ASE L1 Exam Questions

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61.

A vehicle has the following I/M results at idle: 250 ppm HC, 3% CO, 9% CO2, and 0.2% O2. Which of the following is the MOST likely cause?

  • A leaking fuel injector

  • A low map sensor voltage

  • A faulty idle air control valve

  • A restricted fuel filter 

Correct answer: A leaking fuel injector

These I/M results indicate a rich condition, which could be caused by leaking fuel injectors. When a rich condition is present, the map sensor voltage will be high. A restricted fuel filter leads to a lean condition, and a faulty idle air control valve usually leads to stalling and fluctuating idle speeds.

62.

The MAP sensor voltage on the composite vehicle reads 2.5 volts. This indicates a manifold vacuum of which of the following?

  • 12 in. Hg

  • 15 in. Hg

  • 18 in. Hg

  • 21 in. Hg

Correct answer: 12 in. Hg

Looking at the MAP sensor chart for the composite vehicle, a sensor voltage reading of 2.5 volts indicates that manifold pressure is 60.7 kPa and vacuum is 12 in. Hg.

15 in. Hg correlates to 50.5 kPa and a sensor voltage of 2.00 volts. 18 in. Hg is 40.4 kPa and 1.50 volts, while 21 in. Hg shows 30.2 kPa and 1.00 volt. 

63.

What is the normal AFRS heater resistance of a composite vehicle at 68 °F (20 °C)?

  • 2-6 Ω

  • 1-5 Ω

  • 3-7 Ω

  • 4-8 Ω

Correct answer: 2-6 Ω

With a composite vehicle, the normal AFRS heater resistance is 2-6 Ω at 68 °F (20 °C).

64.

The composite vehicle is producing excessive hydrocarbons. Technician A says a blown #4 fuse could be the cause. Technician B says an open CKP sensor could be the cause. 

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

Both technicians are wrong. An open crankshaft position (CKP) sensor would prevent the engine from starting.

Fuse #4 of the composite vehicle sends power to all six coils, preventing the vehicle from running if it is blown. 

65.

What maximum value is given to define a small EVAP system leak?

  • 0.020 inches

  • 0.010 inches

  • 0.030 inches

  • 0.040 inches

Correct answer: 0.020 inches

Natural vacuum leak detection finds small EVAP system leaks of up to 0.020 inches (0.5 mm). A large vacuum leak of 0.040 inches (1.0 mm) is detected with vacuum decay. 

66.

All the following are part of the secondary ignition circuit EXCEPT:

  • Triggering mechanism

  • Secondary coil windings

  • Spark plugs 

  • Spark plug wires 

Correct answer: Triggering mechanism

The primary portion of the ignition system consists of the low voltage components, including the battery, ignition switch, primary coil windings and triggering mechanism (crankshaft position sensor), and switching device. 

The secondary portion of the ignition system consists of the high-voltage components, including the secondary coil windings, spark plug wires, and spark plugs. 

67.

For proper operation, the ECM must receive a regulated voltage between what values?

  • 12 and 14 volts

  • 8 and 10 volts

  • 10 and 12 volts

  • 14 and 16 volts

Correct answer: 12 and 14 volts.

The charging system must provide a regulated 12 to 14 volts to the ECM for it to operate properly. Without the proper voltage, many strange symptoms can occur. 

68.

CAN Low (L) has a dormant voltage of which of the following?

  • 11 volts

  • 0.65 volts 

  • 0.25 volts 

  • 4.65 volts 

Correct answer: 11 volts

CAN Low (L) has a dormant voltage of 11 volts that decreases to 4.65 volts when communicating. 

CAN High (H) has a dormant voltage of 0.25 volts that increases to 0.65 volts when communicating. 

69.

The composite vehicle is being discussed. Technician A says the crankshaft position sensor should produce a square waveform pattern. Technician B says the camshaft position sensor should produce a sawtooth waveform pattern. 

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

Looking at the information for the composite vehicle, the camshaft sensors are Hall-effect sensors, which produce a square waveform pattern. The crankshaft sensor is a permanent magnet sensor, which produces a sawtooth waveform pattern. 

70.

Technician A says a failed catalytic converter can result in a vehicle that won't start. Technician B says a failed catalytic converter can result in a lack of power. 

Who is correct?

  • Both A and B

  • Technician A

  • Technician B

  • Neither A nor B

Correct answer: Both A and B

Both technicians are correct. A failed catalytic converter can put excessive back pressure on the engine, resulting in a vehicle that doesn't start or lacks power. 

A clogged converter can also lead to hard starting. If there's a broken monolith, there could be knocking or rattling sounds. 

71.

The typical "light-off" temperature of a catalytic converter is AT LEAST what value? 

  • 400 degrees Fahrenheit

  • 200 degrees Fahrenheit

  • 300 degrees Fahrenheit

  • 500 degrees Fahrenheit

Correct answer: 400 degrees Fahrenheit

For the catalytic converter to work properly and reduce emissions, it must be at a temperature of at least 400 degrees. At this temperature, the chemical reaction inside the converter can take place. 

72.

Technician A states that pins 4 and 16 provide power to the OBD II scan tool. Technician B states eight diagnostic link connector (DLC) cavities are common across all vehicles, with the other eight remaining manufacturer-specific. 

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

Technician A is correct. Pin 4 on the OBD II connector is ground, and 16 is B+, supplying power to the scan tool, so an external power supply isn't needed.

Technician B is incorrect. Seven of the DLC cavities are common, with the other nine remaining manufacturer-specific. 

73.

Based on the composite vehicle, what does the engine temperature need to reach to complete a warm-up cycle?

  • 160 degrees Fahrenheit

  • 220 degrees Fahrenheit

  • 180 degrees Fahrenheit

  • 200 degrees Fahrenheit

Correct answer: 160 degrees Fahrenheit

For the composite vehicle to complete a warm-up cycle, the engine temperature must reach 160 degrees Fahrenheit. There must also be a 40-degree increase. 

The ECM and TCM use the warm-up cycle to clear the freeze frame data and DTCs automatically.

74.

Which of the following may increase as a result of a leaking EGR valve?

  • HC

  • CO

  • CO2

  • NOx

Correct answer: HC

Hydrocarbon (HC) increases as a result of incomplete combustion. A leaking exhaust gas recirculation (EGR) valve can cause a misfire, resulting in increased HC. All the other options would result in a slight decrease in emissions level or no change at all. 

If the EGR valve is stuck or the passages are clogged, increased combustion temperatures will create higher NOx emissions. 

75.

A signal from which of the following is used to determine whether the engine control system is in a closed loop?

  • Oxygen sensor 

  • Coolant temperature sensor

  • Camshaft position sensor

  • Crankshaft position sensor 

Correct answer: Oxygen sensor

Once the vehicle has reached a closed loop, the ECM will start receiving and using the signal from the oxygen (O2) sensor for fuel control. 

The coolant temperature sensor, camshaft position sensor, and crankshaft position sensor aren't used to determine whether the engine control system is in a closed loop. 

76.

Technician A says in a waste spark system, the ignition components from two companion cylinders form a series circuit. Technician B says in a waste spark system, the cylinder that is on the compression stroke is referred to as the "waste" cylinder. 

Who is correct?

  • Technician A

  • Neither A nor B

  • Technician B

  • Both A and B

Correct answer: Technician

Technician A is correct. In a waste spark system, the ignition components from two companion cylinders form a series circuit, not a parallel circuit. 

Technician B is incorrect. The cylinder that is on the compression stroke is referred to as the "event" cylinder, whereas the cylinder that is on the exhaust stroke is referred to as the "waste" cylinder. 

77.

Technician A says an ohmmeter is the best way to evaluate an electrical circuit's condition. Technician B says a circuit is best tested for excessive energy loss using an ammeter. 

Who is correct? 

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

Both technicians are wrong. The best way to check for excessive circuit energy loss (voltage loss) is by performing a voltage drop test using a voltmeter.

Technicians commonly use an ohmmeter mistakenly to check the condition of an electrical circuit. An ohm reading can come back normal from a cable with just one strand of wire intact because the ohmmeter sends just a few milliamps of current through the circuit for testing. 

78.

A vehicle failed the I/M test for excessive NOx during acceleration. Technician A says the most likely cause is carbon buildup inside the engine. Technician B says the most likely cause is a failed water pump. 

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

Both technicians are wrong. While carbon buildup or a failing water pump are both potential causes of excessive oxides of nitrogen (NOx) emissions, in this case, they are not the most likely cause. A faulty exhaust gas recirculation (EGR) valve is the most likely cause of a vehicle with excessive NOx emissions during acceleration.

79.

Technician A says an injector balance test can pinpoint a faulty fuel injector. Technician B says defective fuel injectors can cause a no-start condition. 

Who is correct?

  • Both A and B

  • Technician A

  • Technician B

  • Neither A nor B

Correct answer: Both A and B

Both technicians are correct. Defective fuel injectors can cause a misfire or a no-start condition. A balance test allows faulty injectors to be pinpointed. 

Before beginning an injector balance test, allow the engine to cool completely, or vapor bubbles in the fuel rail can return misleading results. 

80.

Technicians are discussing the composite vehicle. Technician A says if the “valid key” message doesn't get to the ECM within two seconds of engine startup, the fuel injectors will be automatically disabled. Technician B says the immobilizer control module cannot prevent starter motor operation for anti-theft purposes. 

Who is correct?

  • Both A and B

  • Technician A

  • Technician B

  • Neither A nor B

Correct answer: Both A and B

Both technicians are correct. When a valid key isn't used or the message doesn't get to the ECM within two seconds of the engine starting, power is cut off to the fuel injectors and the engine will stall.

The immobilizer control module, ECM, and TCM cannot prevent the starter from operating in order to stop theft.