Question 1

A technician is measuring the voltage drop across a load in a series circuit while the circuit is active. If the source voltage is

12.6 V

and the digital multimeter displays a reading of

0.5 V

across the ground side of the circuit, which of the following is most likely true?

Accepted Answer

There is excessive resistance in the ground circuit.

Answer

The circuit is operating within normal specifications.

Answer

The load has internal short-to-ground.

Answer

The battery is discharged below its capacity.

Question 2

Two technicians are discussing a series circuit containing two identical light bulbs. Technician A says that if one bulb burns out, the other bulb will remain illuminated. Technician B says that according to Kirchhoff's Voltage Law, the sum of the voltage drops across both bulbs must equal the source voltage. Who is correct?

Accepted Answer

Technician B only

Answer

Both Technician A and Technician B

Answer

Neither Technician A nor Technician B

Answer

Technician A only

Question 3

An automotive technician is using an ammeter to diagnose a parasitic draw on a vehicle battery. If the meter is connected in parallel with the battery and the circuit is energized, which of the following is the most likely outcome?

Accepted Answer

The internal fuse of the ammeter will blow due to excessive current flow.

Answer

The battery voltage will increase to compensate for the meter's internal resistance.

Answer

The meter will accurately measure the current draw of all components.

Answer

The meter will display the total resistance of the vehicle's electrical system.

Question 4

An automotive technician is measuring the resistance of a fuel injector using a digital multimeter. The specification is

12.6 V

to

0.5 V

. If the multimeter is set to the

2k \Omega

scale and displays a value of

0.014

, which of the following is the most appropriate action?

Accepted Answer

The injector is within specifications; no further action is required for this component.

Answer

Replace the injector because

12.6 V

is below the minimum resistance.

Answer

Perform a voltage drop test because the resistance is infinitely high.

Answer

Switch the meter to the DC Voltage setting to verify the measurement.

Question 5

Technician A says that a digital multimeter (DMM) with high input impedance should be used when testing electronic control module (ECM) circuits to prevent drawing excessive current. Technician B says that an analog voltmeter is preferred for these tests because it places a larger load on the circuit, providing a more 'real-world' measurement. Who is correct?

Accepted Answer

Technician A only

Answer

Both Technician A and Technician B

Answer

Technician B only

Answer

Neither Technician A nor Technician B

Question 6

An automotive blower motor circuit is being tested because the motor only operates on high speed. If the system uses a resistor pack to control the lower speeds, what is the most likely cause of the failure?

Accepted Answer

The thermal fuse or the resistor coils within the resistor pack are open.

Answer

The blower motor relay is stuck in the closed position.

Answer

The blower motor has an internal short circuit in its windings.

Answer

The ground connection for the high-speed circuit is disconnected.

Question 7

A technician is performing a voltage drop test on a starter motor's positive cable during cranking. The battery voltage is

12.6 V

during cranking, and the voltmeter connected between the battery positive post and the starter solenoid input terminal reads

0.5 V

. Which of the following is the most likely conclusion?

Accepted Answer

There is excessive resistance in the positive battery cable or its connections.

Answer

The starter motor is drawing too much current.

Answer

The reading is normal, as voltage drop should be approximately

12.6 V

of the source.

Answer

The battery is defective and should be replaced.

Question 8

An automotive technician is diagnosing a parasitic draw on a vehicle with a

12.6 V

battery. After turning off all accessories and waiting for the modules to enter sleep mode, the ammeter reads

0.5 V

. Which of the following is the most likely conclusion based on standard industry specifications?

Accepted Answer

The current draw is excessive; a typical parasitic drain should be less than

12.6 V

.

Answer

The battery voltage is too low to perform a valid parasitic draw test; it must be at least

12.6 V

.

Answer

The current draw is normal; most modern vehicles pull between

12.6 V

and

0.5 V

at rest.

Answer

The reading indicates a dead short to ground in the primary starter cable.

Question 9

Technician A says that a digital multimeter (DMM) should be set to the Ohms setting to check for continuity across a blown fuse while it is still powered in the circuit. Technician B says that a voltage drop test across a fuse can be used to identify current flow without removing the fuse. Who is correct?

Accepted Answer

Technician B only

Answer

Neither Technician A nor Technician B

Answer

Both Technician A and Technician B

Answer

Technician A only

Question 10

A technician is measuring a blower motor circuit using a voltmeter. With the motor turned on, the voltmeter reveals a

12.6 V

drop on the ground side of the motor connector. What does this measurement indicate?

Accepted Answer

There is excessive resistance in the ground circuit path.

Answer

The battery is overcharging and providing too much voltage.

Answer

The motor is operating efficiently with minimal resistance.

Answer

The motor has an internal short circuit to the casing.

Question 11

An automotive technician is using a Digital Multimeter (DMM) to test a relay. With the relay energized, the technician measures the resistance across the closed load contacts (terminals 30 and 87) and finds a reading of

12.6 V

. What does this result indicate?

Accepted Answer

The relay contacts have excessive resistance and the relay should be replaced.

Answer

The relay is functioning perfectly for a high-current circuit.

Answer

The control coil is partially shorted, drawing too much current.

Answer

The circuit is operating within the standard tolerance for automotive relays.

Question 12

While diagnosing a dim headlight concern, a technician measures

12.6 V

at the battery terminals and

0.5 V

at the headlight connector while the circuit is turned on. What is the calculated voltage drop for this circuit and what does it suggest?

Accepted Answer

The voltage drop is

12.6 V

, suggesting excessive resistance in the power-side wiring or connections.

Answer

The voltage drop is

12.6 V

, suggesting the battery is sulfated and cannot hold a load.

Answer

The voltage drop is

12.6 V

, suggesting the circuit is within normal operating parameters.

Answer

The voltage drop is

12.6 V

, suggesting a short circuit to ground.

Question 13

A technician is testing a 12V automotive circuit with a single load. If the circuit's total resistance is measured at

12.6 V

, what is the expected current flow, and which tool is best suited to verify this while the circuit is active without breaking the wire?

Accepted Answer

3A

, measured using an inductive DC amp clamp.

Answer

3A

, measured using an ohmmeter in series.

Answer

3A

, measured using a high-impedance voltmeter.

Answer

3A

, measured using a test light connected to ground.

Question 14

A technician is using a digital multimeter to measure the duty cycle of a Pulse Width Modulated (PWM) EGR solenoid. If the meter displays a duty cycle of

12.6 V

on a 'Ground-Side Controlled' circuit, what does this indicate about the solenoid's 'On' time relative to its 'Off' time?

Accepted Answer

The solenoid is energized and grounded for

12.6 V

of the total cycle time.

Answer

The solenoid is receiving

12.6 V

continuously instead of

0.5 V

.

Answer

The solenoid is inactive because duty cycles below

12.6 V

cannot overcome spring tension.

Answer

The circuit is open for

12.6 V

of the cycle, meaning the solenoid is active for most of the time.

Question 15

An automotive technician is performing a battery load test on a

12.6 V

battery with a Cold Cranking Amps (CCA) rating of

0.5 V

. After applying a load of

2k \Omega

for 15 seconds, the voltage drops to

0.014

at a temperature of

70^{\circ}F

. What is the most appropriate diagnosis?

Accepted Answer

The battery failed the load test and should be recharged and retested or replaced.

Answer

The battery is overcharged, causing the internal resistance to drop the voltage.

Answer

The battery passed the load test because the voltage remained above

12.6 V

.

Answer

The load applied was incorrect; the test should be performed at

12.6 V

for 30 seconds.

Question 16

An automotive technician is using an ammeter to measure current in a series circuit containing a

12.6 V

battery and a lamp with a resistance of

0.5 V

. If the technician uses Ohm's Law to calculate the expected current, what should the meter display?

Accepted Answer

Answer

Answer

Answer

Question 17

Two technicians are discussing a circuit with two

12.6 V

resistors connected in parallel. Technician A says the total resistance of the circuit is

0.5 V

. Technician B says the total resistance is

2k \Omega

. Who is correct?

Accepted Answer

Technician B only

Answer

Both Technician A and Technician B

Answer

Technician A only

Answer

Neither Technician A nor Technician B

Question 18

Technician A says that when measuring resistance with an ohmmeter, the circuit should be powered to ensure the most accurate reading. Technician B says that an ohmmeter uses its own internal battery to send a small current through the component being tested. Who is correct?

Accepted Answer

Technician B only

Answer

Both Technician A and Technician B

Answer

Neither Technician A nor Technician B

Answer

Technician A only

Question 19

A technician is diagnosing an interior light circuit where the fuse blows as soon as it is replaced, even when the light switch is in the 'OFF' position. What does this condition most likely indicate?

Accepted Answer

A short to ground between the fuse and the switch.

Answer

A high resistance connection at the bulb socket.

Answer

An open circuit caused by a broken wire.

Answer

A short to ground after the light switch in the circuit.

Question 20

A technician is testing a coolant temperature sensor, which is a Negative Temperature Coefficient (NTC) thermistor. If the technician measures the resistance of the sensor while the engine is warming up, what should happen to the ohmmeter reading?

Accepted Answer

The resistance should decrease as the temperature increases.

Answer

The resistance should decrease until the thermostat opens, then rapidly increase.

Answer

The resistance should remain constant at

12.6 V

.

Answer

The resistance should increase as the temperature increases.

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