Upload
nguyendang
View
221
Download
3
Embed Size (px)
Citation preview
ATASA 5 TH Study Guide Chapter 16 Pages 457500 Electrical Service & Diagnosis 70 Points
ATASA 5 th Electrical Service & Diagnosis Please Read the Summary
1. All Electrical problems can be categorized into one of three categories:
Open Consumer
Open Conductive Path
Opens
Shorts
High Resistances
ATASA 5 th Electrical Service & Diagnosis
OPENS occur when a circuit is incomplete.
Open Consumer
Open Conductive Path
ATASA 5 th Electrical Service & Diagnosis
2. An ________ problem prevents a circuit from operating.
ATASA 5 th Electrical Service & Diagnosis
Open Short High Resistance
2. A __________ to ground reduces resistance and increases current flow to blow the fuse.
ATASA 5 th Electrical Service & Diagnosis
Open Short High Resistance
2. A __________ to power or “shorttohot” energizes an unwanted circuit.
ATASA 5 th Electrical Service & Diagnosis
Open Short High Resistance
_ +
12 v. source
6 Ω resistor
2 amp normal current flow
1 Ω in shorting wire causes 12 amps of flow & blows the fuse… …when the switch is turned on
ATASA 5 th Electrical Service & Diagnosis SHORTS occur when a circuit has an unwanted path for current.
_ +
1 Ω in shorting wire causes 12 amps of flow & blows the fuse… …as soon as the fuse is replaced
ATASA 5 th Electrical Service & Diagnosis SHORTS occur when a circuit has an unwanted path for current.
_ +
Short to hot energizes the circuit at all times
ATASA 5 th Electrical Service & Diagnosis SHORTS occur when a circuit has an unwanted path for current.
_ +
H
_ +
H Horn circuit uses
“groundside” switching.
Short to ground energizes this circuit at all times.
ATASA 5 th Electrical Service & Diagnosis
2. High resistance in a path reduces _____________ flow. (less intensity in bulbs, less speed in motors)
ATASA 5 th Electrical Service & Diagnosis
Voltage Current (amperage) Resistance
Parallel Lighting Circuit that is ground side switched
_ +
ATASA 5 th Electrical Service & Diagnosis
_ +
High Resistance in common Ground Path decreases intensity (amps) in both bulbs
ATASA 5 th Electrical Service & Diagnosis HIGH RESISTANCE occurs when there is unwanted resistance (corrosion).
High Resistance in one Ground Path decreases intensity (amps) in only one bulb
_ +
ATASA 5 th Electrical Service & Diagnosis HIGH RESISTANCE occurs when there is unwanted resistance (corrosion).
3. Many sensors are fed a ____volt reference signal. Bad grounds (those with excess resistance) can result in higher than normal readings back to the PCM.
5 volt 12 volt 42 volt
ATASA 5 th Electrical Service & Diagnosis
4. Wiring diagrams called _____________ show how a circuit is constructed or arranged.
ATASA 5 th Electrical Service & Diagnosis
Pneumatics Schematics Fanatics
5. Common electric _____________ are used in schematic drawings. Some feature colorcoded wiring that indicates the color of the wire insulation, but no length or location is depicted.
Cymbals Symbols Shapes
ATASA 5 th Electrical Service & Diagnosis
Ground Battery Resistor Variable Resistor Capacitor Fuse Circuit Breaker Thermistor Motor Momentary Switch Switch SPST Connector Lamp or Bulb Coil of Wire NPN Transistor PNP Transistor Diode LED Transformer DMM Relay Wyewound Coil Deltawound Coil Contacts
ATASA 5 th Electrical Service & Diagnosis
6. Besides multimeters, ____________ wires, test lights and logic probes are used for diagnosis.
Jumper Bumper Thumper
ATASA 5 th Electrical Service & Diagnosis
7. Nonpowered 12volt test lights are used to check for voltage ____________.
Drops Available Consumption
ATASA 5 th Electrical Service & Diagnosis
8. A ________ _______________ test light is used to check for continuity.
12Volt SelfPowered 1.5 Volt
ATASA 5 th Electrical Service & Diagnosis
9. ______ ____________ are fast reacting meters that measure & display voltage over time.
Lab Rats Lab Tasks Lab Scopes
ATASA 5 th Electrical Service & Diagnosis
10. A good ________ __________ can do so much more than just read DTC’s! Be sure to use the serial data stream, check TSB’s, use the pattern failure troubleshooter, and all of the modes.
Lead Tech Scan Tool Auto Teacher
ATASA 5 th Electrical Service & Diagnosis
11. Jumper wires with a ________ or a circuit breaker can be used to bypass wires or switches. Do not use a jumper wire to bypass a consumer or a load. The circuit amps will skyrocket.
Fuse Splice Ground
ATASA 5 th Electrical Service & Diagnosis
12. A computer ________ ______ will preserve power to volatile RAMs when the battery is disconnected for service. Note: The SIR system retains its backup power with a memory saver!
Battery Saver Memory Saver RAM/ROM
ATASA 5 th Electrical Service & Diagnosis
13. A DMM used on computer circuits should have an input _______________ of 1 MΩ to 10 MΩ.
Resistance Impedance Capacitance
ATASA 5 th Electrical Service & Diagnosis
14. A DMM used on high voltage hybrid vehicles should be ANSI & SCA _____ 1000 V rated.
CAT I CAT II CAT III
ATASA 5 th Electrical Service & Diagnosis
15. The auto ___________ feature on meters detects the proper range & sets the meter to read it.
Ranging MN/MAX Averaging
ATASA 5 th Electrical Service & Diagnosis
16. A DMM set to measure volts is connected in ____________ to a circuit.
Series Parallel Inductively
ATASA 5 th Electrical Service & Diagnosis
V Ω
COM A
V A
V A
OFF
Ω
12.6 V Source Voltage
Carbon Pile Current Clamp
ATASA 5 th Electrical Service & Diagnosis
17. Voltage _______ tests will find excessive resistance that may not be detected with an ohmmeter.
Drop Available Capacitance
ATASA 5 th Electrical Service & Diagnosis
Think of Voltage Drop as Voltage Use by a consumer
V Ω
COM A
V A
V A
OFF
Ω
0.2 V Voltage Drop
Carbon Pile Current Clamp
ATASA 5 th Electrical Service & Diagnosis
18. Ammeters are connected either in series or using ________________ pickups to measure current.
Inductive Deductive Conductive
ATASA 5 th Electrical Service & Diagnosis
19. Ohmmeters are always used on components disconnected from their _______ source. (open = OL)
Voltage Amperage Resistance
ATASA 5 th Electrical Service & Diagnosis
20. The DMM _______________ test mode (alert) sounds an audible beep when continuity exists.
Continuity Hertz Smooth
ATASA 5 th Electrical Service & Diagnosis
21. The DMM ______ / ______ is a record function that is useful in capturing intermittent problems.
MIN/MAX Pulse Width Smooth
ATASA 5 th Electrical Service & Diagnosis
22. A DMM may also measure _________ _________ which is a percentage of circuit ontime. ____________ _________ normally measured in milliseconds, and ________________ in hertz.
Duty Cycle, Pulse Width, Frequency
ATASA 5 th Electrical Service & Diagnosis
23. On a lab scope, voltage is shown on the ________________ axis.
Vertical Horizontal Z
ATASA 5 th Electrical Service & Diagnosis
24. On a lab scope, time is shown on the _________________ axis. ATASA 5 th Electrical Service & Diagnosis
Vertical Horizontal Z
25. Lab scopes can display momentary electrical noise, disturbances, and signal ______________.
Glitches Snitches Sandwiches
ATASA 5 th Electrical Service & Diagnosis
Note: The sweep of a scope pattern is another name for the time axis.
ATASA 5 th Electrical Service & Diagnosis
Frequency is a term that describes how often a signal performs a complete cycle.
ATASA 5 th Electrical Service & Diagnosis
A cycle is a description of the changes that a signal goes through without repeating itself.
ATASA 5 th Electrical Service & Diagnosis
Frequency is measured in Hertz. Hertz is a measurement of Cycles per Second.
ATASA 5 th Electrical Service & Diagnosis
26. An ____________ scope is a realtime scope. A ______ is a Digital Storage Oscilloscope.
Analog, Digital
ATASA 5 th Electrical Service & Diagnosis
27. Using a DSO, a technician can “_______________” or capture a signal for closer analysis.
Freeze Pinpoint Movie
ATASA 5 th Electrical Service & Diagnosis
ATASA 5 th Electrical Service & Diagnosis Cursors can be used to measure time between 2 points – horizontally.
Cursors can be used to measure voltage between 2 points – vertically.
28. A multiple __________ DSO can display more than one waveform at a time for comparison.
Base Face Trace
ATASA 5 th Electrical Service & Diagnosis
29. Waveform amplitude is shown as ________ & waveform frequency is shown as ___________.
Voltage, Frequency
ATASA 5 th Electrical Service & Diagnosis
30. One complete sine wave is a __________. One cycle per second is 1 hertz.
Cycle Frequent Repeat
ATASA 5 th Electrical Service & Diagnosis
V O L T A G E
TIME
31. A ______ is a DMM that displays voltage, resistance, current & frequency as a waveform graph.
GMM MMM HMM
ATASA 5 th Electrical Service & Diagnosis
32. Many DSOs and GMMs allow capture & transfer of screens & data to a PC. True or False
ATASA 5 th Electrical Service & Diagnosis
33. Measuring ____________ _______ across a fuse or other circuit protection device tells more about its condition than a continuity test.
Voltage Drop Voltage Available Voltage Capacitance
ATASA 5 th Electrical Service & Diagnosis
34. Some systems, like power seat motors use a PTC ______________ as circuit protection. When the current is high, the resistance of the thermistor increases to decrease current or even stop flow.
Thermistor Resistor Transistor
ATASA 5 th Electrical Service & Diagnosis
35. Both manual switches & automatic switches (pressure switch) can be _______ checked, checked for continuity, voltage drop checked or even by passed with a jumper wire to verify operation.
Open Short High Resistance
ATASA 5 th Electrical Service & Diagnosis
36. Testing of __________ can be done with jumper wires, a volt meter, ohmmeter, or a test light.
Relays Relays Relays
ATASA 5 th Electrical Service & Diagnosis
ATASA 5 th Electrical Service & Diagnosis A car relay is a electromagnetic switch that uses a small amount of current to control a larger amount of current.
How they work is by a wire wound magnetic coil that when excited by a electric current, moves a mechanical spring contact inside the relay, completing a circuit.
Car relays are usually controlled by another switch such as your car horn button, headlight switch circuit or power window / door lock switches.
Relays are located all over a car, truck, van, suv or hybrid. They are placed in the engine compartment, fuse box or fuse panel, under the dash board or behind door panels and kick panels. Check your owners manual or service manual for exact placement
30 87a
87
ATASA 5 th Electrical Service & Diagnosis
The control circuit (GREEN) powers the coil inside the relay, using a small amount of current. It flows from the battery, thru the fuse ( for protection) to a
switch, (say, a light switch) then to the coil in the relay, energizing it.
ATASA 5 th Electrical Service & Diagnosis
The coil, now energized becomes an electromagnet, and attracts the metal strip with the contacts, which closes, providing a secondary heavy current path ( RED ) to the device ( say, the fog lights)
Turning off the switch, opens the circuit to the coil, removes current flow, and the electromagnet is no longer a magnet, the secondary path is opened, and the lights extinguish.
As the relay turns off, the voltage spike (inductive kick) will take place in the coil & may need a clamping diode to protect the control circuit.
NOTE: In a basic or resistor protection relay, pins 1 and 2 of the micro relays and pins 85 and 86 of the mini relays can be interchanged positive or negative.
In a diode protected relay, Mini relays must be pin 85 (+) power, pin 86 () ground / Micro relays must be pin 2 (+) power, pin 1 () ground.
Look for a relay diagram or a relay schematic that is printed on the side of the relay to determine.
ATASA 5 th Electrical Service & Diagnosis
ATASA 5 th Electrical Service & Diagnosis Protection Diode = Clamping Diode, Parallel to Coil for Spike Suppression
Current flowing through a relay coil creates a magnetic field which collapses suddenly when the current is turned off. The sudden collapse of the magnetic field induces a brief high voltage across the relay coil that wants to flow in the opposite direction which can cause damage to a ECM, PCM or ICs. A quenching protection diode or suppression
resistor allows the induced voltage a path to block and dissipate. This prevents spiked voltage becoming high enough to cause damage to a electronic control module or a IC.
ATASA 5 th Electrical Service & Diagnosis Spike Suppression Resistor Located Parallel to Coil
Current flowing through a relay coil creates a magnetic field which collapses suddenly when the current is turned off. The sudden collapse of the magnetic field induces a brief high voltage across the relay coil that wants to flow in the opposite direction which can cause damage to a ECM, PCM or ICs. A quenching protection diode or suppression
resistor allows the induced voltage a path to block and dissipate. This prevents spiked voltage becoming high enough to cause damage to a electronic control module or a IC.
37. The best way to test a stepped resistor is with an ohmmeter. True or False ATASA 5 th Electrical Service & Diagnosis
38. An unpowered _______________ can be “sweep tested” with an ohmmeter, preferably a GMM.
Potentiometer Capacitor Transistor
ATASA 5 th Electrical Service & Diagnosis
39. The best way to check wiring is to check the __________ _______ across it.
Current Voltage Available Voltage Drop
ATASA 5 th Electrical Service & Diagnosis
40. When troubleshooting, verify the complaint, then use the wiring diagrams & do quick _____ checks of source & ground to narrow the problem down.
Voltage Amperage Resistance
ATASA 5 th Electrical Service & Diagnosis
41. When __________ probing, using too large of an adapter can deform & loosen terminals.
Front Back Side
ATASA 5 th Electrical Service & Diagnosis
42. _________ probing is necessary when tests like voltage drop need to be done on a “live” circuit.
ATASA 5 th Electrical Service & Diagnosis
Front Back Side
43. If you test wiring by ___________ through the insulation, cover the damage to prevent corrosion.
ATASA 5 th Electrical Service & Diagnosis
Piercing Slicing Dicing
44. For circuit diagnosis a __________ diagram is one of the most important sources of information.
Wiring Vacuum Symptom
ATASA 5 th Electrical Service & Diagnosis
45. Connectors and _________ are typically numbered to make location easier. (Cxxx Sxxx Gxxx)
Grounds Wires Bulbs
ATASA 5 th Electrical Service & Diagnosis
46. When tracing a circuit on a schematic, start at the ______________ that is not working, find its source, its ground, its switch or control, and the circuit protection. Then get busy with the DMM!
ATASA 5 th Electrical Service & Diagnosis
Source Component, Consumer, or Load Ground
This Circuit Has Splices
Connectors Grounds
47. Printing out the circuit & using ______ to trace it can help avoid confusion.
Black Marker Highlighter Lipstick
ATASA 5 th Electrical Service & Diagnosis
48. All circuit issues can be boiled down to 1 of 3 things: ______, _______ & high _____________.
Opens, Shorts, High Resistances Fuses, Wiring, Consumers Grounds, Splices, Connectors
ATASA 5 th Electrical Service & Diagnosis
49. A component with a shorted coil of wire will read __________ than specs or even zero resistance.
Greater Less Same
ATASA 5 th Electrical Service & Diagnosis
50. “A fuse never blows without a reason”, probably blown due to a _________ to ground.
Open Short High Resistance
ATASA 5 th Electrical Service & Diagnosis
51. High resistance problems are typically caused by _____________ that decreases intensity. (amps)
Corrosion Solder Electrical Tape
ATASA 5 th Electrical Service & Diagnosis
52. Many electrical problems can be traced to faulty wiring or _____________.
Connections Splices Grounds
ATASA 5 th Electrical Service & Diagnosis
53. Rerouting wires can result in unwanted _____________ voltages from electromagnetic fields.
Induced Reduced Seduced
ATASA 5 th Electrical Service & Diagnosis
54. All replacement wires should be the ______ size or larger than the original, never smaller.
Same Same Same
ATASA 5 th Electrical Service & Diagnosis
55. _____________ wires (the proper way to connect wires) joins them by melting a lead & tin alloy and allowing it to flow into the joint. 60/40 rosin core solder of a .032” diameter works well.
Welding Twisting Soldering
ATASA 5 th Electrical Service & Diagnosis
56. When soldering near heatsensitive components, use a heat ________ to prevent damage.
Shrink Sink Stick
ATASA 5 th Electrical Service & Diagnosis
57. After crimping & soldering a wire splice, place _________ shrink tubing over the splice, and warm it with a heat gun to protect the joint from elements that could cause corrosion & shorts.
ATASA 5 th Electrical Service & Diagnosis
Meat Heat Cold