Question 1

Technician A says on an electromagnetic field wiper motor the strength of the total magnetic field will determine the motor speed. Technician B says on an electromagnetic field wiper motor the two field coils are wound in opposite directions so their magnetic fields will oppose each other. Who is correct?

Accepted Answer

Technician A is correct because in an electromagnetic field wiper motor, the strength of the magnetic field indeed determines the motor speed; a stronger magnetic field results in a higher speed. Technician B is also correct because having the two field coils wound in opposite directions so their magnetic fields oppose each other is a common design in these motors to control the motor's operation and speed.

Question 2

Blower motor resistor blocks are being discussed, Technician A says if the thermal limiter opens the fan will only operate at high speed. Technician B says if any of the resistors burn out, the blower motor fan will operate at low speed only. Who is correct?

Accepted Answer

The answer of Blower motor resistor blocks are being discussed,...

Question 3

The electric rear window defogger system is being discussed. Technician A says the grid is a series of controlled voltage amplifiers. Technician B says to protect the vehicle's electrical system, a timer circuit may be incorporated. Who is correct?

Accepted Answer

Technician B is correct because a timer circuit is often used in electric rear window defogger systems to protect the vehicle's electrical system by limiting the operation time of the defogger, preventing battery drain and excessive current draw. Technician A is incorrect because the grid is not made up of voltage amplifiers; it is a series of resistive wires that heat up when current passes through them to defog the window.

Question 4

Intermittent wiper systems are being discussed. Technician A says they may use a solid-state module that may be incorporated into the body computer. Technician B says they may use a capacitor that operates the wiper motor directly until it is fully discharged. Who is correct?

Accepted Answer

Technician A is correct in stating that intermittent wiper systems may use a solid-state module that may be incorporated into the body computer. Technician B is incorrect in stating that they may use a capacitor that operates the wiper motor directly until it is fully discharged, as this is not a common method of operation for modern intermittent wiper systems.

Question 5

Slower-than-normal wiper operation is being discussed. Technician A says this may be caused by excessive electrical resistance. Technician B says this may be caused by a problem in the mechanical linkage. Who is correct?

Accepted Answer

Both Technician A and B could be correct. Excessive electrical resistance can cause slower-than-normal wiper operation, but a problem in the mechanical linkage can also cause the same issue. A comprehensive diagnosis will be required to determine the root cause of the problem.

Question 6

Technician A says the power seat system typically uses stepper motors. Technician B says the rotational direction of the power seat motor is determined by the direction current flows through it. Who is correct?

Accepted Answer

Technician B is correct because the rotational direction of a motor, including those used in power seat systems, is indeed determined by the direction of current flow through the motor. Technician A is incorrect because power seat systems typically use conventional DC motors, not stepper motors. Stepper motors are more commonly used in applications requiring precise control of position, which is not typically necessary for power seat adjustments.

Question 7

A two-speed windshield wiper will operate in only the low-speed position. Technician A says the common motor brush is worn. Technician B says the Hi-Lo relay may be faulty. Who is correct?

Accepted Answer

Since the wiper operates only in low-speed, it means the motor is working but not receiving signals for high speed. Hence, there might be a problem with the Hi-Lo relay. Technician B is correct. Worn brush will cause reduced power and slow operation in both the high and low-speed modes. Hence, Technician A is not correct.

Question 8

The driver side power window will not go up or down. Technician A says a worn motor may be the problem. Technician B says the problem could be caused by a faulty master switch. Who is correct?

Accepted Answer

Either a worn motor or a faulty master switch can cause the power window to not function properly. Therefore, both Technician A and B are correct.

Question 9

An inoperative electrochromic mirror is being discussed. Technician A says the mirror's light sensor may be faulty. Technician B says the external mirror switch may be defective. Who is correct?

Accepted Answer

Technician A's diagnosis of a faulty light sensor is a common cause of inoperative electrochromic mirrors. Technician B's diagnosis of a defective external mirror switch may cause the mirror to move improperly, but would not necessarily affect the electrochromic functionality.

Question 10

The right front electric window is inoperative regardless of which switch is used. It sounds like the motor is turning. Technician A says the window regulator may be disengaged. Technician B says the sector gear may be worn. Who is correct?

Accepted Answer

Both Technician A and B are correct. The sound of the motor indicates that it is working, but the window regulator may be disengaged, meaning the motor is not transferring its power to the window. At the same time, the sector gear may be worn, which will prevent the window from moving up or down even if the motor is working properly. Therefore, both technicians could be right.

Question 11

Horn relays are sometimes included in the horn circuit for which of the following reasons?

Accepted Answer

Horn relays are used to decrease the amount of current that flows through the horn switch, allowing the switch to handle lower current and reducing the risk of switch damage.

Question 12

Blower motor system fan speed control is being discussed. Technician A says this is done by a resistor block wired in parallel to the fan. Technician B says this is done by use by a power module. Who is correct?

Accepted Answer

Both Technician A and Technician B are correct. Fan speed control in blower motor systems can be achieved through a resistor block, which is typically wired in series (not parallel as stated, but the intent seems to imply control mechanism), to provide different speed options by varying resistance. Modern vehicles may use a power module (solid-state controls) to more precisely control fan speed.

Question 13

Technician A says the motor turns faster if there are more armature windings connected between the common and high-speed brushes. Technician B says the less counterelectromotive force (CEMF) in the armature, the greater the armature current. Who is correct?

Accepted Answer

Technician B is correct because less counterelectromotive force (CEMF) in the armature does indeed result in greater armature current, as CEMF opposes the applied voltage, reducing the net voltage and thus the current when it is higher. Technician A's statement is incorrect; more windings between the common and high-speed brushes would increase resistance, not necessarily increase speed.

Question 14

Technician A says a horn that sounds constantly could be caused by a faulty relay. Technician B says a horn that sounds constantly could be caused by an open in the horn button switch. Who is correct?

Accepted Answer

A faulty relay can cause the horn to sound constantly by continuously supplying power to the horn circuit. An open in the horn button switch would prevent the horn from sounding, not cause it to sound constantly.

Question 15

Which component within the wiper motor ensures that when the motor is turned off the wiper arms will be brought to the bottom position?

Accepted Answer

The park switch is the component within the wiper motor that ensures that when the motor is turned off, the wiper arms will be brought to the bottom position. The park switch signals the motor to reverse direction and return to the parked position. Neither the wiper switch nor the recycle relay controls this function.

Question 16

A blower motor that is rotating very slowly is being tested. A voltmeter placed across the power and ground terminals of the motor indicates 6 volts when the blower switch is placed in the "high" speed position. All of the following statements about the possible cause of this problem are true, EXCEPT

Accepted Answer

The voltmeter indicates that there is power getting to the blower motor, which means the power feed circuit and blower relay are likely functioning properly. Excessive ground circuit resistance and a faulty relay would result in no power to the motor. Therefore, the likely cause of the problem is a faulty blower motor.

Question 17

An inoperative electronic cruise control system is being discussed. Technician A says a stuck closed brake switch could be causing the problem. Technician B says the problem could be caused by an open cruise engagement switch. Who is correct?

Accepted Answer

The answer of An inoperative electronic cruise control system is...

Question 18

The rear window defogger is removing only partial areas of fog from the window Technician A says the grid is damaged. Technician B says this indicates a faulty timer circuit. Who is correct?

Accepted Answer

If the grid is damaged, it will not heat up the entire window and could cause partial removal of fog. A faulty timer circuit is not related to the partial removal of fog.

Question 19

The horn of a vehicle equipped with a horn relay is blowing very weakly; its sound level is continuous but low in volume. Technician A says the horn relay contacts may have excessive resistance. Technician B says the horn switch may have high resistance. Who is correct?

Accepted Answer

Technician A is correct because excessive resistance in the horn relay contacts can cause a weak horn sound.

Question 20

An electric window with a two-wire motor operates only in one direction. Which of the following could cause this problem?

Accepted Answer

The answer of An electric window with a two-wire motor...

Quiz 13: Accessorieselectrical Accessories Diagnosis and Repair