Vehicle Electrical Actuators

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Vehicle Electrical Actuators

some types of Actuators

Actuators are a subdivision of transducers. They are devices which transform an input signal (mainly anelectrical signal) into motion. Like include electrical motors, pneumatic actuators, hydraulic pistons, relays,piezoelectric actuators, thermal bimorphs, and electro active polymers.

Vehicle Common Actuators

Fuel PumpFuel Pump is powerd from the Vehicle battry and connected to the engine ECU , to give the engine

the fuel at the right pressure suitable for its work

InjectorsInjector is an injection nozzle with solenoid that is controlled by ECM. Using intake air quantity and

engine rpm, ECM calculates basic fuel injection time, and calculates corrective fuel injection period

time on the basis of engine coolant temp, feed back signal from oxygen sensor during close-loop-

control,
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Fuel pressure RegulatorInjection rate through injector depends on injection pressure, injection time and orifice size.

Therefore in order to control fuel injection rate by means of current connecting time for an injector

with spray hole size fixed, injection pressure shall remain constant for any varied pressure at intake

manifold.

Idle Speed ActuatorISA (Idle Speed Actuator) is installed at throttle body of engine and control air intake rate into

engine depending on ECU signal in order to control idle rp Idling speed is controlled relying on a

number of parameters including actual engine rpm, coolant temperature, air-conditioning system

and headlamp operation status, etc.

Spark PlugsSpark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of

voltage must be supplied by the ignition system to cause it to spark across the gap of the spark

plug. This is called Electrical Performance.

Ignition CoilsThe Ignition coil functions as an energy-storage device and transformer. It is supplied with DC

voltage from the alternator, and provides the high tension ignition pulses for the spark plugs. The

MFI engine adopts a computerized ignition system. The ECM calculates ignition timing, timing

advance, and knocking control by the sensor signals.

Exhaust Gaz recirculation

Exhaust gas contains NOx that is hazardous to human central nervous system and mucous

membrane, as well as is globally principal cause for photochemical smog, and therefore globally

subject to increasingly strong regulation together with HC and CO. As CO and HC are resulting from

imperfect combustion, improved combustion will improve engine performance, too.

Purge Soleniod Valve ControlA vehicle generates evaporated gas at fuel system such as fuel tank, and HC is the main substance

of the gas. Fuel tank requires venting system to avoid pressure rising in the tank when raised

temperature generates volume expansion, and there after resulting vacuum pressure. In addition,

vapor gas control system is required to prevent fuel vapor from being discharged into atmosphere.

Variable Intake ControlVariable intake system varies length of intake manifold in order to improve engine output over all

engine operation range, and in particular increase engine output by approx. 10% at low-medium

speed range. For frequent crowded downtown driving, engine shall provide high power at low-
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medium speed range. Highway driving and high speed running requires engine with high power at

high speed range.

Cooling Fan ControlIn order to maximize cooling efficiency and minimize cooling fan motor drive current, radiator fan

and condenser fan speeds are controlled using three speed modes such as low, medium, and high

speed, on the basis of coolant temperature, car speed, air conditioning switch signal, and

conditioning compressor operation signal.

Generator Current ControlWhen turning on headlamp or heating wire in idling, engine rpm will instantly fall down and then

recovered due to increased generator load. At that time increasing electrical load will generate rapid

engine rpm change, resulting to vibration and poor comfortableness. Generator current control

system depends on engine ECU

A/C compressor controlA/C Compressor Control Outline A/C Compressor Control is used when accelerating or engine load is

instantly increased greatly, in order to improve engine acceleration by temporarily turning off A/C

compressor.

Control Relay ControlControl relay consists of main relay that provides supply power to engine ECU and various actuators

and fuel pump relay that drives fuel pump. Main relay control will operate as soon as ignition switch

turns on.

Vehicle Fuel Pump
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Fuel Pump types

Fuel systems types


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1. Fuel Pump Outline

Upon starting, fuel pump is driven by battery power and controlled by ECM, thereafter. Tube types of fuelpumps are used: Pumps of in-tank type are installed in fuel tank and pumps of in-line type are installedoutside fuel tank. In-line type pumps are generally preferred and used due to their superior anti-noise andanti-vapor-lock characteristics. The pump consists of a DC motor, a check valve, and a relief valve, and hasrelatively high current that is controlled by control relay, etc.In accordance with installation methods, the pumps are divided into:

External fuel pump. In-tank fuel pump.

2. External Fuel Pump

An external fuel pump is a fuel pump installed in line outside fuel tank that sucks fuel by means ofcentrifugal force generated by the rotating rotor of a ferrite-type motor, and provides the fuel to fuel supplyline. Fuel pump consists of rotor plate that is driven by motor, pump casing eccentrically located againstrotor plate, and roller that seals pump spacer between pump casing and rotor plate.Operation of fuel pump relies on the centrifugal force generated by rotor, that will push outer wall of pumpspacer moving along the wall, in order to generate vacuum space between rollers and pump spacer at inletside, and then the vacuum space will be filled with fuel. Rotation of the Roller will increase the space and

deliver the fuel to outlet side. Then the space will be decrease at outlet side increasing pressure todischarge the fuel. Discharged fuel from the pump will then pass around the armature of the motor to opencheck valve and there after pass through silencer to reach fuel line. Suction/discharge will be completed byone revolution of rotor during pump operation.Fuel pump has operation speed of 1,700-2,500 rpm, and discharge rate of about 1.5-2.5 l/min and pressureof 3.0~6.0.Fuel line has supply pressure of 2.75-3.40 regulated by fuel pressure regulator and includes silencer atoutlet side to prevent pulsation of pump.1) Relief Valve (Pressure Limiter)When fuel supply line is clogged during the pump operation, relief valve will ensure safety and avoid risk ofdamaging fuel supply system and fuel leak. The valve will open, if fuel pressure reaches specified value, inorder to route the high pressure to the inlet side of the pump and then through the inside of pump andmotor for preventing cumulative pressure.2) Check Valve (Non-Return Valve)

Upon stopping engine, check valve located in fuel pump will close using spring force, and maintain pressureinside fuel line to ensure easier re-start of engine, and to prevent possible vapor lock by high temperaturein fuel system.3) SilencerSilencer decreases the pressure change (pulsation) and noise generated by fuel flow from fuel pump,relying on diaphragm and orifice.3. in-tank Fuel Pump

Most of in-tank fuel pumps are from impeller type. The pump is installed in fuel tank, and therefore superiorto external fuel pumps in the following characteristics:

low operation noise and to less discharge pulsation of fuel.

low torque and high revolution type motor enables compact and light design. Have great characteristics to prevent fuel leak and vapor Lock.

Fuel pump consists of DC motor part and turbine pump, which is integrated using motor driven impeller andpump chamber that includes pump casing, pump cover, relief valve and check valve. When the rotationforce is delivered to impeller, pressure gap will be generated by friction between grooves around impellerand fluid. Motor operation will continue to repeat the operation, and then fuel fluid that will generate spiralflow will pass through motor raising pressure. Then the raised pressure will open check valve delivering fuel


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to outlet. Fuel pump has speed of 1,700~2,500 rpm, discharge pressure of approx. 3.0~6.0. Fuel linepressure ranges between 2.75~3.45 kg/cm2.1) Relief ValveFuel pump operates by DC motor at constant speed, and therefore generates constant pressure ofdischarged fuel, irrespective to engine speed. The discharge pressure, however is set based on high-speedoperation of engine, and then will rise too high when engine operates at low speed and consumes less oil.The abnormally high pressure will then open relief valve, in order to lower the pressure and maintainconstant fuel pressure in fuel line that will otherwise go up abnormally higher than specified pressure value.2) Check Valve

As soon as fuel pump stops check valve spring will automatically close outlet, in order to maintain fuelpressure in fuel line, and consequently prevent otherwise possible vapor lock in fuel line by hightemperature during summer-time or after stopping engine, and ensure easier start-up of engine next time.In addition the valve prevents reverse flow of fuel due to excessive pressure in fuel line upon engine start-

up4. Operation Checking of Fuel Pump

1) Turn off ignition switch.2) Directly connect battery power to fuel pump drive connectors. Listen to the pump operation noise. As thepump is located inside fuel tank, you may be hard to hear the noise. Then open fuel tank cap and listen tothe noise through filler port.3) Install a pressure gauge at service valve or fitting surface of pressure gauge, and watch, rising fuelpressure. (See below for more details)4) Use an ammeter and measure current consumption of fuel pump.

5) Hold fuel hose with hand check to feel the fuel pressure.As for the fuel pump operation voltage, measure the voltage at the fuel pump check terminal in the enginecranking or engine running condition.In this case, measured voltage should be the same as the battery voltage. If not, check the fuse, fuel pumprelay, ECM and wiring condition of the fuel pump check terminal.The ECM operates fuel pump when crankshaft position sensor transmits the signal. If the fuel pump,injector and ignition spark do not operate while cranking, check the crankshaft position sensor. As for thecrankshaft position sensor check, please refer to the engine sensors section.As for the fuel pressure check, measures the fuel pressure at the fuel line to check whether it meetsspecification or not. Please refer to the shop manual, because measurement location and fuel pressurevaries with difference models.

5. Fuel Pressure Test

1) Fuel Pressure RegulatorFuel amount injected by an electronically controlled engine relies on fuel pressure and length of fuel

injection time. Therefore the fuel quantity is controlled by length of fuel injection time under constant fuelinjection pressure. Then pressure gap between fuel pressure and inside of intake manifold shall be constantin order to control fuel injection rate by the time of fuel injection of injector. For this purpose, fuel pressureregulator is installed in fuel delivery pipe (In case of returnless fuel system it is located with fuel pumpinside of fuel tank). Fuel pressure regulator has spring seal, which is connected to intake manifold viavacuum hose effecting pressure variation in intake pipe in order to maintain the injection pressureconstantly.Fuel pump maintains fuel pressure approximately constant for right injection. Two types of fuel pump areavailable:

Return type system returns surplus fuel except for supplying into engine. Returnless type system supplies fuel just as much as used for engine.

Fuel pressure is decided so as to enable enough quantity of fuel injected from injector and simultaneouslyfacilitate vaporization. In addition it is better to maintain the pressure as high as possible to restraingeneration of vaporized gas in fuel line system. However the pressure will be limited by the reliability of thesystem for extended operation at higher pressure, and reliability of power supply for maintaining highpressure for extended time of period.2) Returnless Fuel SystemThe advantage of Returnless type over return type is to constrain fuel temperature and vaporized gasgeneration as possible. When fuel is supplied to engine and returns, the fuel will be heated by engine andbecome hot, and therefore it is needed for fuel to supply only at quantity used for engine. Minimizing thefuel vapor is intended to respond to emission control regulation.


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Return type pumps deliver always constant quantity of fuel, and easy for pressure control.On the contrary Returnless type pumps would require a fuel pressure regulation mechanism. Pressure checkvalve is designed inside the pump to constrain the pressure at certain level when the pressure goes beyondthe level. Besides length of injector opening time is used of micro-adjustment of fuel supply.3) Fuel Pressure Test Procedure (Return Type Fuel System)In order to release residual fuel pressure in fuel pipe line and prevent fuel from flowing out:1) Disconnect fuel pump harness connector at fuel tank side.2) Start engine, and leave it idling until stops for itself, and then turn ignition off.3) Disconnect battery negative (-) terminal.

4) Connect fuel pump harness connector.

Disconnect high pressure fuel hose at delivery side.

Using a fuel pressure gauge adapter, install a fuel pressure gauge on fuel filter. Tighten it to thespecified value.(tightening torque for fuel pressure gauge and fuel filter: ( 2.5~3.5kgm).

Connect battery (-) terminal. Connect battery terminal/to drive terminal and operate fuel pump and then check matching face

with pressure gauge and special tools for leak.

Remove vacuum hose from pressure regulator, and close the end of the hose, and then measure

fuel pressure with engine idling. (Specified value for fuel pressure: ( 3.26~3.45 kg/cm2)

Connect vacuum hose to pressure regulator, and measure fuel pressure again. (specified valve forfuel pressure: approx. ( 2.75kg/cm2).

If the measurements are outside the specified values.

Stop engine and watch movement of the pointer of the pressure gauge. The pointer shall not move.If the pointer moves down, check the moving range.

6. Symptoms of Fuel Pump Failure

Stop the engine during idling.

In driving, acceleration is poor and bumpy or engine goes out.

Noise of fuel pump motor is high.


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Poor or non start-up of engine.

You can check the actuator actual value and status and activate it when it is possible by AutoHex

automotive Scanner under the supported car brand and according to engine type.

Injectors of the Vehicle

injection system and control


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(2) Conical Spray (Pintle Type Injector)Precisely machined conical shape at end of needle valve located at fuel outlet, can respond to differentspraying angles required by engine. In addition sharp outlet edge at tip of the cone ensures better fuelparticulate.(3) Conical Spray (Four-Hole Injector)A four-hole injector has advantages over a Pintle type injector in relation with fuel particulate and sprayingangle. Each thin spray will be formed by the four holes installed on orifice plate at specific angle againstaxial direction of the injector. Each spray will form specific spray angle and provide better particulate effect,used together with protective sleeve.

(4) Two-Spray InjectorEngines with two inlets per cylinder use this injector. The center lines of sprays shall orient toward intakevalves. Then the engine requires injectors that generate two separate sprays with different spraying angles.(5) Multi-Hole Injector

Fine holes at orifice plate enable to generate better particulate effect of sprayed fuel, and different angles ofholes prevent spray particles from confinement that may occur by reduced momentum of fuel spray.3) Checking of injectorInjector shall be checked for operation noise, the resistance of injector, fuel injection rate, fuel spraypattern (spray angle, rear trace, etc). However it is not easy to directly check fuel injecting rate or fuelspray pattern on an actual car.Check connectors for connected status, and wires for disconnection and short.Check if correct injectors are installed. Injector operation noise may be checked using a stethoscope ingeneral.If hot engine is hard to start up, and then check fuel pressure and injector leakage.

If engine cranking fails to operate injectors, check ECM power supply circuit and grounding circuit, controlrelay, crank angle sensor or No1 cylinder TDC sensor for defects.When shutting down fuel injection of injectors one by one during idling, if a cylinder is not proved to change

its idling status, check the cylinder for injector harness, ignition plugs high voltage cable, compressionpressure, etc.In addition if injector harness and each part are checked to be normal and how ever injector operation timeis outside the specified value, then check whether there are imperfect combustion in cylinder (defectiveignition plugs ignition coils, compression pressure, etc) and whether EGR valves operate normally.Let us look at the each checking methods one by one as for the resistance check, measure the resistancedirectly after removing the injector connector. Then, the inner coil condition of the injector can be checked.To check the injector operating sound, contact the stethoscope or driver to the injector while the engine isrunning. The operation sound of the plunger or needle valve can be checked.To check the injector operation with the test lamp, connect the end of the test lamp to the positive terminalof the battery, and connect the other end to the terminal at the ECM side of the injector. Then crank or idle

the engine to check whether the lamp blinks.Through this test, we can check whether the ECM controls the injector or there is any wiring trouble.

To check with the waveform, we can check the waveform at the ECM side wire. In injector waveform, thevoltage before and after injection operation should be equal to the battery voltage. If not, there should be aproblem in the power supply system from the battery positive terminal to the injector. Besides, voltageshould be close to 0 volt. If not, there should be problem with the ECM and wirings from injector to ECMground.4) Fuel injection Pattern AnalysisInjector drives are divided into pick and hold type injector and voltage drive type injector. In additioninjectors may be classified into low resistance injectors and high resistance injectors depending onresistance level of the injectors. Voltage drive injectors include low resistance injectors and high resistanceinjectors, and especially low resistance type has coil resistance of approx. 0.6~3 Ohms, and uses anexternal resistance together. It is intended to increase response and endurance of injectors, and achievedby decreasing number of winding times of solenoids.

By reducing number of windings of solenoid coils, current is increased and injectors have better operationcharacteristics. Then excessive current may flow through solenoids to damage coil or decrease endurance.Therefore an external resistance is used to avoid mentioned damages. High resistance injectors haveresistance of 12 ~17 Ohms to increase solenoid coil resistance for limiting current. This type of voltagedrive has simpler circuit configuration, but increase impedance, so that current at injector may be reducedto lower sucking force of injector, and resultantly provide relatively inferior dynamic range characteristics.Injectors have peak and hold circuit by ECM, and when injecting signal is on, current delivered to injectorwill change. At initial stage of injector operation, high current flows to increase magnetic force and decreaseinertia of solenoid to enable initial operation, and use low current after needle valve opens. Peak and holdtype has complicated circuit configuration, but has low circuit impedance for superior dynamic rangecharacteristics of injector.In addition Soho circuit in injector drive circuit protects power transistor from reverse-electromotive force


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generated at solenoid coil when injection signal is off, and eliminates arc in order to reduce valve close timeof injector.You can check the actuator actual value and status and activate it when it is possible by AutoHexautomotive Diagnostic Scanner under the supported car brand and according to engine type.

Injectors of the Vehicle Keywords:

Fuel Pressure Regulator


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Fuel Pressure Regulator Config

Fuel Pressure Regulator work

1) Function

Injection rate through injector depends on injection pressure, injection time and orifice size. Therefore inorder to control fuel injection rate by means of current connecting time for an injector with spray hole sizefixed, injection pressure shall remain constant for any varied pressure at intake manifold.Fuel injection rate required by engine is controlled by power supply time of the injector from ECM. At agiven power supply time as fuel pressure is not controlled, even if power time of the injector is the same, iffuel pressure is high fuel injection rate will be high and if the pressure is low the rate will be low.Injection occurs at intake manifold. At a given fuel pressure against atmospheric pressure, when absolute

pressure of the intake manifold is low, fuel injection rate will be high, and when the pressure is high therate will be low. Therefore fuel pressure regulator maintains fuel pressure always higher than intakemanifold pressure base of the injection pressure, by a certain level as pre-set, so as to enable to control

injection rate only by injector power supply time.Therefore fuel pressure regulator regulates injection pressure of the injector at a certain level againstnegative pressure of the intake manifold.2) Configuration and Operating Principle

Pressure regulator consists of outer metal housing, valve diaphragm and diaphragm chamber, and fuelchamber.

Diaphragm chamber is connected with surge tank via vacuum hose and therefore has negative pressurefrom intake manifold. When fuel pressure is over specified value, diaphragm will be raised by vacuum fromsurge tank, and surplus fuel will return through return pipe to fuel tank. For example, at diaphragmpressure is set at 3.35kg/cm2, when intake manifold negative pressure is 0 and fuel pressure is above


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3.35kg/cm2, the pressure will disable the spring tension and push diaphragm up to return surplus fuel tofuel tank.1) Auto Fuel Cut System

Auto fuel cut system is a safety device to prevent the fire when the vehicle is crashed. It cuts the electricalpower of the fuel pump if the sensor detects the crash.The sensor location is on the left hand side strut housing in the engine room.Operation range:Over 25 Km/hour

Front crash:Must be switched off 22 Km/hour - 14 Km/hour.Gray zone:under 12 Km/hour front crash: must not be switched offIf the vehicle is crashed, steel ball is moved up. The steel ball pushes the (moving contact), the switch isturned off.Service pointReset the sensor by pushing of reset switch when the sensor is replaced. Reset the sensor to start theengine after crash. Engine does not start if the sensor was not reset.Component inspection two terminals should be continued after reset.You can check the actuator actual value and status and activate it when it is possible by AutoHex autoDiagnostic Scanner under the supported car brand and according to engine type.

Fuel Pressure Regulator Keywords:

diagnostic scanner

Fuel Pressure Regulator Related pages:

Injectors Fuel Pump Fuel pressure Regulator Fuel Supply

Electronic Fuel Injection

Idle Speed Actuator
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Idle Speed Actuator Circuit


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Idle Speed Actuator Types

1. GeneralISA (Idle Speed Actuator) is installed at throttle body of engine and control air intake rate into enginedepending on ECU signal in order to control idle rpm. Idling speed is controlled relying on a number ofparameters including actual engine rpm, coolant temperature, air-conditioning system and headlampoperation status, etc. ECM transforms the information into ISA control signal for optimal idling control.2. Function

1) Optimal Fuel Consumption and Quietness in IdlingIn idling lowest engine rpm will be best in the sense of fuel mileage and noise and vibration. However,engine output is low at too low rpm, and then engine speed will be unstable when engine load increases,

and resultantly engine may generate vibration or stop. On the contrary high idling rpm will result to poormileage in idling and worse emission. Therefore idling speed shall be controlled in response to changingdrive conditions.


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2) Cranking Idle ControlAir intake rate is controlled depending on coolant temperature.3) Fast Idle ControlDecrease Warm-up time of Engine.4) Idle Up ControlIdling speed will be raised to preset target rpm relying on electrical load by, for example, air-conditioningsystem, and load status signal from Auto-transmission if provided.5) Dash Pot ControlThe function will prevent sudden closing of throttle valve, and consequently relieve engine shock and

improve emission control, during rapid deceleration.6) Limp Home FunctionUpon uncontrollable emergency condition, as wiring harness for power supply and control is disconnected,the function will ensure minimum air intake required for driving to a service center. The function is available

for rotary slide type configuration.3. System Configuration

1) By-pass Air Control TypeDepending on kinds of typically used actuators, it may be classified into Rotary solenoid type, linearsolenoid type, and Step motor type.

Rotary Solenoid TypeThe actuator consists of drive part including coil and permanent magnet, and flow control partincluding rotating type rotary valve. Rotary solenoid is a proportional electronic valve that regulates

air flow route area using different valve positions by turning valve on the basis of current level

flowing through coil. Using rotary type valve has advantage of stable control, not affected by

pressure gap between up-stream and down-stream of valve.

Each coil receives opposite signals from each other alternately. In other words, the closing coil turns

off when the opening coil is on. On the contrary, the closing coil turns on when the opening coil is

off.

The ECM carries out these on and off motion 100 times per second, which corresponds to 100 Hz.

The ECM also controls the on and off time, which varies depending on the engine condition.

This type control is called duty control, in which on and off ratio is controlled. Linear Solenoid Type

Linear solenoid type controls lower air rate, and therefore used with an air valve. This type moves

the valve position where electromagnetic force generated by magnitude of current flowing through

solenoid makes equilibrium with spring force, in order to regulate air flow route area this type valve

is a proportional electronic valve.

Step Motor TypeThe actuator consists of rotor made of permanent magnet, step motor made of stator coil, feed

screw that converts rotating motion to back-and-force motion, and valve part. Step motor converts

current in stator coil step-by-step and control in order to rotate rotor either in forward or reverse

direction. Then feed screw moves valve up-and-down to regulate air route area.

The Step motor type Idle Speed Actuator is installed on the throttle body, and controls the engine

speed by controlling the air flow bypassing air.

The Step motor has 6 terminals. Battery power is supplied to 2 terminals through the control relay.

The others are connected to the ECM and 4 coils are controlled sequentially. The motor rotates by

the on and off of the terminals in sequence. In reverse rotation, it is controlled in the reverse order.


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As for the motor rotation, 1 rotation consists of 24 steps, and 5 rotations can be made because it

has 120 steps.

2) Throttle Valve Direct Drive TypeThrottle valve direct drive type indicates controlling full close position of throttle valve. The actuatorcontrols against force of return spring applied at throttle valve closing direction generally. The actuator usesa step motor or a DC motor. As the actuator uses relatively high force, it has a disadvantage to make a bigbody of actuator.4. ISA Checking1) Checking of Idling Speed

Checking Items1. Coolant temperature : 85-95 C

2. Lamp, cooling fan, other accessories : off

3. Power steering wheel : Orient straight for ward

Checking Order1. Ensure that there is no trouble at MPI device before checking.

2. Check ignition timing. If it is outside specified value, check sensors that may affect ignitiontiming.

3. Connect tachometer to engine speed detection terminal.

4. Operate engine at 2,000~3,000rpm at least 5 seconds.

5. Idle engine for two minutes.

6. Read idling speed and compare it with specified value provided at the relevant service manual.

(Example specified value: 800 100rpm).

2) Adjusting Idling Speed

This type uses a Micro-computer to automatically control idling condition, and requires no external

adjustment. If idling condition is unstable, then therefore you are required to check spark plugs, ignition

timing and ignition coil, ISA, leak of intake air, fuel pressure, etc, and consequently decide the cause.3) ISA Checking

Terminal 1 is for open ISA signal, terminal 3 is for close ISA signal, and terminal 2 is for power supply. A

circuit tester is used to check connectivity between terminal 2 & 1 and between terminal 2 & 3. Then

terminal 2 & 3 will be disconnected with ignition switch off and connected with ignition switch on. In

addition measure voltage at terminal 2 and find if normal battery voltage is applied. When using

oscilloscope, read output waveform at terminal 1 or 3, and find duty rates for open signal and close rates.

Thereafter decide whether the read values are within in specified values.

The duty value of the idle speed actuator is displayed on the current data of the Hi-scan. ISA duty 30%

means that the ECM turns on the opening coil 30% to let the opening be 30%. Though it will not be

displayed in the current data, in case of the closing coil, the closing coil turns on 70% to let the closing be

70% because it is the reverse of the opening coil.

To check the resistance, remove the idle speed actuator connector and measure the resistance of theopening coil and closing coil directly. Through this, we can check the internal coil condition of the idle speed

actuator.

To check the waveform, measure the waveform at one of the ECM side wires

in the idle speed actuator waveform, voltage at the off state should be the same as the battery voltage. If

not, there should be a trouble in power supply system from battery positive terminal to the idle speed

actuator. Besides, voltage should be close to 0 volt.

If not, there should be trouble with the ECM or wirings from the idle speed actuator to ECM earth.

To check operation, remove the idle speed actuator from the engine, and operate the engine. Then check

for valve operation as given duty percentage and any noise while operating.

Through this, we can check the mechanical problem and noise of the idle speed actuator, the Next one is


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Spark Plug Types


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Spark Plug Instalation

1. Spark Plug Basic

The spark plug has two primary functions:(1)To ignite the air/fuel mixture.(2)To remove heat from the combustion chamber.Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltagemust be supplied by the ignition system to cause it to spark across the gap of the spark plug. This is called"Electrical Performance".The temperature of the firing end of the spark plug must be kept low enough to prevent pre-ignition, buthigh enough to prevent fouling. This is called "Thermal Performance", and is determined by the heat rangeselected.It is important to remember that spark plugs do not create heat, they can only emit heat. The spark plugworks as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, andtransferring the heat to the cooling system of the engine. The heat range is defined as the ability of a sparkplug to dissipate heat.The rate of heat transfer is determined by:(1) The insulator nose length.(2) Gas volume around the insulator nose.(3) The materials/construction of the center electrode and porcelain insulator.The heat range of a spark plug has no relationship to the actual voltage transferred though the spark plug.Rather, the heat range is a measure of the ability of the spark plug to remove heat from the combustionchamber. The heat range measurement is determined by several factors; the length of the ceramic centerinsulator nose and its ability to absorb and transfer combustion heat, the material composition of theinsulator and center electrode material.1) Heat rating and heat flow path of Spark PlugsThe insulator nose length is the distance from the firing tip of the insulator to the point where insulator


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meets the metal shell. Since the insulator tip is the hottest part of the spark plug, the tip temperature is aprimary factor in pre-ignition and fouling. Whether the spark plugs are fitted in a lawnmower, boat, or arace car, the spark plug tip temperature must remain between 500C~850 Degree C. If the tip temperatureis lower than 500 Degree C, the insulator area surrounding the center electrode will not be hot enough toburn off carbon and combustion chamber deposits. These accumulated deposits can result in spark plugfouling leading to misfire. If the tip temperature is higher than 850 Degree C the spark plug will overheatwhich may cause the ceramic around the center electrode to blister and the electrodes to melt. This maylead to pre-ignition/detonation and expensive engine damage. In identical spark plug types, the differencefrom one heat range to the next is the ability to remove approximately 70 Degree C to 100 Degree C from

the combustion chamber. A projected style spark plug firing tip temperature is increased by 10 Degree C to20 Degree C.2) Tip Temperature and Firing End AppearanceThe firing end appearance also depends on the spark plug tip temperature. There are three basic diagnostic

criteria for spark plugs: good, fouled and overheated. The borderline between the fouling and optimumoperating regions (500&def; C) is called the spark plug self-cleaning temperature. The temperature at thispoint is where the accumulated carbon and combustion deposits are burned off.Bearing in mind that the insulator nose length is a determining factor in the heat range of a spark plug, thelonger the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinderhead water journals. This means the plug has a higher internal temperature, and is said to be a hot plug. Ahot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, andhas no relationship to spark quality or intensity.Conversely, a cold spark plug has a shorter insulator nose and absorbs more combustion chamber heat.This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A

colder heat range is necessary when the engine is modified for performance, subjected to heavy loads, or isrun at high rpm for a significant period of time. The colder type removes heat more quickly, and will reducethe chance of pre-ignition/detonation and melting or damage to the firing end. (Engine temperature can

affect the operating temperature of the spark plug, but not the spark plugs heat range).Below is a list of some of the possible external influences on the operating temperatures of the spark plug.The following symptoms or conditions may have an effect on the actual temperature of the spark plug. Thespark plug cannot create these conditions, but it must be able to cope with the levels of heat, if not, theperformance will suffer and engine damage can occur.3) Air/Fuel Mixtures seriously affect engine performance and spark plug operatingtemperatures.(1) Rich air/fuel mixtures cause tip temperature to drop, causing fouling and poor drivability.(2) Lean air/fuel mixtures cause plug tip and cylinder temperature to increase, resulting in pre-ignition,detonation, and possibly serious spark plug and engine damage.(3) It is important to read spark plugs many times during the tuning process to achieve the optimum air/

fuel mixture.4) Higher Compression Ratios/Forced Induction will elevate spark plug tip and in-cylinder

temperatures.(1) Compression can be increased by performing any one of the following modifications:

Reducing combustion chamber volume (i.e.: domed pistons, smaller chamber heads, milling heads,etc.)

Adding forced induction (Nitrous, Turbo-charging or Supercharging).

Camshaft change.(2) As compression increases, a colder heat range plug, higher fuel octane, and careful attention to ignitiontiming and air/fuel ratios are necessary. Failure to select a colder spark plug can lead to spark plug/enginedamage.5) Advancing Ignition Timing:Advancing ignition timing by 10 Degree causes tip temperature to increase by approx. 70 Degree C to 100


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Degree C.6) Engine Speed and Load:Increases in firing-end temperature are proportional to engine speed and load. When traveling at aconsistent high rate of speed, or carrying/pushing very heavy loads, a colder heat range spark plug shouldbe installed.7) Ambient Air Temperature:(1) As air temperature falls, air density/air volume becomes greater, resulting in leaner air/fuel mixtures.(2) This creates higher cylinder pressures/temperatures and causes an increase in the temperature of thetip of the spark plug. So, fuel delivery should be increased.

(3) As temperature increases, air density decreases, as does intake volume, and fuel delivery should bedecreased.8) Humidity:

(1) As humidity increases, air intake volume decreases.(2) Result is lower combustion pressures and temperatures, causing a decrease in temperature of the sparkplug and a reduction in available power.(3) Air/fuel mixture should be leaner, depending upon ambient temperature.9) Barometric Pressure/Altitude:(1) Also affects temperature of the tip of the spark plug.(2) The higher the altitude, the lower cylinder pressure becomes. As the cylinder temperature decreases,so does the temperature of the tip of the spark plug.

(3) Many mechanics attempt to "chase" tuning by changing spark plug heat ranges.

(4) The real answer is to adjust jetting or air/fuel mixtures in an effort to put more air back into the engine.2. Types of Abnormal Combustion

1) Pre-ignition:(1) Defined as: ignition of the air/fuel mixture before the pre-set ignition timing mark.(2) Caused by hot spots in the combustion chamber can be caused (or amplified) by over advanced timing,too hot a spark plug, low octane fuel, lean air/fuel mixture, too high compression, or insufficient enginecooling.(3) A change to a higher octane fuel, a colder plug, richer fuel mixture, or lower compression may be inorder.(4) You may also need to retard ignition timing, and check cooling system of the vehicle.(5) Pre-ignition usually leads to detonation; pre-ignition and detonation are two separate events.2) Detonation:

(1) The worst enemy of the spark plug! (Besides fouling)

(2) Can break insulators or break off ground electrodes.(3) Pre-ignition most often leads to detonation.(4) Plug tip temperatures can spike to over 3000 Degree F during the combustion process (in a racingengine).(5) Most frequently caused by hot spots in the combustion chamber. Hot spots will allow the air/fuelmixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, thepre-ignited explosion will try to force the piston downward. If the piston can not go up (because of the forceof the premature explosion) and it can not go down (because of the upward motion of the connecting rod),and the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. Thisis detonation.(6) Most of the damage than an engine sustains when "detonating" is from excessive heat.(7) The spark plug is damaged by both the elevated temperatures and the accompanying shock wave, orconcussion.3) Misfires:

(1) A spark plug is said to have misfired when enough voltage has not been delivered to light off all fuelpresent in the combustion chamber at the proper moment of the power stroke (a few degrees before topdead center).(2) A spark plug can deliver a weak spark (or no spark at all) for a variety of reasons, defective coil, toomuch compression with incorrect, plug gap, dry fouled or wet fouled spark plugs, insufficient ignition timing,etc.(3) Slight misfires can cause a loss of performance for obvious reasons (if fuel is not lit, no energy is beingcreated).(4) Severe misfires will cause poor fuel economy, poor drive ability, and can lead to engine damage.4) Fouling:(1) Will occur when spark plug tip temperature is insufficient to burn off carbon, fuel, oil or other deposits.(2) Will cause spark to leach to metal shell...no spark across plug gap will cause a misfire.(3) Wet-fouled spark plugs must be changed...spark plugs will not fire.


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(4) Dry-fouled spark plugs can sometimes be cleaned by bringing engine up to operating temperature.(5) Before changing fouled spark plugs, be sure to eliminate root cause of fouling.5) How to read Spark Plug:Ex) BPR5EY

B: Bolt diameter (14mm).P: insulator shape

R: Resistor spark plug (Using 5KOhms ceramic resistor), 5: Heat range.

E: Bolt length (19mm).

Y: tip type.(V-Power plug)

(BK type is 2.5mm shorter than BP type in total length)

Resistance spark plug

The spark plug named (xxRxxxx) has ceramic resistance to reduce noise from ignition system.

6) Installation:

(1) Tighten the spark plug with hand by when the gasket (washer) is contact to cylinder block.

(2) In case of brand new spark plug, turn 180 Degree more.

(3) In case of used spark plug, turn 30 Degree more.

(4) If torque wrench is used, keep the tightening torque (2.5~3.0kg-m).

You can check the actuator actual value and status and activate it when it is possible by AutoHexautomotive Diagnostic Scanner under the supported car brand and according to engine type.

Ignition Coil


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Ignition Coil Types

1. General

The Ignition coil functions as an energy-storage device and transformer. It is supplied with DC voltage fromthe alternator, and provides the high tension ignition pulses for the spark plugs.The MFI engine adopts a computerized ignition system. The ECM calculates ignition timing, timing advance,and knocking control by the sensor signals.2. Types of Ignition Coils:


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There are distributor type and distributorless types in the ignition system.(1) Distributor TypeIn the distributor type, high voltage is generated at the ignition coil. It is distributed to 4 cylinders using thedistributor. In general, the primary coil is controlled by the power transistor.Therefore, energy is charged in the primary coil while the transistor is on. High voltage generates at thesecondary coil when the transistor turns off. Then high voltage is distributed to the spark plugs by thedistributor.(2) Distributorless Type2 or more of the ignition coils are installed in the distributorless type. The ECM directly controls the primary

coil, and the High voltage is distributed to each cylinder without a distributor.In the distributorless type, sometimes the primary coil is controlled by the power transistor. In that case,the power transistor is installed inside the ignition coil. The operations of the ignition coil and powertransistor are the same as that of distributor type.3. Checking

The checking method of the ignition system is as follows:

Spark test:To perform the spark test, remove the high-tension cable from the spark plug, and check the spark

generation from the high-tension cable.

For reference, when engine idle condition is not good, remove the high-tension cable of eachcylinder one by one and perform power balance test, which compares the engine condition. Through

this test, we can find the trouble cylinder, and we can solve the problem by inspecting the fuel

system, ignition system, combustion chamber pressure, which may influence on the combustion in

the corresponding cylinder.

Checking the coil resistance:To check the coil resistance, remove the coil connector and measure the primary coil resistance at

the connector. As for the secondary coil resistance, remove the high-tension cable and measure the

resistance of the secondary coil. Since each coil resistance value differs depending on the engines,

please refer to the shop manual for the correct values.

Measuring the waveform of primary ignition coil in cranking or idle state:To check the waveform, measure it at the primary coil. The waveform at the primary coil on timing

should looks like the waveform on the screen. If not, check the battery voltage, ground condition,

spark plug, and high tension cable and power transistor.

Exhaust Gas Recirculation


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EGR System Control Operation


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EGR System Control Types 1. Function

Exhaust gas contains NOx that is hazardous to human central nervous system and mucousmembrane, as well as is globally principal cause for photochemical smog, and therefore globallysubject to increasingly strong regulation together with HC and CO. As CO and HC are resulting fromimperfect combustion, improved combustion will improve engine performance, too. However NOxincreases as combustion maximum temperature and in particular rapidly increases typically above2000 Degree C of combustion temperature, combustion maximum temperature shall be lowered inorder to decrease NOx.As lowering combustion maximum temperature is an effective way to actually reducing NOx, they

partly recirculates exhaust gas (approx. 15% of intake mixture) to take initial gas (CO2) intocombustion chamber. Then recirculates exhaust gas will not burn and therefore combustiontemperature at explosion will be decreased to reduce NOx significantly (max. 60%). However EGRwill degrade ignition characteristics of the mixture and consequently reduce engine output, though

EGR is effective for NOx reduction. In addition HC and CO in emission gas may increase, if EGR rateis not appropriate. Therefore it is important to take operation range in which much NOx isgenerated, and recirculates proper quantity of exhaust gas in the range.

2. Configuration and Operation Principle When vacuum pressure occurs at vacuum port located near to throttle valve, the pressure will be

delivered through vacuum hose, and nipple to vacuum chamber. Then the pressure will operate onvacuum pressure chamber diaphragm and consequently push up needle valve that is combined withthe diaphragm, from valve seat, making gap.

The gap will then provide route for exhaust gas going into intake manifold, and depending on thevacuum pressure applied to vacuum pressure chamber of the EGR valve, needle valve lift andconsequently exhaust gas route area varies. Proper control of vacuum pressure applied to vacuumpressure chamber of EGR valve depending on engine operation condition, will provide optimal EGR.


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3. EGR System Control Types: Depending on vacuum chamber of the EGR valve, vacuum pressure control type, vacuum pressure

controlled type may be classified into mechanical type that typically use low EGR of EGR rate, 5~15

%, and electronic control type use high EGR of EGR rate, above 15 %.

(1) Vacuum Pressure Controlled Type

It is the most basic control type that controls EGR valve using vacuum pressure generated near to

throttle valve. In idling or with throttle valve wide open, vacuum of the port will be low enough to

be defeated by spring force of the EGR diaphragm, and then EGR valve will close and quit EGR.

Otherwise EGR rate that is recirculated through EGR valve to intake manifold will be decided

depending on magnitude of port vacuum.

(2) Back Pressure Controlled Type

This type controls EGR valve depending on the finding that there is almost typical relation between

exhaust gas back pressure and air intake rate.

BPT (Back Pressure Transducer) valve controls EGR vacuum pressure to maintain and orifice

downstream vacuum always constant. Then EGR quantity will be proportional to air intake rate, and

EGR rate will be decided depending on orifice section area.

When throttle valve opens, port (E) vacuum will rise and then defeat spring force of the EGR valve

vacuum chamber consequently resulting to EGR valve opening. Therefore exhaust gas will be

recirculated to intake manifold making pressure of the venturi part decrease. When pressure of the

venturi part decreases to atmospheric pressure, BPT will open connecting between port (E) vacuum

and port (A) (atmospheric pressure), and then EGR valve will close. Upon EGR valve closing, back

pressure will rise to close. Therefore port (E) vacuum will be applied to vacuum pressure chamber

of the EGR valve, and then EGR valve will open recirculating exhaust gas to intake manifold.

Repeating this operation, EGR rate will be controlled properly responding to air intake rate.

(3) Electronic Controlled Type

This type uses engine operating condition data detected by various sensors and signals provided by

microprocessor, in order to operate actuator and then control EGR valve opening.

(4) Solenoid Valve

EGR SOL/VLV relies on electromagnet principle, and consists of coil, core, and yoke which generate

magnetic field, plunger and valve seat which open/close air flow and orifice which controls flow

rate.

The operating principle is: When ECU manages to approve power supply at EGR, electromagnetic

force will be generated around coil making core a electromagnet, that will pull plunger closing flowroute, then power supply will be cut off, and spring force will re-open the flow route.


Diagnostic Scanner under the supported car brand and according to engine type.

Purge Control Solenoid Valve

Purge Control Solenoid Valve


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Purge control system

1. Function

A vehicle generates evaporated gas at fuel system such as fuel tank, and HC is the main substance of the

gas. Fuel tank requires venting system to avoid pressure rising in the tank when raised temperaturegenerates volume expansion, and there after resulting vacuum pressure. In addition, vapor gas controlsystem is required to prevent fuel vapor from being discharged into atmosphere.Vapor gas control types include crankcase capturing type and activated charcoal capturing type. Activatedcharcoal capturing type is the most widely used type.Activated charcoal absorbs fuel vapor very well, and thereafter when blowing air, separates the fuel vaporagain. Upon stopping engine, charcoal canister captures vaporized fuel.During engine running the outside air will blown into the canister separating absorbed fuel out of thecharcoal, and route and purge the fuel into intake line.The Purge control solenoid valve controls vaporized gas which is captured in the canister.Depending on control signal of the ECU, the valve delivers the gas into intake line or interrupts it.

(1) Line from fuel tank to carbon canister(2) Carbon canister(3) Fresh air

(4) Purge control valve(5) Line to intake manifold(6) Throttle valve2. Configuration and Operation Principle

Purge control solenoid valve consists of canister, hose connectors at both ends connected with intake line,ECU terminal. And solenoid and spring located inside.

Purge Control Solenoid Valve controlled by on-off only control type using vacuum pressure of theintake manifold and ECU. The valve will close when coolant temperature is low or engine is idling

and open when engine reaches normal operating temperature to deliver vapor gas caught in

canister toward intake manifold.

Purge Control Solenoid Valve controlled by duty controlled type depending on ECU, The valve typethat is duty controlled by ECU is particularly called PCSV (purge control solenoid valve), which is

controlled by microprocessor using vacuum pressure of the intake manifold, the signal of coolant

temperature sensor, etc. Typically the valve closes at 9% duty and wide open at 100% duty.


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3. Vaporized Gas Control System Operation

Typically purge control solenoid valve operates at the following condition:

Coolant temperature at approx. 80 degree C or above. Operating status other than idling.

Not learning idle mileage.Purge control is not a continuous operation. Purge control operates for a certain period (ex. 3

minutes), and stop for a certain period in order to capture vapor gas. Purge control duty rate is

decided principally by engine rpm, and load.

There are purge control solenoid valve check method, checking waveform and checking valve

condition.

To check the waveform, measure the waveform at the ECM connection line.

When the purge control solenoid valve turns on, check whether the voltage becomes close to 0 volt.

And check whether voltage becomes the same with the battery voltage when it turns off. If not,

check the wiring, fuse and ECM ground condition.

To check the valve condition, check the opening condition and closing condition of the valve using a

vacuum pump.


auto Diagnostic Scanner under the supported car brand and according to engine type.

Variable Intake Control

Variable Intake Control 1


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Engine ECU opens VIS valve at high rpm and high load in order to make shorter intake route thanconventional engines, and consequently reduce intake resistance. Then the reduced intake resistance willmake intake efficiency relatively higher and result to increased engine output.

High rpm and high load operation condition.

Engine revolution: 4500rpm or less.

Throttle valve opening: 70% or less.For controlling variable intake system as described above, valve position sensor located at motor

axis detects VIS valve position.

Valve position sensor is installed on valve axis in order to detect accurate valve position when

opening/closing valve. Valve position sensor is made of semiconductor, and operates with the same

principle as HALL sensor. When engine is switched on, ECU will drive the servo motor to sufficiently

close valve. Then valve will contact stopper. This status is initial setting. Thereafter, valve opening

will be calculated depending on number of pulse signals. From full close status through full open

status of valve, the sensor will receive total twelve pulse signals.


automotive Diagnostic Scanner under the supported car brand and according to engine type.

Cooling Fan Control

Cooling Fan Function


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Cooling Fan Control

Cooling Fan Control Outline

In order to maximize cooling efficiency and minimize cooling fan motor drive current, radiator fan and

condenser fan speeds are controlled using three speed modes such as low, medium, and high speed, on the

basis of coolant temperature, car speed, air conditioning switch signal, and conditioning compressor

operation signal.

Cooling fan speed is controlled using three speeds as low, medium, and high speed by ECU that grounds LO

terminal, HI terminal or both terminals to control the speed.

The relays are controlled depending on engine logic table using coolant temperature and car speed as

important variables. Conventional cooling fan control relies on coolant temperature. On the contrary carspeed is also used for this type of advanced control.



Cooling Fan Control Keywords:

diagnostic scanner

Cooling Fan Control Related pages:

AutoHex Scan Tool Specification Cooling Fan Control Idle Speed ActuatorDescription

In order to maximize cooling efficiency and minimize cooling fan motor drive current, radiator fan and

condenser fan speeds are controlled using three speed modes such as low, medium, and high speed, on the

basis of coolant temperature, car speed, air conditioning switch signal, and conditioning compressor

operation signal.
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AutoHex Auto Scan Tool

With AutoHex onboard diagnostic scan tool you can change the configurations of the car by the professional

special functions in HexDiag software

Generator Current Control



1. Generator Current Control Outline

When turning on headlamp or heating wire in idling, engine rpm will instantly fall down and then recovered

due to increased generator load. At that time increasing electrical load will generate rapid engine rpmchange, resulting to vibration and poor comfortableness.
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Generator current control system depends on engine ECU that controls current output from generator inorder to prevent drop of engine rpm when inputting electrical load.2. Generator Current Control Operation

As for generator current control, Engine ECU duty-controls G terminal and consequently the current

provided to rotor coil.

When duty level of G terminal is high, TR1 will be on and current at S terminal flow to ground, and zener

diode will be off. Then TR2 will be off and then TR3 on. Therefore current will flow through rotor coil, and

then generator operates to output current.

On the other hand when G terminal duty level is low, supply current at L terminal flows to engine ECU,

turning TR1 off. Then if voltage between L and S terminal is 14.7V or higher, current will flow through zener

diode, turning TR 2 on. Then, TR3 will be off and no current will flow through rotor coil, disabling power

generation.

G terminal duty-control varies depending on target generating rate. Generated current will be calculated

using time (on) of the FR terminal and engine rpm together. When time (on) of FR terminal and engine rpm

rise, the duty rate of G terminal will increase to rise current generation.

Repeated control of G terminal performed by high rate duty operation as said above, will realize optimum

current generation.

In order to measure FR signal, engine ECU provides 12V power supply at terminal B11, and connected with

TR3 via wiring. When TR3 is on, say current flows through generator rotor coil to generator, voltage at FR

terminal will drop to 0V (low level). On the contrary, if TR3 turns off, the terminal voltage will remain at

12V (high level). FR signal measurement will be decided by comparing and analyzing between generatingperiod by generator, say period of FR terminal remaining at low level, and crank angle sensor.


Automotive Diagnostic Scanner under the supported car brand and according to engine type.

A/C Compressor Control

AC Compressor Control Circuit

1. A/C Compressor Control Outline

A/C Compressor Control is used when accelerating or engine load is instantly increased greatly, in order to

improve engine acceleration by temporarily turning off A/C compressor.2. A/C Compressor On/Off Control

A/C Compressor On/Off Control is performed by engine ECU depending on A/C switch signal and blower fanswitch input signal. When driver turns on A/C switch and blower fan switch, battery voltage will be deliveredthrough fin thermo switch and triple switch inside low & high switches to engine ECU terminal C13.Then engine ECU drives A/C compressor relay, to operate A/C compressor. In addition when throttle valveposition sensor output voltage rises above 4.1V during A/C compressor control, say during passing or rapidacceleration, ECU will turn off A/C compressor for approx. five seconds for improving running performanceof the car. Thereafter A/C compressor will be on again.

A/C compressor control can also perform the below functions:


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A/C compressor off at engine start-up for eight seconds.

A/C compressor off for protecting engine when coolant temperature is above 115 degree C. A/C compressor off when idle speed control system is failed.

You can check the actuator actual value and status and activate it when it is possible by AutoHex AutoDiagnostic Scanner under the supported car brand and according to engine type.A/C Compressor Control Keywords:

diagnostic scanner

Control Relay Control

Control Relay Circuit

Control relay consists of main relay that provides supply power to engine ECU and various actuators and

fuel pump relay that drives fuel pump.

Main relay control will operate as soon as ignition switch turns on.

Turning ignition switch on, IG supply power will be, input through control relay terminal 8, and then the

power supply will flow through magnetizer coil (L2) and then control relay terminal to engine ECU terminal

B09.

As current flows through magnetizer coil (L2), main relay operates.

When main relay operates, IG supply power at control relay terminal 4 will go through main relay contact to

control relay terminal 2 and terminal 3, and then the current will supply power to engine ECU and various

actuators.

As to fuel pump relay control, when turning on ignition switch current will flow through control relay

terminal 7, and then magnetizer coil (L1) to engine ECU terminal A20.

Then ECU of the engine fuel pump relay control function will control fuel pump operation turning on/off

engine ECU terminal A20, depending on engine rpm.

Fuel pump relay will not operate at engine speed of 50rpm or less and operate only at engine speed of

50rpm or above when ignition switch is on.

Without the logic, fuel pump will continue to operate though car accident occurs with IG key on, and then

may generate fire by fuel leak. Therefore the logic is newly added to prevent possible fire under car

accident.
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Documents

Vehicle Electrical Actuators