Deck 19: Charging Systems

Question 1

A PCM-controlled AC generator controls charging system voltage by shunting its excess output.

Answer 1

False

Question 2

Testing the voltage regulator circuit by full fielding the alternator is a common diagnostic technique on modern cars.

Answer 2

False

Question 3

AC generators produce overlapping sine waves three-phase voltage.

Answer 3

True

Question 4

Which of the following precautions should be followed whenever working on or testing a charging system?

A) Make sure a load is on the system before energizing the AC generator
B) Ground the alternator's output terminals
C) Disconnect the positive side of the battery before disconnecting any wire to and from the AC generator or battery
D) All answers are correct

Question 5

All AC generators use an internal fan to move air across the components for cooling.

Question 6

A lab scope can be used to check for open or shorted diodes in the rectifier.

Question 7

Late model vehicles with PCM-controlled AC generators can generate more engine power due to decreased magnetic drag caused by the AC generator.

Question 8

Which of the following is NOT a way to increase the amount of voltage induced in an AC generator?

A) Increase the number of conductors
B) Move the conductors through the magnetic field slowly
C) Move the conductors at a right angle to the magnetic field
D) Increase the current going through the electromagnet

Question 9

The output of an AC generator can be as high as 250 volts if it is not controlled.

Question 10

An alternator is also called an AC generator.

Question 11

The current output in an AC generator must be limited by a resistor to prevent excess current from damaging the battery and electrical accessories.

Question 12

Some AC generators have dual fans to move air across the components for cooling.

Question 13

A bad diode can cause an abnormal whirring noise in the AC generator.

Question 14

On a B circuit AC generator, the regulator is on the negative side of the circuit.

Question 15

Most AC generator stators use three windings to generate the required amperage output.

Question 16

Most late model vehicles do not have a separate voltage regulator. Instead, voltage regulation is a function of the PCM.

Question 17

The voltage regulator controls voltage by varying the field current through the rotor.

Question 18

Rectification refers to changing alternating current to direct current.

Question 19

A zener diode is a special type of diode that blocks the current when the polarity is reversed, but only as long as the voltage is low. When the voltage rises above a critical level, the current can flow through it in a reverse direction.

Question 20

An AC generator cannot be liquid-cooled.

Question 21

A diode trio provides rectified current to the ______.

A) field coil
B) stator coil
C) battery
D) ignition switch

Question 22

Oscilloscope patterns are being discussed; Technician A says an open or shorted diode can be detected by the waveform on a lab scope without removing the generator from the vehicle. Technician B says the waveform produced by the AC generator after the output moves through the diodes is a straight line because it is a constant DC voltage. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 23

Technician A says electricity can be generated by moving a magnetic field across an electrical conductor. Technician B says electricity can be generated by moving an electrical conductor across a magnetic field. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 24

Which type of stator winding produces high AC generator charging voltage at low speeds?

A) wye
B) delta
C) trio
D) series

Question 25

Hybrid vehicles are being discussed. Technician A says some hybrid vehicles use a motor/generator that is connected to the crankshaft by a drive belt. Technician B says the motor/generator on a hybrid vehicle is located at the flywheel. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 26

Slip rings and brushes ______.

A) mount on the rotor shaft
B) conduct current to the rotor field coils
C) are insulated from each other and the rotor shaft
D) all answers are correct

Question 27

Which part of the AC generator produces the moving magnetic field?

A) stator
B) rotor
C) brushes
D) poles

Question 28

A voltage drop over _____ volt(s) indicates high resistance in either the circuit or ground wiring of the charging system.

A) 0.1
B) 0.2
C) 0.5
D) 1.0

Question 29

Technician A says an a circuit has the regulator on the positive side of the field coil. Technician B says on an isolated field circuit, the regulator may be on the negative or the positive side. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 30

A rotating magnetic field inside a set of stationary conducting wires is a simple description of a(n) ______.

A) DC generator
B) AC generator
C) voltage regulator
D) none of these answers is correct

Question 31

When checking AC generator output using an oscilloscope, the correct pattern resembles ______.

A) the rounded tops of a picket fence
B) a square sine-wave pattern
C) a square wave
D) a sawtooth wave

Question 32

Technician A says the charging system recharges the battery by supplying a constant and relatively low charge to the battery. Technician B says the charging system works on the principles of magnetism to change mechanical energy into electrical energy. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 33

Integrated voltage regulators ______.

A) mount to the back of or inside the AC generator housing
B) may be integrated with the brush holder assembly
C) are not serviceable and must be replaced if defective
D) all answers are correct

Question 34

Technician A says increasing the strength of the magnetic field in an AC generator increases the voltage output. Technician B says the voltage regulator controls the strength of the rotor's magnetic field. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 35

Before adjusting drive-belt tension, Technician A checks for proper pulley alignment. Technician B looks up the specified belt tension in the vehicle's service manual. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 36

Technician A says the magnetic field in an AC generator is stationary. Technician B says the rotor in an AC generator is driven by a belt. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 37

Technician A says a DC generator is similar in construction to an electric motor. Technician B says DC generators have limited output, especially at low speeds. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 38

The alternating current produced by the AC generator is rectified into DC (direct current) through the use of ______.

A) transistors
B) electromagnetic relays
C) diodes
D) capacitors

Question 39

Voltage regulator circuitry in the computer control module controls AC generator output by ______.

A) using a variable resistor to vary current flow to the rotor field windings
B) pulsing current flow to the rotor field windings on and off to create a correct average field current supply
C) both "using a variable resistor to vary current flow to the rotor field windings" and "pulsing current flow to the rotor field windings on and off to create a correct average field current supply"
D) neither "using a variable resistor to vary current flow to the rotor field windings" nor "pulsing current flow to the rotor field windings on and off to create a correct average field current supply"

Question 40

Technician A uses a current output test to check AC generator output. Technician B uses a voltage output test to check output. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 41

The alternating current produced by the AC generator is rectified into DC (direct current) through the use of ____________________.

Question 42

Recommended engine rpm during a voltage output test is usually around ____________________ rpm.

Question 43

Hybrid vehicles are being discussed. Technician A says some hybrid vehicles use a motor/generator that is connected to the crankshaft by a drive belt. Technician B says the motor/generator on a hybrid vehicle is located at the flywheel. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 44

With no electrical load, charging voltage during a voltage output test should be approximately ____________________ volts higher than during an open circuit voltage test.

Question 45

The ____________________ is the stationary member of the AC generator.

Question 46

Most newer vehicles do not have a separate voltage regulator and control the output of the charging system through the ____________________.

Question 47

Most electronic voltage regulators use a ____________________ diode that blocks current flow until a specific voltage is obtained.

Question 48

Bypassing the regulator is known as ____________________ the generator.

Question 49

If the field of a 100 amp, pulse width modulated AC generator [PCM controlled] is fed a 30% duty cycle, how much current will be produced at the generator output terminal?

A) 0 amps
B) 30 amps
C) 70 amps
D) 100 amps

Question 50

A technician connects the red lead of a voltmeter to the B+ [output] terminal of an AC generator and the black lead to the battery positive terminal. He starts the engine and turns on all the lights and electrical accessories. What is the technician measuring?

A) resistance in the positive side charging system cables
B) diode leakage
C) charging voltage
D) charging current

Question 51

A whining noise from a malfunctioning AC generator may be caused by a bad ____________________.

Question 52

What type of test equipment is needed to perform a charging system current output test?

A) an ammeter
B) a voltmeter
C) a lab scope
D) a VAT with a carbon pile

Question 53

PCM-controlled AC generators are being discussed. Technician A says the battery current sensor is located inside the AC generator. Technician B says the battery current sensor is a three-wire hall effect type sensor that connects to the PCM. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 54

The bearings that support the rotor shaft are located on the ______.

A) stator housing
B) end frames
C) rectifier
D) tensioner bracket

Question 55

Air cooling or liquid cooling is required in an AC generator to maintain the temperature of the _____.

A) stator
B) rotor
C) voltage regulator
D) diodes [rectifier]

Question 56

Technician A says the charging system is needed to keep the battery fully charged and recharge the battery after starting. Technician B say the charging system supplies all the vehicle's electrical current needs after the engine starts. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 57

On a PCM-controlled AC generator, system voltage is controlled by varying the _____ of the current applied to the field coil.

A) frequency
B) duty cycle
C) bandwidth
D) amplitude

Question 58

A voltage regulator controls the voltage output of an AC generator by controlling the current through the ____________________.

Question 59

The motor/generator in a hybrid vehicle ______.

A) generates electricity when the engine is running
B) acts as a starter motor
C) slows the vehicle when the brakes are applied
D) all answers are correct

Question 60

Voltage regulators are being discussed. Technician A says charging voltage is decreased when the battery temperature is low because the battery cannot accept high charging rates at low temperatures. Technician B says the voltage regulator increases the current flowing through the field coil when the battery voltage is low. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 61

Describe the steps in a charging system voltage test.

Question 62

How does a voltage regulator control AC generator voltage output?

Question 63

Circuit resistance is checked by connecting a(n) ____________________ to the positive battery terminal and the output, or battery terminal of the AC generator.

Question 64

A ____________________.circuit in the voltage regulator prevents simple electrical problems such as corroded output terminals from causing high-voltage outputs that could damage delicate electronic components.

Question 65

What is the purpose of the fail-safe circuit contained with many voltage regulators?

Question 66

What is pulse width modulation?

Question 67

What are the four types of charging system failure warning systems?

Question 68

Identify four internal problems of faulty AC generators.

Question 69

What factors determine whether a faulty AC generator should be replaced or rebuilt?

Question 70

"A one-way check valve for electric current" is a good description of a ____________________.

Question 71

____________________ braking is the process of using the motor/generator to convert kinetic energy into electrical energy to recharge the batteries while slowing the vehicle.

Question 72

Describe how to test a rotor for a short to ground.

Question 73

How does voltage regulation circuitry located within a PCM control the AC generator output?

Question 74

What is the purpose of a diode trio?

Question 75

How can an oscilloscope be used to check AC generator output?