20-volt scale. Measurevoltage between VPWR circuit at CANP solenoid harness connector andbattery negative terminal. If reading is 10.5 volts or greater, go tonext step. If reading is less than 10.5 volts, repair open in circuitand repeat QUICK TEST. 8) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Connect breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 31 and CANP harness connector. If reading is less than 5ohms, go to next step. If reading is 5 ohms or more, repair opencircuit. Repeat QUICK TEST. 9) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Set DVOM on 200,000-ohm scale and disconnectCANP solenoid. Measure resistance between test pin No. 31 and testpins No. 40, 46, and 60. If all readings are 10,000 ohms or more, goto next step. If any reading is less than 10,000 ohms, repair short toground. Repeat QUICK TEST. 10) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Set DVOM on 200,000-ohm scale and disconnectCANP solenoid. Measure resistance between test pin No. 31 and testpins No. 37 and 57. If all reading are 10,000 ohms or more, removebreakout box. Replace ECA and repeat QUICK TEST. If any reading isless than 10,000 ohms, repair short to power and repeat QUICK TEST. Ifcode is repeated, replace ECA and repeat QUICK TEST.

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Fig. 28: Canister Purge (CANP) Circuit

TEST DD - IDLE SPEED CONTROL

IDLE SPEED CONTROL (AIR BY-PASS)

NOTE: If engine is running rough or has rough idle, correct these conditions before performing test. Causes may be in ignition system, fuel system or EGR system. If fuel system problems are encountered, go to CIRCUIT TEST T, step 1) through 9).

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: engine temperaturenot up to operating temperature, engine over operating temperature,A/C input (electrical problem), improper idle speed/throttle stopadjustment or cruise control linkage. 1) Turn key off. Connect engine tachometer and start engine.Disconnect Idle Speed Control (ISC) harness. If RPM drops or if enginestalls, go to next step. If not, go to step 3). 2) If EGR service codes 31, 32, 33 or 34 are displayed, goto KEY ON/ENGINE RUNNING (KOER) SELF-TEST table and performappropriate CIRCUIT TEST. If these codes are not displayed, go to nextstep. 3) If service codes 22, 41, 42, 33, or 34 are displayed, goto KOER SELF-TEST table and perform appropriate CIRCUIT TEST. If thesecodes are not displayed, go to next step. 4) Turn key off. Disconnect ISC solenoid. Set DVOM on 200-ohmscale, and measure resistance of ISC solenoid. If resistance isbetween 7 and 13 ohms, go to next step. If resistance is less than 7ohms or more than 13 ohms, replace ISC solenoid and repeat QUICK TEST. 5) With key off and ISC harness disconnected, set DVOM on200,000-ohm scale. Measure resistance from either ISC pin to ISCsolenoid housing. If reading is greater than 10,000 ohms, go to nextstep. If reading is 10,000 ohms or less, replace ISC solenoid. RepeatQUICK TEST. 6) Leave ISC harness disconnected. Turn key on, leaving

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engine off. Measure voltage between VPWR circuit at ISC harnessconnector and battery ground terminal. If reading is less than 10.5volts, repair open in circuit and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step. 7) Turn key off and wait 10 seconds. Leave ISC harnessdisconnected. Disconnect ECA 60-pin connector. Inspect connector fordamaged pins, corrosion, or loose wires. Repair if necessary. Installbreakout box, leaving ECA disconnected. With DVOM on 200-ohm scale,measure resistance between test pin No. 21 and ISC circuit at ISCharness connector. If reading is greater than 5 ohms, repair opencircuit and repeat QUICK TEST. If reading is less than 5 ohms, go tonext step. 8) Turn key off and wait 10 seconds. Leave ISC harnessdisconnected. Install breakout box, leaving ECA disconnected. Set DVOMon 200,000-ohm scale. Measure resistance between test pin No. 21 andtest pins No. 40, 46, and 60. If any reading is less than 10,000 ohms,repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step. 9) Turn key off and wait 10 seconds. Leave breakout boxinstalled. Leave ECA and ISC solenoid disconnected. Set DVOM on 200,000-ohm scale. Measure resistance by connecting DVOM negative lead totest pin No. 21 and positive lead to test pin No. 37. If reading isgreater than 10,000 ohms, go to next step. If reading is 10,000 ohmsor less, repair short to power and repeat QUICK TEST. If code orsymptom are still present, replace ECA. 10) With key off, connect ECA and ISC. Leave breakout boxinstalled and set DVOM on 20-volt scale. Connect DVOM between testpins No. 21 and 40. Start engine and observe DVOM while slowlyincreasing and decreasing engine RPM. If DVOM reading varies, go tonext step. If DVOM reading does not vary, replace ECA and repeat QUICKTEST. 11) Verify curb idle speed. If curb idle speed is withinspecifications, replace ISC and repeat QUICK TEST. If curb idle speedis incorrect, check engine vacuum hoses for proper routing. Useemission label as a guide. Ensure throttle plates are fully closed.Check throttle and/or cruise control linkage for binding. Repair ifnecessary. If these items are okay, replace ISC and repeat QUICK TEST. 12) Turn key off and wait 10 seconds. Deactivate SELF-TEST.Start and run engine at 2000 RPM for 2 minutes or until top radiatorhose is hot and pressurized. Turn key off and wait 10 seconds. PerformKOER SELF-TEST. If code 17 is displayed, inspect throttle body and airinlet for contamination. Clean if necessary. If okay, adjust curb idlespeed and repeat QUICK TEST. If code 17 is not displayed, serviceother codes as necessary. 13) Code 13, High RPM Check. Turn key off. Connect tachometerto engine. Start engine. With engine running, disconnect ISC harnessconnector. If engine RPM drops or if engine stalls, replace ECA andrepeat QUICK TEST. If engine RPM does not drop, check engine vacuumhoses for proper routing. Use emission label as a guide. Ensure curbidle is correct. Make sure throttle plates are fully closed. Checkthrottle and/or cruise control linkage for binding. Repair ifnecessary. If these items are okay, replace ISC and repeat QUICK TEST. 14) Code 48 Displayed. Check for and repair holes, cracks,and/or bad connections at air cleaner outlet tube (between vaneairflow meter and fuel charging assembly). Perform KEY ON/ENGINERUNNING SELF-TEST. If code 48 is displayed, check for other sources ofunmetered air. If code 48 is not displayed, EEC system is okay, go toENGINE RUNNING SELF-TEST table and service other codes as necessary.

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Fig. 29: Idle Speed Control (Air By-Pass) Circuit

TEST FF - SHIFT INDICATOR LIGHT

1) Use DVOM, not diagnostic tester, for this step. Turn keyoff and wait 10 seconds. Put transmission in Neutral. Set DVOM on 20-volt scale. Connect DVOM negative test lead to STO at SELF-TESTconnector and positive test lead to positive battery terminal. Installa jumper wire between STI and signal return at SELF-TEST connector.Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST until end of CONTINUOUSSELF-TEST codes (DVOM reads zero volts). Depress and release throttlewhile watching DVOM reading. If reading did not change to a highvoltage, depress throttle to WOT position and release. If STO voltagedoes not go to high reading, go to step 7). Leave test equipmenthooked up. If reading changes to high voltage, remain in OUTPUT STATECHECK and go to next step. 2) Set DVOM on 20-volt scale. Connect DVOM positive test leadto battery positive terminal and negative test lead to pin No. 1 ondimmer relay. Depress and release throttle several times to cyclerelay on and off. If relay does not cycle, go to step 5). If relaycycles, go to next step. 3) Set DVOM on 20-volt scale. Connect DVOM positive test leadto battery positive terminal and negative test lead to pin No. 2 ondimmer relay. Depress and release throttle several times to cyclerelay on and off. If relay does not cycle, remove jumper wire andreplace dimmer relay. If relay does cycle, remove jumper wire and goto next step. 4) Turn key off and wait 10 seconds. With DVOM set to 200-ohmscale, measure resistance between pin No. 2 of dimmer relay and SILbulb. If reading is less than 5 ohms, replace SIL bulb. If reading is5 ohms or more, repair open circuit in harness. Repeat QUICK TEST. 5) Set DVOM on 20-volt scale. Connect DVOM positive test leadto battery positive terminal and negative test lead to SIL circuit oftop gear switch. Depress and release throttle several times to cycleSIL circuit on and off. If SIL circuit cycles, repair open circuit inharness and repeat QUICK TEST. If SIL circuit does not cycle, go tonext step. 6) Set DVOM on 20-volt scale. Connect DVOM positive test leadto positive battery terminal and negative test lead to STO circuit oftop gear switch. Depress and release throttle several times to cycleSTO circuit on and off. If STO circuit cycles, replace top gearswitch. If STO does not cycle, repair open circuit in harness andrepeat QUICK TEST.

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7) Use only VOM/DVOM, not diagnostic tester, for this step.Turn key off and wait 10 seconds. Put transmission in top gear. SetDVOM on 20-volt scale. Connect DVOM negative test lead to STO at SELF-TEST connector and positive test lead to positive battery terminal.Install a jumper wire between STI and signal return at SELF-TESTconnector. Perform KOEO SELF-TEST until end of CONTINUOUS SELF-TESTcodes (DVOM reads zero volts). Depress and release throttle whilewatching DVOM reading. If reading changed to high voltage, check SILbulb and fuse No. 15. If bulb and fuse are good, repair short toground in SIL circuit. If reading did not change to high voltage, goto CIRCUIT TEST PP, step 12).

Fig. 30: Shift Indicator Light (SIL) Circuits

TEST GG - A/C CUT-OUT (WAC)

WIDE OPEN THROTTLE A/C CUT-OUT (WAC) A/C DEMAND

1) Use only DVOM, not diagnostic tester, for this step. Turnkey off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOMnegative test lead to STO at SELF-TEST connector and positive testlead to positive battery terminal. Install a jumper wire between STIand signal return at SELF-TEST connector. Perform KEY ON/ENGINE OFF(KOEO) SELF-TEST until end of CONTINUOUS SELF-TEST codes (DVOM readszero volts). Depress and release throttle while watching DVOM reading.If reading did not change to a high voltage, depress throttle to WOTposition and release. If STO voltage does not go to high reading, goto CIRCUIT TEST PP, step 12). Leave test equipment hooked up. Ifreading changes to high voltage, remain in OUTPUT STATE CHECK and goto next step. 2) Turn key on, leaving engine off. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakout

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box and connect ECA to box. Place A/C switch on A/C position and setDVOM on 20-volt scale. Connect DVOM positive test lead to test pin No.37 and negative test lead to test pin No. 54. Depress and releasethrottle several times while watching DVOM. If A/C clutch outputcycles, EEC system is okay. Check A/C system operation. If A/C clutchoutput does not cycle, remove jumper wire and go to next step. 3) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Disconnect WAC relay and measure relay resistance. If readingis less than 50 ohms or more than 70 ohms, replace WAC relay andrepeat QUICK TEST. If reading is between 50 and 70 ohms, connect WACrelay and go to next step. 4) Turn key on, leaving engine off. Set DVOM on 20-voltscale. Connect DVOM positive test lead to VPWR circuit and negativetest lead to ground. Measure VPWR voltage at WAC relay. If reading isless than 10.5 volts, repair open in harness and repeat QUICK TEST. Ifreading is 10.5 volts or more, go to next step. 5) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect for and repair any damaged wiring. Install breakoutbox, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measureresistance between test pin No. 54 and WAC circuit at relay connector.If reading is 5 ohms or more, repair open in harness and repeat QUICKTEST. If reading is less than 5 ohms, go to next step. 6) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 54 and test pins No. 40, 46, and 60.If any reading is less than 10,000 ohms, repair short to ground andrepeat QUICK TEST. If all readings are 10,000 ohms or more, go to nextstep. 7) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Set DVOM on 200,000-ohm scale. DisconnectWAC solenoid and measure resistance between test pin No. 54 and testpins No. 37 and 57. If all readings are greater than 10,000 ohms, goto next step. If any reading is 10,000 ohms or less, repair short topower and repeat QUICK TEST. If symptom is still present, replace ECA. 8) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltagebetween test pins No. 10 and 40. If output cycle goes from low to high(10.5 volts or more) as A/C switch is cycled, replace ECA and repeatQUICK TEST. If reading does not cycle, repair open in A/C input totest pin No. 10 and repeat QUICK TEST. 9) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 20-volt scale. Measure voltage between testpin No. 10 and test pin No. 40. If output cycles between 4.0 and 10.5volts when A/C switch is cycled, replace ECA. Repeat QUICK TEST. Ifoutput does not cycle, go to next step. 10) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Measure resistance between test pin No. 10 and A/C clutch. Ifany reading is 5 ohms or more, repair harness. Repeat QUICK TEST. Ifreading is less than 5 ohms, EEC is okay. Check A/C system.

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Fig. 31: 5.0L SEFI Engine WOT A/C Cut-Out Circuits

TEST JJ - CCO

CONVERTER CLUTCH OVERRIDE (CCO)

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1) Turn key off and wait 10 seconds. Set DVOM on 200-ohmscale. Disconnect CCO solenoid connector and measure solenoidresistance. If reading is less than 26 ohms or higher than 40 ohms,replace CCO solenoid and repeat QUICK TEST. If reading is between 26and 40 ohms, connect solenoid and go to next step. 2) Turn key on, leaving engine off. With DVOM on 20-voltscale, measure voltage at CCO solenoid connector between VPWR circuitand ground. If reading is 10.5 volts or less, repair open circuit inharness and repeat QUICK TEST. If reading is 10.5 volts or higher, goto next step. 3) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 53 and CCO circuit at solenoid harness connector. Ifreading is 5 ohms or higher, repair open circuit in harness and repeatQUICK TEST. If reading is less than 5 ohms, go to next step. 4) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Disconnect CCO solenoid. Set DVOM on200,000-ohm scale. Measure resistance between test pin No. 53 and testpins No. 40, 46, and 60. If any reading is less than 10,000 ohms,repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or higher, go to next step. 5) Turn key off and wait 10 seconds. Leave breakout boxinstalled, ECA and CCO solenoid disconnected. Set DVOM on 200,000-ohmscale. Measure resistance between test pin No. 53 and test pins No. 37and 57. If all readings are 10,000 ohms or higher, replace ECA andrepeat QUICK TEST. If any reading is less than 10,000 ohms, repairshort to power and repeat QUICK TEST. If code is repeated, replaceECA.

Fig. 32: CCO Circuit

TEST KK - CCO & 3/4,4/3 SHIFT

CONVERTER CLUTCH OVERRIDE (CCO) & 3/4-4/3 SHIFT SOLENOID

This circuit test is used to diagnose CCO shift solenoid

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circuit, CCO solenoid, 3/4-4/3 shift solenoid, and ECA.

1) Code 88 Displayed. Turn key off and wait 10 seconds. SetDVOM on 200-ohm scale. Disconnect CCO solenoid harness connector andmeasure solenoid resistance at transmission bulkhead connector. Ifreading is between 26-40 ohms, connect CCO solenoid and go to nextstep. If reading is incorrect, diagnose operation of transmissionconverter clutch. 2) Turn key on, leaving engine off. Set DVOM on 20-voltscale. Measure voltage at CCO solenoid harness connector between VPWRcircuit and battery negative terminal. If reading is greater than 10.5volts, go to next step. If reading is incorrect, repair open circuitin wiring harness and repeat QUICK TEST. 3) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Disconnect CCO solenoid harness connector attransmission bulkhead connector. Set DVOM on 200-ohm scale. Measureresistance between test pin No. 53 and CCO circuit at solenoid harnessconnector. If reading is less than 5 ohms, go to next step.If not, repair open circuit in wiring harness and repeat QUICK TEST. 4) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Disconnect CCO solenoid harnessconnector at transmission bulkhead connector. Set DVOM on 200,000-ohmscale. Measure resistance between test pin No. 53 and test pins No.40, 46 and 60. If reading is greater than 100,000 ohms, go to nextstep. If not, repair short to ground and repeat QUICK TEST. 5) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Disconnect CCO solenoid harnessconnector at transmission bulkhead connector. Set DVOM on 200,000-ohmscale. Measure resistance between test pin No. 53 and test pins No. 37and 57. If all readings are greater than 10,000 ohms, replace ECA andrepeat QUICK TEST. If not, repair short to power and repeat QUICKTEST. If code is still repeated, replace ECA. 6) Code 85 Displayed. Turn key off and wait 10 seconds. SetDVOM on 200-ohm scale. Disconnect 3/4-4/3 shift solenoid harnessconnector. Measure solenoid resistance at transmission bulkheadconnector. If reading is between 26-40 ohms, connect solenoid and goto next step. If reading is incorrect, diagnose operation oftransmission converter clutch. 7) Turn key on, leaving engine off. Set DVOM on 20-voltscale. Measure voltage between VPWR circuit at 3/4-4/3 shift solenoidharness connector and battery negative terminal. If reading is morethan 10.5 volts, go to next step. If not, repair open circuit inwiring harness and repeat QUICK TEST. 8) Turn key off and wait 10 seconds. Install breakout box,leaving ECA disconnected. Disconnect 3/4-4/3 shift solenoid harnessconnector at transmission bulkhead connector. Set DVOM on 200-ohmscale. Measure resistance between test pin No. 53 and 3/4-4/3 shiftsolenoid circuit at harness connector. If reading is less than 5 ohms,go to next step. If not, repair open circuit in wiring harness andrepeat QUICK TEST. 9) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. Disconnect 3/4-4/3 shift solenoidharness connector at transmission bulkhead connector. Set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 53 and testpins No. 40, 46, and 60. If all readings are greater than 10,000 ohms,go to next step. If not, repair short to ground and repeat QUICK TEST. 10) Turn key off and wait 10 seconds. Set DVOM on 200,000-ohmscale. Disconnect 3/4-4/3 shift solenoid harness connector attransmission bulkhead connector. Measure resistance between test pinNo. 53 and test pins No. 37 and 57. If both readings are greater than10,000 ohms, replace ECA and repeat QUICK TEST. If not, repair short

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to power in wiring harness and repeat QUICK TEST. If code is stilldisplayed, replace ECA.

Fig. 33: Converter Clutch Override (CCO) & 3/4-4/3 Shift Solenoid Ckt

TEST LL - DYNAMIC RESPONSE TEST

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: person testing EECsystem did not perform brief wide open throttle (WOT) after DynamicResponse code, mechanical engine problems, or engine did not go over2000 RPM. Code 77 Displayed. If vehicle is equipped with 5.0L SEFIengine, perform CIRCUIT TEST T. Repeat KEY ON/ENGINE RUNNING (KOER)SELF-TEST. With SELF-TEST activated, start engine. Code 2 (20 on STARtester) indicates start of test. After Dynamic Response code 1 (10 on

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STAR tester) is displayed, perform brief WOT. Dynamic Response servicecodes will be displayed. If code 77 is still present, replace ECA andrepeat QUICK TEST. If code 77 is not displayed, DYNAMIC RESPONSE TESTpassed. Service other codes (if displayed) as required.

TEST MM - "CHECK ENGINE"

"CHECK ENGINE" LIGHT (MALFUNCTION INDICATOR)

To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: fuses, bulb, orsocket. This circuit test checks STO-MIL circuit and ECA. 1) If vehicle will not start, go to CIRCUIT TEST A, step 1).Verify presence of KEY ON/ENGINE OFF (KOEO) SELF-TEST code 11. If not,repeat QUICK TEST. Turn key off. Disconnect ECA 60-pin connector.Inspect connector for damaged pins, corrosion, or loose wires. Installbreakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale.Connect DVOM between test pins No. 17 and 40. If reading is greaterthan 5 ohms, replace ECA. If reading is less than 5 ohms, repair shortto ground in harness. Check harness from test pin No. 17 to SELF-TESTconnector or to "CHECK ENGINE" light. 2) If vehicle will not start, go to CIRCUIT TEST A, step 1).Verify presence of KOEO SELF-TEST code 11. If not, repeat QUICK TEST.Turn key off. Disconnect ECA 60-pin connector. Inspect connector fordamaged pins, corrosion, or loose wires. Repair if necessary. Installbreakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale.Measure resistance between test pin No. 17 and STO at SELF-TESTconnector. Also measure resistance between test pin No. 17 and "CHECKENGINE" light. If both readings are less than 5 ohms, go to next step.If not, repair open circuit in wiring harness. 3) Check for power to "CHECK ENGINE" light bulb. If powerexists at bulb, replace bulb or socket and go to next step. If nopower exists at socket, check fuse and input circuit, and then go tonext step. 4) Remove breakout box and reconnect ECA to harness. Turn keyto "RUN" position. See if "CHECK ENGINE" light is on. If light is on,malfunction indicator system is okay. If light does not come on,replace ECA.

Fig. 34: "CHECK ENGINE" Light (Malfunction Indicator) Circuit

TEST NN - IDM

IGNITION DIAGNOSTIC MONITOR (IDM)

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To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: ignition module,ignition coil, spark plugs and/or high tension cables, distributor andPIP sensor. 1) Turn key off and wait 10 seconds. Disconnect E-coreignition connector from coil. Disconnect ECA 60-pin connector. Inspectconnector for damaged pins, corrosion, or loose wires. Repair ifnecessary. Install breakout box, leaving ECA disconnected. Set DVOM on200,000-ohm scale. Measure resistance between test pin No. 4 andignition coil negative terminal. If reading is less than 20,000 ohmsor higher than 24,000 ohms, repair open circuit and repeat QUICK TEST.If reading is between 20,000 and 24,000 ohms, go to next step. 2) Turn key off and wait 10 seconds. Leave breakout boxinstalled and ECA disconnected. With DVOM on 200,000-ohm scale,measure resistance between test pin No. 4 and test pins No. 40, 46,and 60. If any reading is less than 10,000 ohms, repair short toground and repeat QUICK TEST. If all readings are 10,000 ohms or more,go to next step. 3) Turn key off and wait 10 seconds. Deactivate SELF-TEST.Using CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostictester for indication of fault while lightly tapping on TFI module andwiggling TFI harness connector. If fault is indicated, disconnect TFIharness. Inspect connector and terminals for damage. If connector andterminals are okay, check TFI ignition system. If no fault isindicated, go to next step. 4) While in CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM ordiagnostic tester for indication of fault while wiggling, shaking, orbending small sections of harness while working from TFI connectortoward firewall. Repeat process from firewall to ECA. Perform thistest to check for faults in the following circuits:

PIP Open/Shorted to Ground ............ Check circuit at test pin #56.SPOUT Shorted to Ground ............... Check circuit at test pin #36.Ignition Ground Open .................. Check circuit at test pin #16.IDM Open to Ground ..................... Check circuit at test pin #4.IDM Shorted to Power ................... Check circuit at test pin #4.

Perform CONTINUOUS MONITOR (WIGGLE) TEST on these circuitsone at a time in order to isolate fault. If fault is indicated,isolate fault and repair harness. Repeat QUICK TEST. If no fault isindicated, go to next step. 5) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion or loosewires. If connector is damaged, repair as necessary and repeat QUICKTEST. If connector is okay, replace ECA. Start and run engine for oneminute. Perform KOER SELF-TEST and observe codes. Connect ECA whenstep is completed.

Fig. 35: IDM Circuit

TEST OO - SPARK TIMING CHECK

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To prevent replacement of good components, be aware that thefollowing non-EEC related areas may be at fault: engine condition(valves, vacuum leaks, valve timing, EGR valve, etc.), PIP sensor, andTFI ignition module. 1) Perform KOER SELF-TEST and verify that SELF-TEST isactivated. Check and record timing while in KOER SELF-TEST. Systemlocks timing and then returns to normal 2 minutes after last servicecode is displayed. If timing is 27-33

, spark timing is correct. Go toKOER SELF-TEST. If timing is not 27-33

, go to next step. 2) Locate Spark Output (SPOUT) connector and open theconnection. Start engine and check for 10

BTDC base timing F 3�

. Ifbase timing is correct, reconnect SPOUT connector and go to next step.If base timing is not correct, adjust base timing. After timing isadjusted, reconnect SPOUT and perform TIMING CHECK. See TIMING CHECKin QUICK TEST (ALL VEHICLES) section of this article. 3) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box. Turn key on, leavingengine off. With DVOM on 20-volt scale, measure voltage between testpins No. 37 and 40, and between test pins No. 57 and 60. If eitherreading is less than 10.5 volts, go to CIRCUIT TEST B, step 1). Ifboth readings are 10.5 volts or more, go to next step. 4) Turn key off and wait 10 seconds. Disconnect harnessconnector at TFI module. With DVOM on 200-ohm scale, measureresistance between test pin No. 36 at breakout box and pin No. 2(SPOUT circuit) at TFI harness connector. If reading is greater than 5ohms, repair open circuit. Connect SPOUT connector and check timing asdescribed in step 1). If reading is 5 ohms or less, go to next step. 5) Leave breakout box installed and TFI harness disconnected.Turn key off and set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 16 at breakout box and pin No. 6 (IGN GRND circuit) atTFI harness connector. If reading is less than 5 ohms, go to CIRCUITTEST A, step 7). If reading is 5 ohms or more, repair harness asnecessary and repeat QUICK TEST.

Fig. 36: Spark Timing Check Circuit

TEST PP - NO CODES/CODES NOT LISTED

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1) No Codes, Codes Not Listed. Turn key off and wait 10seconds. Set DVOM on 20-volt scale. Disconnect Throttle PositionSensor (TPS). Turn key on, leaving engine off. Measure voltage betweenVREF circuit at TPS harness connector and SIG RTN circuit in SELF-TESTconnector. If reading is less than 4 volts or more than 6 volts, go toCIRCUIT TEST C, step 1). If reading is between 4 and 6 volts, connectTPS and go to next step. 2) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 48 and Self-Test Input (STI) at SELF-TEST connectorpigtail. If reading is 5 ohms or more, repair open in circuit. Ifreading is less than 5 ohms, go to next step. 3) With breakout box installed and DVOM on 200-ohm scale,measure resistance between test pin No. 17 and Self-Test Output (STO)at SELF-TEST connector. If reading is 5 ohms or more, repair open incircuit. If reading is less than 5 ohms, go to next step. 4) Turn key off. With breakout box installed and DVOM on 200-ohm scale, measure resistance between test pin No. 49 and EGO sensorengine block ground. If reading is 5 ohms or more, repair EGO sensorground wire or open circuit bad connection. If reading is less than 5ohms, go to next step. 5) With breakout box installed and DVOM on 200-ohm scale,measure resistance between STO at SELF-TEST connector and engine blockground. If reading is 5 ohms or less, repair STO circuit for short toground and repeat QUICK TEST. If reading is greater than 5 ohms, go tonext step. 6) Turn key off. Install breakout box, and connect ECA tobreakout box. Set DVOM on 20-volt scale. Connect DVOM between test pinNo. 30 and test pins No. 40 or 60. Perform KEY ON/ENGINE RUNNING(KOER) SELF-TEST. If reading is greater than one volt, repairintermittent fault in NDS harness connector or switch. If okay, go toKOER SELF-TEST for appropriate service codes. If reading is notgreater than one volt, go to next step. 7) Leave key off and breakout box installed. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 37 or 57 and betweentest pins No. 40 or 60. Turn key on and then off. Wait 10 seconds. Ifreading does not change from 10.5 volts (or higher) to zero volts,replace EEC power relay. Repeat QUICK TEST. If reading changes from10.5 volts (or higher) to zero volts, go to next step only if vehicleis equipped with Malfunction Indicator Light (MIL) or Shift IndicatorLight (SIL). If vehicle is NOT equipped with either of these lights,replace ECA. Repeat QUICK TEST.

NOTE: Malfunction Indicator Light (MIL) is displayed as "CHECK ENGINE" light on instrument cluster.

8) Malfunction Indicator Light (MIL) or Shift Indicator Light(SIL). If shift indicator light is always on or off, go to CIRCUITTEST FF, step 1). If malfunction indicator light is always on, go toCIRCUIT TEST MM, step 1). If malfunction indicator light is alwaysoff, go to CIRCUIT TEST MM, step 2). If MIL or SIL is workingnormally, replace ECA and repeat QUICK TEST. 9) Continuous Code 15 Displayed. Clear continuous memorycodes using procedure outlined in CONTINUOUS SELF-TEST. Repeat KOEOSELF-TEST through continuous memory code output. If continuous code 15is not displayed, continuous code 15 testing is complete. Ifcontinuous code 15 is displayed, go to next step.

NOTE: Continuous code 15 may be displayed when power to Keep Alive Memory (KAM) test pin No. 1 at ECA is interrupted. Code 15 may also be displayed the first time SELF-TEST is performed

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and power is restored to ECA. Repeat SELF-TEST to ensure correct diagnosis.

10) Ensure that EEC components and wiring are not close tohigh tension secondary voltage wires or ignition components. If EECwiring is close to high tension wires, reroute EEC wiring. RepeatQUICK TEST. If continuous code 15 is no longer displayed, continuouscode 15 testing is complete. If continuous code 15 is still displayed,go to next step. 11) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector and inspect for damage. Install breakout box, leaving ECAdisconnected. Set DVOM on 20-volt scale. Connect DVOM positive testlead to test pin No. 1 and negative test lead to pins No. 40 or 60.Turn key on and observe voltage reading. If reading is less than 10.5volts, repair open to KAM circuit. Repeat QUICK TEST. If reading is10.5 volts or more, replace ECA and repeat QUICK TEST. 12) Output State Check Not Functioning. Turn key off and wait10 seconds. Perform KOEO SELF-TEST and leave key on to enter OUTPUTSTATE CHECK. If codes 23, 53, 63 or 68 are displayed, go to KOEO SELF-TEST table and service code(s) as instructed. If no codes aredisplayed, go back to step 1). If code 11 (Pass) is displayed, go tonext step. 13) Check throttle and linkage for sticking or binding. Ifthrottle and linkage are okay, replace TPS and repeat QUICK TEST. Ifthrottle and linkage are binding, repair as necessary and repeat QUICKTEST. 14) Power to ECA Check. Turn key off and wait 10 seconds.Disconnect ECA 60-pin connector. Inspect connector for damaged pins,corrosion, or loose wires. Repair if necessary. Install breakout boxand set DVOM on 20-volt scale. Turn key on, leaving engine off.Measure voltage between test pins No. 37 and 40, and between test pinsNo. 57 and 60. If either reading is less than 10.5 volts, go toCIRCUIT TEST B, step 1). If both readings are 10.5 volts or more,replace ECA and repeat QUICK TEST. 15) Turn key off. Ensure that EEC wiring and components aremore than 2" (50 mm) away from secondary ignition wires. Make surethat EEC wiring and components are more than 4" (100 mm) away fromdistributor, ignition coil, and starter motor and its wiring. If theseitems are correct, go to next step. If not, correct as necessary andrepeat QUICK TEST. 16) Turn key off. Disconnect ECA 60-pin connector. Inspectconnector for damaged pins, corrosion, or loose wires. Repair ifnecessary. Install breakout box, leaving ECA disconnected. Set DVOM on200-ohm scale. Measure resistance between test pin No. 20 and chassisground. If reading is less than 5 ohms, go to next step. If not,repair wiring harness and repeat QUICK TEST. 17) Turn key off. Connect ECA to breakout box, but disconnectharness from breakout box. Set DVOM on 200-ohm scale. Measureresistance between test pin No. 20 and ECA metal case. If reading isless than 5 ohms, go to CIRCUIT TEST B, step 9). If reading is morethan 5 ohms, replace ECA and repeat QUICK TEST.

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Fig. 37: No Codes/Codes Not Listed Circuits

TEST QQ - SYSTEM CHECK

Perform this test ONLY after code 11 is displayed in KEYON/ENGINE OFF (KOEO) SELF-TEST and you have been directed here fromCIRCUIT TEST A, step 14) or by DIAGNOSIS BY SYMPTOM TEST. 1) ISC Check. If you are here for any reason other thanengine stall or no start, go to next step. If engine stalls or if itdoes not start, attempt to start engine at part throttle. If engineruns roughly, go to next step. If engine runs smoothly at partthrottle, go to CIRCUIT TEST DD, step 4). If engine does not run, goto step 2). 2) MAP Check. Turn key off and disconnect MAP sensor. ConnectMAP tester between harness and MAP sensor. Connect banana plugs oftester into DVOM and set DVOM on 20-volt scale. Turn key on and

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measure sensor output voltage while cranking engine. If DVOM readingdoes not decrease from specified range, go to CIRCUIT TEST H, step14). If DVOM reading decreases from specified range, go to next step.

MAP VOLTAGE OUTPUT TABLE�����������������������������������������������������������������������������������������

Elevation (Ft.) Voltage Output (Volts)

0 ............................ 1.55-1.631000 ............................ 1.52-1.602000 ............................ 1.49-1.573000 ............................ 1.46-1.544000 ............................ 1.43-1.515000 ............................ 1.40-1.486000 ............................ 1.37-1.457000 ............................ 1.35-1.43�����������������������������������������������������������������������������������������

3) EGR Check. Disconnect and plug vacuum hose at EGR valve.Ensure that EGR valve is closed. Start or attempt to start engine. Ifsymptom is eliminated or if no start is resolved, go to CIRCUIT TESTM, step 22). If symptom is NOT eliminated or if engine will NOT start,go to CIRCUIT TEST T, step 1).

TEST RR

AXOD TRANSAXLE

NOTE: Perform this test only when KEY ON/ENGINE OFF (KOEO) SELF- TEST service codes 62, 67, and 89 are present; when KEY ON/ENGINE RUNNING (KOER) SELF-TEST service code 62 is displayed; or when CONTINUOUS SELF-TEST service codes 29, 39, 57, 59, and 69 are displayed. Ensure that ALL components are connected before performing test.

AXOD Drive Cycle Test. Record and zero continuous memoryservice codes. Warm engine to operating temperature. With transaxle in"D" range, lightly accelerate from a stop to 40 MPH to allow transaxleto shift into 3rd gear. Hold speed and throttle opening steady for aminimum of 15 seconds (30 seconds above 4000 feet altitude). Shift transaxle into overdrive and accelerate lightly from 40to 50 MPH to allow transaxle to shift into 4th gear. Hold speed andthrottle opening steady for a minimum of 15 seconds. With transaxle in 4th gear, throttle open and speed steady,lightly apply and release brakes (enough to turn on brake lights).Hold speed and throttle opening steady for an additional 15 seconds. Brake to a stop and remain stopped for a minimum of 20seconds with transaxle in overdrive. Perform QUICK TEST and recordcontinuous memory service codes. 1) Continuous Code 29 Displayed. Perform AXOD DRIVE CYCLETEST and return to this step. If continuous code 29 is not displayed,fault cannot be duplicated at this time. If any other codes arepresent, return to QUICK TEST for instructions. If there are none,test is complete. If continuous code 29 is displayed, go to next step. 2) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECA andVehicle Speed Sensor (VSS) disconnected. Set DVOM on 200-ohm scale.Measure resistance between test pin No. 3 and VSS + circuit at harnessconnector. Measure resistance between test pin No. 6 and VSS - circuitat harness connector. If both readings are 5 ohms or more, repairopen(s) in VSS harness, then repeat step 1). If both readings are 5

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ohms or less, go to next step. 3) With key off, ECA and VSS disconnected, set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 3 and test pinsNo. 37, 40, and 6. Then measure resistance between test pin No. 6 andtest pins No. 37 and 40. If all readings are less than 1000 ohms,repair short(s) in VSS harness, then repeat step 1). If all readingsare more than 1000 ohms, go to next step. 4) Substitute original VSS with a good known VSS. With ECAand VSS connected, perform AXOD DRIVE CYCLE TEST and return to thisstep. If continuous code 29 is displayed, replace ECA then repeat step1). If continuous code 29 is not displayed, replace original VSS thenrepeat QUICK TEST. 5) Continuous Code 69 Displayed. Perform AXOD DRIVE CYCLETEST and return to this step. If continuous code 69 is not displayed,fault cannot be duplicated at this time. If any other codes arepresent, return to QUICK TEST for instructions. If none, test iscomplete. If continuous code 69 is displayed, go to next step. 6) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECA and AXODharness disconnected. Set DVOM on 200-ohm scale. Measure resistancebetween test pin No. 19 and THS 3/2 circuit at AXOD harness connector.If reading is more than 5 ohms, repair open in THS 3/2 circuit thenrepeat step 5). If reading is 5 ohms or less, go to next step. 7) With key off, breakout box installed, and ECA and AXODharness disconnected, set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 19 and test pin No. 37. If reading isless than 10,000 ohms, repair short to power in THS 3/2 circuit, thenrepeat step 5). If reading is more than 10,000 ohms, go to next step. 8) With key off and breakout box installed, connect ECA andAXOD harness. Install a jumper wire between test pins No. 19 and 40.Perform KOEO SELF-TEST. If code 62 is displayed, remove jumper wireand go to AXOD TRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. If code 62 isnot displayed, remove jumper wire, replace ECA. Repeat step 5). 9) Continuous Code 59 Displayed. Perform AXOD DRIVE CYCLETEST and return to this step. If continuous code 59 is not displayed,fault cannot be duplicated at this time. If any other codes arepresent, return to QUICK TEST for instructions. If none, test iscomplete. If continuous code 59 is displayed, go to next step. 10) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECA and AXODharness disconnected. Set DVOM on 200-ohm scale. Measure resistancebetween test pin No. 18 and THS 4/3 circuit at AXOD harness connector.If reading is more than 5 ohms, repair open in THS 4/3 harness, thenrepeat step 9). If reading is 5 ohms or less, go to next step. 11) With key off, breakout box installed, and ECA and AXODharness disconnected, set DVOM on 200,000-ohm scale. Measureresistance between pin No. 18 and test pin No. 37. If reading is lessthan 10,000 ohms, repair short to power in THS 4/3 circuit, thenrepeat step 9). If reading is higher than 10,000 ohms, go to nextstep. 12) With key off and breakout box installed, connect ECA andAXOD harness. Install a jumper wire between test pins No. 18 and 40.Perform KOEO SELF-TEST. If code 62 is displayed, remove jumper wireand go to AXOD TRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. If code 62 isnot displayed, remove jumper wire, replace ECA, and then repeat step9). 13) Continuous Code 39 Displayed. Perform AXOD DRIVE CYCLETEST then return to this step. If continuous code 59 is also present,go directly to step 9). If continuous code 39 is displayed, go to AXODTRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. If continuous code 39 is notdisplayed, fault cannot be duplicated at this time. If any other codes

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are present, return to QUICK TEST for instructions. If none, test iscompleted. 14) Continuous Code 57 Displayed. Perform AXOD DRIVE CYCLETEST and then return to this step. If continuous code 57 is notdisplayed, fault cannot be duplicated at this time. If any other codesare present, return to QUICK TEST for instructions. If none, test iscompleted. If continuous code 57 is displayed, go to next step. 15) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECA and AXODharness disconnected. Set DVOM on 200-ohm scale. Measure resistancebetween test pin No. 30 and NPS circuit at AXOD harness connector. Ifreading is more than 5 ohms, repair open in NPS circuit, then repeatstep 14). If reading is 5 ohms or less, go to AXOD TRANSAXLEELECTRICAL SYSTEM DIAGNOSIS. 16) Code 89 Displayed. Turn key off and wait 10 seconds.Disconnect ECA 60-pin connector. Inspect connector for damaged pins,corrosion, or loose wires. Repair if necessary. Install breakout box,leaving ECA and AXOD harness disconnected. Set DVOM on 200-ohm scale.Measure resistance between test pin No. 37 and VPWR circuit at AXODharness connector. If reading is more than 5 ohms, repair open in VPWRcircuit then repeat QUICK TEST. If reading is 5 ohms or less, go tonext step. 17) With key off, breakout box installed, and ECA and AXODharness disconnected, set DVOM on 200-ohm scale. Measure resistancebetween test pin No. 53 and LUS circuit at AXOD harness connector. Ifreading is more than 5 ohms, repair open in LUS circuit and thenrepeat QUICK TEST. If reading is 5 ohms or less, go to next step. 18) With key off, breakout box installed, and ECA and AXODharness disconnected, set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 53 and test pins No. 37 and 40. Ifboth readings are less than 10,000 ohms, repair shorts in LUS harness.Repeat QUICK TEST. If code 89 is still displayed, replace ECA andrepeat QUICK TEST. If both readings are higher than 10,000 ohms, go tonext step. 19) With key off, breakout box installed, and ECAdisconnected, connect AXOD harness. Set DVOM on 200,000-ohm scale.Measure resistance between test pin No. 53 and test pin No. 57. Ifresistance is between 20 and 40 ohms, replace ECA and repeat QUICKTEST. If resistance is not between 20 and 40 ohms, go to AXODTRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. 20) Code 62 Displayed. Perform KOER SELF-TEST and recordcodes. If code 62 is displayed, fault is in THS 4/3 circuit. Go tonext step. If code 62 is not displayed, fault is in THS 3/2 circuit.Go to next step. 21) Turn key off and disconnect AXOD harness. Perform KOEOSELF-TEST. If code 62 is not displayed, go to AXOD TRANSAXLEELECTRICAL SYSTEM DIAGNOSIS. If code 62 is displayed, go to next step. 22) Turn key off and install breakout box. Leave ECA and AXODharnesses disconnected. Set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 18 and test pins No. 40 and 60. Alsomeasure resistance between test pin No. 19 and test pins No. 40 and60. If all readings are less than 10,000 ohms, repair short(s) toground. Repeat QUICK TEST. If all readings are higher than 10,000ohms, replace ECA and repeat QUICK TEST. 23) Verify that code 62 is present in KOER SELF-TEST. If code62 is displayed, go to AXOD TRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. Ifcode is not displayed, fault cannot be duplicated at this time. If anyother codes are present, return to QUICK TEST for instructions. Ifnone, test is completed. 24) Code 67 Displayed. Turn key on, leaving engine off.Disconnect ECA 60-pin connector. Inspect connector for damaged pins,corrosion, or loose wires. Repair if necessary. Install breakout box

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and connect ECA to box. Set DVOM on 20-volt scale. Measure voltagebetween test pins No. 30 and 46. If reading is more than 4.0 volts, goto CIRCUIT TEST O, step 4). If reading is less than 4.0 volts, go tonext step. 25) With key off, breakout box installed, and ECA and AXODharness disconnected, set DVOM on 200,000-ohm scale. Measureresistance between test pin No. 30 and test pins No. 40 and 60. If allreadings are less than 10,000 ohms, repair short to ground in NPScircuit. Repeat QUICK TEST. If all readings are higher than 10,000ohms, go to next step. 26) With key off and breakout box installed, connect ECA.Leave AXOD harness disconnected. Perform KOEO SELF-TEST. If code 67 isdisplayed, replace ECA and repeat QUICK TEST. If code 67 is notdisplayed, go to AXOD TRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. 27) Turn key off and wait 10 seconds. Locate and disconnectVehicle Speed Sensor (VSS). Set DVOM on 2000-ohm scale and measureresistance across vehicle speed sensor. If reading is between 190 and230 ohms, go to next step. If not, replace vehicle speed sensor andverify that complaint was eliminated. 28) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. Repair if necessary. Install breakout box, leaving ECAdisconnected. Set DVOM on 200-ohm scale. Measure resistance betweentest pin No. 3 and VSS harness connector. Also measure resistancebetween test pin No. 6 and VSS harness connector. If both readings are5 ohms or less, go to next step. If not, repair open circuit in VSSwiring harness. 29) Turn key off. With ECA and Vehicle Speed Sensor (VSS)disconnected, set DVOM on 200,000-ohm scale. Measure resistancebetween test pin No. 3 and test pins No. 37, 40 and 6. Also measureresistance between test pin No. 6 and test pins No. 37, and 40. If allreadings are greater than 10,000 ohms, go to next step. If not, repairshort(s) in VSS wiring harness. 30) Substitute VSS with known good sensor. Connect ECA andVSS. Test drive vehicle to verify complaint. If complaint iseliminated, replace VSS. If complaint is not eliminated, replace ECA.

Fig. 38: AXOD Transaxle Circuits

TEST TT - ERRATIC IGNITION

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1) Code 14 Displayed. This code indicates that 2 successiveerratic Profile Ignition Pick-Up (PIP) pulses were sent to ECA,causing possible engine miss or stall. Check EEC and TFI ignitionsystem for loose wires and connections, arcing secondary ignitioncomponents (coil, cap, wires, etc.), or an on-board 2-way radio. Makesure radio antenna and power leads are routed properly. If any of theabove conditions are present, repair as necessary and repeat QUICKTEST. If none are present, go to next step. 2) Turn key off and wait 10 seconds. Deactivate SELF-TEST.Using CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostictester for indication of fault while lightly tapping on TFI ignitionmodule and distributor, and while wiggling TFI harness connector. Iffault is indicated, disconnect and inspect connectors and terminals.If connectors and terminals are okay, diagnose TFI ignition system. Ifno fault is indicated, go to next step. 3) While in CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM ordiagnostic tester for indication of fault while wiggling, shaking, orbending small sections of harness from TFI module to firewall. Alsocheck harness from firewall to ECA. Isolate PIP circuit, if possible.If fault is indicated, isolate and repair problem and repeat QUICKTEST. If no fault is indicated, go to next step. 4) Turn key off and wait 10 seconds. Disconnect ECA 60-pinconnector. Inspect connector for damaged pins, corrosion, or loosewires. If connectors and terminals are okay, fault cannot beduplicated at this time. Diagnose TFI ignition system. If connectorsand terminals are damaged, repair as necessary and repeat QUICK TEST.

Fig. 39: TFI Ignition Circuit

AXOD TRANSAXLE

ELECTRICAL SYSTEM DIAGNOSIS

This test should be performed ONLY if a problem has beendetected in transaxle. If any of these service codes appeared duringSELF-TESTS, the AXOD DRIVE CYCLE TEST should be performed. Thefollowing AXOD transaxle related items have malfunctioned or failed asindicated:

* Code 39 Displayed. Transaxle converter by-pass clutch is not

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operating properly. * Code 59 Displayed. THS 4/3 pressure switch circuit has failed open. * Code 62 Displayed. THS 4/3 pressure switch circuit failed closed. If code appears in KEY ON/ENGINE OFF (KOEO) SELF- TEST, THS 3/2 circuit has failed. If code appears in KEY ON/ENGINE RUNNING (KOER) SELF-TEST, THS 4/3 circuit has failed. If code appears in both SELF-TESTS, both circuits have failed and must be checked. * Code 69 Displayed. THS 3/2 circuit has failed open. * Code 89 Displayed. Transaxle converter by-pass clutch solenoid has stayed always open or closed.

The following service codes are not AXOD transaxle related,but can affect converter clutch by-pass operation. Service thesecomponents before servicing AXOD transaxle codes:

* Code 21 Displayed. Engine Coolant Temperature (ECT) sensor out of range. * Code 22 Displayed. Manifold Absolute Pressure (MAP) sensor out of range. * Code 23 Displayed. Throttle Position Sensor (TPS) out of range. * Code 24 Displayed. Air Charge Temperature (ACT) sensor out of range. * Code 29 Displayed. Vehicle Speed Sensor (VSS) not functioning. * Code 74 Displayed. Brake ON/OFF (BOO) switch always open or brake not applied during KEY ON/ENGINE RUNNING (KOER) SELF -TEST. * Code 75 Displayed. Brake ON/OFF (BOO) switch always closed.

The following service code indicates that a transaxlecomponent may have caused faulty engine idle speed control:

* Code 57 Displayed. Neutral Pressure Switch (NPS) failed in Neutral (open). The NPS is normally open and closes with hydraulic pressure. Failure of transaxle to engage in "D" or "R" will cause service code 57 to be displayed. Check for proper hydraulic pressure before testing AXOD transaxle electrical components.

NOTE: Ensure that all components are connected before performing test. Perform AXOD DRIVE CYCLE TEST on a slight upgrade or flat terrain. If any other non-AXOD related codes appear, service those codes first as they could affect electrical operation of transaxle.

AXOD Drive Cycle Test. Record and zero service codes. Warmengine to normal operating temperature. With transaxle in "D" range,lightly accelerate from a stop to 40 MPH to allow transaxle to shiftinto 3rd gear. Hold speed and throttle opening steady for a minimum of15 seconds (30 seconds above 4000 feet altitude). Shift transaxle into overdrive and accelerate lightly from 40to 50 MPH to allow transaxle to shift into 4th gear. Hold speed andthrottle opening for a minimum of 15 seconds. With transaxle in 4th gear, throttle open and a steady speed,lightly apply and release brakes (enough to light brake lamps). Holdspeed and throttle opening steady for a minimum of 15 seconds. Brake to a stop and remain stopped for a minimum of 20seconds with transaxle in overdrive. Perform QUICK TEST and recordservice codes. 1) Code 39 Displayed. Check that vehicle harness connector is

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fully attached to transaxle bulkhead connector and that vehicleharness connector terminals are fully seated in connector. Ifconnector or terminals are not okay, repair as required and repeatQUICK TEST. If connector and terminals are okay, go to next step. 2) Install service jumper harness to transaxle bulkheadconnector. Connect VOM positive test lead to Red wire and negativetest lead to Black wire. Check resistance. If reading is between 20and 40 ohms, go to QUICK TEST and service codes as required. Ifreading is not between 20 and 40 ohms, go to next step. 3) Connect service jumper harness Red wire to batterypositive post. With engine running and transaxle in 3rd gear, connectservice jumper harness Black wire to ground (to energize by-passclutch solenoid). DO NOT connect with polarity reversed, otherwisesolenoid diode will be damaged. 4) If by-pass clutch is applied (engine RPM drops), there isno electrical component failure. By-pass clutch is operating properly.Error code may be indicating a slipping by-pass clutch. Servicetransaxle for a no converter clutch apply condition and repeat QUICKTEST. 5) If by-pass clutch is not applied (engine RPM does notdrop), check main control by-pass clutch control valve (in valve body)for sticking. If valve is sticking, service valve as required. Ifvalve is okay, go to next step. 6) Remove by-pass solenoid. Check condition of "O" ring. Alsocheck for contamination in/on solenoid or small hole in valve. Shakesolenoid vigorously to check for free armature. If solenoid is notokay, replace by-pass clutch solenoid and repeat QUICK TEST. Ifsolenoid is okay, service transaxle for a no converter clutch applycondition and repeat QUICK TEST.

NOTE: The THS 4/3 and 3/2 pressure switches are normally open and close with hydraulic pressure. Failure of transaxle to engage in "D" will cause code 59 to be displayed. Failure of transaxle to shift into 3rd gear will cause code 69 to be displayed. Check for proper hydraulic operation before testing electrical components.

7) Code 59 Displayed. Check that vehicle harness connector isfully attached to transaxle bulkhead connector and that vehicleharness connector terminals are fully seated in connector. Ifconnector or terminals are not okay, repair as required and repeatQUICK TEST. If connector and terminals are okay, go to next step. 8) Install service jumper harness to transaxle bulkheadconnector. Using VOM, check for continuity between engine ground andBlue wire. With engine running and transaxle in Neutral, VOM shouldindicate no continuity (infinite resistance). 9) Shift transaxle into "D". Switch should close andresistance should be less than 10 ohms. Switch should stay closed in1st, 2nd and 3rd gears, and then open in 4th gear. If circuit is okay,go to QUICK TEST and service codes as required. If circuit is notokay, go to next step. 10) Remove transaxle side oil pan. Check that internalconnector with Blue wire is firmly attached to THS 4/3 pressureswitch. Connector should not pull off easily or fit loosely. Ifconnector is not okay, replace bulkhead connector and wiring assembly.Repeat QUICK TEST. If connector is okay, go to next step. 11) Remove connector from pressure switch by pushing on endof connector, and while pulling on connector wire. Check forcontinuity in bulkhead connector by measuring resistance between Bluewire and terminal inside connector just removed. If reading is morethan 2 ohms, replace bulkhead connector and wiring assembly. RepeatQUICK TEST. If reading is less than 2 ohms, go to next step. 12) Remove THS 4/3 pressure switch. Install a 1/8-27 pipe

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fitting that can be connected to LOW pressure air supply in order topressure leak and test switch closure. With 50 psi (3.5 kg/cm

)applied, check for ruptured diaphragm by submerging switch in cleantransmission fluid. Check for bubbles coming out of small vent holenear switch terminal. If bubbles show, diaphragm has failed. ReplaceTHS 4/3 pressure switch and repeat QUICK TEST. If no bubbles show, goto next step. 13) With 50 psi (3.5 kg/cm

) applied to switch, checkresistance between switch terminal and switch case. If reading is lessthan 8 ohms, hydraulic pressure circuit to switch may have excessiveleaks. Service transaxle as required. If reading is more than 8 ohms,replace switch. Repeat step 8), and then QUICK TEST. Codes 39, 59, 62,69 and 89 should no longer be displayed.

NOTE: If code 62 appears in KEY ON/ENGINE OFF SELF-TEST, THS 3/2 circuit has failed. If code 62 appears in KEY ON/ENGINE RUNNING (KOER) SELF-TEST, THS 4/3 circuit has failed. If code 62 appears in both SELF-TESTS, follow entire test procedure to determine which circuit has failed.

14) Code 62 Displayed. Remove vehicle harness connector fromtransaxle bulkhead connector and install service jumper harness. UsingVOM, measure continuity between engine ground and White wire (THS 3/2circuit). With engine off, VOM should indicate no continuity (infiniteresistance). 15) Measure continuity between engine ground and Blue wire(THS 4/3 circuit). With engine running and transaxle in Neutral, VOMshould indicate no continuity (infinite resistance). If all readingsshow no continuity, go to QUICK TEST and service codes as required. Ifany reading indicates continuity, go to next step. 16) Remove transaxle side oil pan. Check for pinched, cut, orotherwise grounded wiring. If wiring is damaged, replace bulkheadconnector and wiring assembly. After repairs, repeat QUICK TEST. IfTHS 4/3 pressure switch wiring is okay, go to step 18). If THS 3/2pressure switch wiring is okay, go to next step. 17) Remove wiring from THS 3/2 pressure switch. Using VOM,check pressure switch for continuity to engine ground by connectingone lead to switch terminal and other lead to valve body. If there isno continuity (infinite resistance), go to step 19). If there iscontinuity to ground, replace THS 3/2 pressure switch and repeat QUICKTEST. 18) Remove wiring from THS 4/3 pressure switch. Using VOM,check pressure switch for continuity to engine ground by connectingone lead to switch terminal and other lead to valve body. If there iscontinuity to ground, replace 4/3 pressure switch and repeat QUICKTEST. If there is no continuity (infinite resistance), go to nextstep. 19) Using VOM and with wiring removed from both pressureswitches, check for continuity to ground. Connect one test lead toWhite wire and other test lead to ground. Then connect one test leadto Blue wire and other test lead to ground. Make sure that internalterminals are not touching any metallic parts. If there is continuityto ground, replace bulkhead connector and wiring assembly. RepeatQUICK TEST. If there is no continuity (infinite resistance), go toQUICK TEST and service codes as required.

NOTE: The THS 4/3 and 3/2 pressure switches are normally open and close with hydraulic pressure. Failure of transaxle to engage in "D" will cause service code 59 to be displayed. Failure of transaxle to shift into 3rd gear will cause code 69 to be displayed. Check for proper hydraulic operation before testing electrical components.

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20) Code 69 Displayed. Check that vehicle harness connectoris fully attached to transaxle bulkhead connector and that terminalsare fully seated in connector. If connector or terminals are not okay,repair as required and repeat QUICK TEST. If connector and terminalsare okay, go to next step. 21) Install service jumper harness to transaxle bulkheadconnector. Using VOM, check for continuity between engine ground andWhite wire. With engine running and transaxle in Drive, 1st, or 2ndgear, VOM should indicate no continuity (infinite resistance). 22) When transaxle shifts into 3rd or 4th gear, the switchshould close. Resistance should be less than 10 ohms between Whitewire and engine ground. If circuit is okay, go to QUICK TEST andservice codes as required. If circuit is not okay, go to next step. 23) Remove transaxle side oil pan. Check that internalconnector with White wire is firmly attached to THS 3/2 pressureswitch. Connector should not pull off easily or fit loosely. Ifconnector is not okay, replace bulkhead connector and wiring assembly.Repeat QUICK TEST. If connector is okay, go to next step. 24) Check for continuity in bulkhead connector by measuringresistance between White wire and terminal inside connector justremoved. If reading is more than 2 ohms, replace bulkhead connectorand wiring assembly. Repeat QUICK TEST. If reading is less than 2ohms, go to next step. 25) Remove THS 3/2 pressure switch. Install a 1/8-27 pipefitting that can be connected to LOW pressure air supply in order topressure leak and test switch closure. With 50 psi (3.5 kg/cm

)applied, check for ruptured diaphragm by submerging switch in cleantransmission fluid. Check for bubbles coming out of small vent holenear switch terminal. If bubbles show, diaphragm has failed. ReplaceTHS 3/2 pressure switch and repeat QUICK TEST. If no bubbles show, goto next step. 26) With 50 psi (3.5 kg/cm

) applied to switch, checkresistance between switch terminal and switch case. If reading is lessthan 8 ohms, hydraulic pressure circuit to switch may have excessiveleaks. Service transaxle as required. If reading is more than 8 ohms,replace switch. Repeat steps 21) and 22), and then repeat QUICK TEST.Codes 39, 59, 62, 69 and 89 should no longer be displayed. 27) Code 89 Displayed. If code 39 is also displayed, go tostep 1). Check that vehicle harness connector is fully attached totransaxle bulkhead connector and that vehicle harness terminals arefully seated in connector. If connector or terminals are not okay,repair as required and repeat QUICK TEST. If connector and terminalsare okay, go to next step. 28) Install service jumper harness to transaxle bulkheadconnector. Connect VOM positive test lead to Red wire and negativetest lead to Black wire. Check resistance. If reading is between 20and 40 ohms, go to QUICK TEST and service codes as required. Ifreading is not between 20 and 40 ohms, go to next step. 29) Remove transaxle side oil pan. Check that internalconnector is fully attached to solenoid. If connector is okay, go tonext step. If connector is not okay, fully engage connector and checkcontinuity once more. If resistance is still not between 20 and 40ohms, go to next step. If resistance is now okay, repeat QUICK TEST. 30) Remove connector from solenoid by pulling on wires at 2-way connector. Check solenoid continuity by connecting VOM positivetest lead to solenoid positive terminal and negative test lead tosolenoid negative terminal (polarity symbols are stamped on solenoidframe). 31) If circuit is open (infinite resistance), replacesolenoid and then repeat QUICK TEST. If solenoid is okay (20 to 40ohms resistance), replace bulkhead connector and wiring assembly.Connect all internal connectors and repeat step 28). If circuit testsokay, install oil pan. Repeat KEY ON/ENGINE OFF SELF-TEST. Code 89

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should no longer be displayed.

NOTE: The NPS is normally open and closes with hydraulic pressure. Failure of transaxle to engage in "D" or "R" will cause service code 57 to be displayed. Check for proper hydraulic pressure before testing electrical components.

32) Code 57 Displayed. Check that vehicle harness connectoris fully attached to transaxle connector and that vehicle harnessterminals are fully seated in connector. If connector or terminals arenot okay, repair as required and repeat QUICK TEST. If connector andterminals are okay, go to next step. 33) Install service jumper harness to transaxle bulkheadconnector. Using VOM, check continuity between Green wire and engineground. With engine running and transaxle in "P" or "N", VOM shouldindicate no continuity (infinite resistance). Shift transaxle into "R"and "D" ranges, switch should close. Resistance should be less than 10ohms in both ranges. If circuit is okay, go to QUICK TEST and servicecodes as required. If circuit is not okay, go to next step. 34) Remove transaxle side oil pan. Check that terminalconnector with Green wire is firmly attached to NPS. Connector shouldnot pull off easily or fit loosely. If connector is not okay, replacebulkhead connector and wiring assembly. Repeat QUICK TEST. Ifconnector is okay, go to next step. 35) Remove connector from NPS by pushing on end of connectorwhile pulling on connector wire. Check for continuity in bulkheadconnector by measuring resistance between Green wire and terminalinside connector just removed. If reading is more than 2 ohms, replacebulkhead connector and wiring assembly. Repeat QUICK TEST. If readingis less than 2 ohms, go to next step. 36) Remove NPS. Install a 1/8-27 pipe fitting that can beconnected to LOW pressure air supply in order to pressure leak andtest switch closure. With 50 psi (3.5 kg/cm

) applied, check forruptured diaphragm by submerging switch in clean transmission fluid.Check for bubbles coming out of small vent hole near switch terminal.If bubbles show, diaphragm has failed. Replace NPS and repeat QUICKTEST. If no bubbles show, go to next step. 37) With 50 psi (3.5 kg/cm

) applied to switch, checkresistance between switch terminal and switch case. If reading is 8ohms or less, hydraulic pressure circuit to switch may have excessiveleaks. Service transaxle as required. If reading is more than 8 ohms,replace switch. Repeat step 33), and then repeat QUICK TEST. Codes 39,59, 62, 69 and 89 should no longer be displayed.

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Fig. 40: AXOD Transaxle

DRIVEABILITY TESTS

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INTERMITTENT NO START, QUITS ON ROAD WITH NO RESTART

1) If engine does not start, do QUICK TEST diagnosticprocedure. 2) If engine starts, check for operating fuel pump whenignition is on, spark at coil, ignition system (wires, cap and rotor),Thick Film Integrated (TFI) ignition module and baseline key voltageswith breakout box.

INTERMITTENT SURGING AT STEADY SPEED

Check plug firing voltages, cylinder balance, base ignitiontiming, spark plug type and MAP. See MAP VOLTAGE SPECIFICATIONS table.Check flow of fuel injectors and fuel pressure.

MAP VOLTAGE SPECIFICATIONS TABLE�����������������������������������������������������������������������������������������

Elevation (Ft.) Voltage Output (Volts)

0 ............................ 1.55-1.631000 ............................ 1.52-1.602000 ............................ 1.49-1.573000 ............................ 1.46-1.544000 ............................ 1.43-1.515000 ............................ 1.40-1.486000 ............................ 1.37-1.457000 ............................ 1.35-1.43�����������������������������������������������������������������������������������������

INTERMITTENT QUITS ON ROAD & RESTARTS

Check baseline readings of key voltages while engine isoperating. Compare voltages with readings obtained when intermittentproblem occurs and perform QUICK TEST.

INTERMITTENT BUCKING & JERKING

1) Check ignition system secondary wires, distributor cap androtor, Thick Film Integrated (TFI) ignition module, engine spark, plugfiring voltages, cylinder balance, and base ignition timing. Checkspark plugs for fouling and proper gap. 2) Perform QUICK TEST. Connect Manifold Absolute Pressure/Barometric Pressure (MAP/BP) tester to MAP sensor. Check readingswith engine off and with ignition switch in "ON" position. Comparereading with MAP VOLTAGE SPECIFICATIONS table. 3) Check for loose air tubes, missing hoses, or vacuum plugs.

MAP VOLTAGE SPECIFICATIONS TABLE�����������������������������������������������������������������������������������������

Elevation (Ft.) Voltage Output (Volts)

0 ............................ 1.55-1.631000 ............................ 1.52-1.602000 ............................ 1.49-1.573000 ............................ 1.46-1.544000 ............................ 1.43-1.515000 ............................ 1.40-1.486000 ............................ 1.37-1.457000 ............................ 1.35-1.43�����������������������������������������������������������������������������������������

INTERMITTENT ERRATIC RUNNING OR ROUGH IDLE

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1) Check color at top of fuel injectors to ensure correctapplication. Check distributor cap, plug firing voltages, cylinderbalance, and base ignition timing. 2) Check spark plugs for fouling and proper gap, cylindercompression, and engine/valve train operation. Check Thick FilmIntegrated (TFI) ignition module, Profile Ignition Pick-Up (PIP), andcoil. 3) Check Spark Output (SPOUT) connector. Connect ManifoldAbsolute Pressure/Barometric Pressure (MAP/BP) tester to MAP sensor.Check readings with engine off and with ignition switch in "ON"position. Compare reading with MAP VOLTAGE SPECIFICATIONS table. 4) Repeat MAP test with engine running. Reading shoulddecrease at idle and increase when throttle is opened. If readingswith engine off and ignition on do not match values given, go toCIRCUIT TEST H, MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR test. 5) If MAP sensor does not change when throttle is opened(engine running), substitute a known good vacuum hose at sensor andrepeat test. On vehicles equipped with either MAP or BP sensors,substitute sensor(s) and retest. 6) On Vane Airflow Meter (VAF) equipped vehicles, check forunmetered air leaks. Using breakout box, monitor VAF signal whilemanually moving vane door. Voltage must smoothly increase as door isopened. Using Fuel Injector Tester/Cleaner (Rotunda 113-00001), checkflow of injectors.

MAP VOLTAGE SPECIFICATIONS TABLE�����������������������������������������������������������������������������������������

Elevation (Ft.) Voltage Output (Volts)

0 ............................ 1.55-1.631000 ............................ 1.52-1.602000 ............................ 1.49-1.573000 ............................ 1.46-1.544000 ............................ 1.43-1.515000 ............................ 1.40-1.486000 ............................ 1.37-1.457000 ............................ 1.35-1.43�����������������������������������������������������������������������������������������