ATASA 5 Electrical Service & Diagnosis - School … 5 TH Study Guide Chapter 16 Pages 457 500 Electrical Service & Diagnosis 70 Points ATASA 5 th Electrical Service & Diagnosis

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


2. An ________ problem prevents a circuit from operating.


Open Short High Resistance

2. A __________ to ground reduces resistance and increases current flow to blow the fuse.



2. A __________ to power or “shorttohot” energizes an unwanted circuit.



_ +

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


_ +

Short to hot energizes the circuit at all times


_ +

H

_ +

H Horn circuit uses

“groundside” switching.

Short to ground energizes this circuit at all times.


2. High resistance in a path reduces _____________ flow. (less intensity in bulbs, less speed in motors)


Voltage Current (amperage) Resistance

Parallel Lighting Circuit that is ground side switched

_ +


_ +

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


4. Wiring diagrams called _____________ show how a circuit is constructed or arranged.


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


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


6. Besides multimeters, ____________ wires, test lights and logic probes are used for diagnosis.

Jumper Bumper Thumper


7. Nonpowered 12volt test lights are used to check for voltage ____________.

Drops Available Consumption


8. A ________ _______________ test light is used to check for continuity.

12Volt SelfPowered 1.5 Volt


Logic Probe ATASA 5 th Electrical Service & Diagnosis

9. ______ ____________ are fast reacting meters that measure & display voltage over time.

Lab Rats Lab Tasks Lab Scopes


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


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


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


13. A DMM used on computer circuits should have an input _______________ of 1 MΩ to 10 MΩ.

Resistance Impedance Capacitance


14. A DMM used on high voltage hybrid vehicles should be ANSI & SCA _____ 1000 V rated.

CAT I CAT II CAT III


15. The auto ___________ feature on meters detects the proper range & sets the meter to read it.

Ranging MN/MAX Averaging


16. A DMM set to measure volts is connected in ____________ to a circuit.

Series Parallel Inductively


V Ω

COM A

V A

V A

OFF

Ω

12.6 V Source Voltage

Carbon Pile Current Clamp


17. Voltage _______ tests will find excessive resistance that may not be detected with an ohmmeter.

Drop Available Capacitance


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


18. Ammeters are connected either in series or using ________________ pickups to measure current.

Inductive Deductive Conductive



19. Ohmmeters are always used on components disconnected from their _______ source. (open = OL)

Voltage Amperage Resistance


Remember to Zero your meter before you start measuring!


20. The DMM _______________ test mode (alert) sounds an audible beep when continuity exists.

Continuity Hertz Smooth


21. The DMM ______ / ______ is a record function that is useful in capturing intermittent problems.

MIN/MAX Pulse Width Smooth





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


23. On a lab scope, voltage is shown on the ________________ axis.

Vertical Horizontal Z


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


Note: The sweep of a scope pattern is another name for the time axis.


Frequency is a term that describes how often a signal performs a complete cycle.


A cycle is a description of the changes that a signal goes through without repeating itself.


Frequency is measured in Hertz. Hertz is a measurement of Cycles per Second.


26. An ____________ scope is a realtime scope. A ______ is a Digital Storage Oscilloscope.

Analog, Digital


27. Using a DSO, a technician can “_______________” or capture a signal for closer analysis.

Freeze Pinpoint Movie


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


B1, S1 HO2S

B1, S2 HO2S




29. Waveform amplitude is shown as ________ & waveform frequency is shown as ___________.

Voltage, Frequency


30. One complete sine wave is a __________. One cycle per second is 1 hertz.

Cycle Frequent Repeat


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


32. Many DSOs and GMMs allow capture & transfer of screens & data to a PC. True or False


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



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


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.



36. Testing of __________ can be done with jumper wires, a volt meter, ohmmeter, or a test light.

Relays Relays Relays



30

85 85

87

87a

85 86 30

87 87a

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





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.


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 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




39. The best way to check wiring is to check the __________ _______ across it.

Current Voltage Available Voltage Drop


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


41. When __________ probing, using too large of an adapter can deform & loosen terminals.

Front Back Side


42. _________ probing is necessary when tests like voltage drop need to be done on a “live” circuit.


Front Back Side

43. If you test wiring by ___________ through the insulation, cover the damage to prevent corrosion.


Piercing Slicing Dicing

44. For circuit diagnosis a __________ diagram is one of the most important sources of information.

Wiring Vacuum Symptom


45. Connectors and _________ are typically numbered to make location easier. (Cxxx Sxxx Gxxx)

Grounds Wires Bulbs


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!


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


48. All circuit issues can be boiled down to 1 of 3 things: ______, _______ & high _____________.

Opens, Shorts, High Resistances Fuses, Wiring, Consumers Grounds, Splices, Connectors


49. A component with a shorted coil of wire will read __________ than specs or even zero resistance.

Greater Less Same


50. “A fuse never blows without a reason”, probably blown due to a _________ to ground.



51. High resistance problems are typically caused by _____________ that decreases intensity. (amps)

Corrosion Solder Electrical Tape


52. Many electrical problems can be traced to faulty wiring or _____________.

Connections Splices Grounds


53. Rerouting wires can result in unwanted _____________ voltages from electromagnetic fields.

Induced Reduced Seduced


54. All replacement wires should be the ______ size or larger than the original, never smaller.

Same Same Same


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


56. When soldering near heatsensitive components, use a heat ________ to prevent damage.

Shrink Sink Stick


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.


Meat Heat Cold

58. Wire terminal ________ and release tools prevent connector damage when unlocking terminals.

Picks Sticks Tricks


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ATASA 5 Electrical Service & Diagnosis - School … 5 TH Study Guide Chapter 16 Pages 457 500 Electrical Service & Diagnosis 70 Points ATASA 5 th Electrical Service & Diagnosis