ASE L2 Exam Questions

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101.

Technician A states that the scan tool talks directly to the engine control sensors. Technician B states that the scan tool is the most valuable tool when diagnosing vehicle electrical systems.

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

The scan tool communicates directly with the module, not the sensors. The module receives information from the sensors and passes that information to the scan tool.

Scan tools offer information about trouble codes and sensor readings, but a digital multimeter (DMM) provides the best measurement of electrical values.

102.

How many major subsystems are there on a Navistar T444E fuel injection system?

  • Three

  • Two

  • Four

  • Five

Correct answer: Three

There are three major subsystems in a Navistar T444E fuel injection system. The fuel supply system is responsible for delivering fuel to the injectors.

The injector control system sends high-pressure lubricating oil to the injectors. The fuel injectors use the oil to pressurize the fuel and deliver it to the combustion chambers.

103.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that the intake grid heater is designed to warm the intake air box in cold weather. Technician B states that the intake grid heater is used to warm the intake manifold in cold weather.

Who is correct?

  • Technician B

  • Technician A

  • Both A and B

  • Neither A nor B

Correct answer: Technician B

The intake grid heater is supplied with battery voltage from the relay. It is designed to warm the manifold air to assist the engine starting in colder temperatures.

The current draw of the intake grid heater is 170A ± 10A.

104.

Typically a glow plug will draw about how many amps?

  • 10

  • 30

  • 60

  • 80

Correct answer: 10

A typical glow plug will draw about 10 amps. In comparison, the air inlet heater may draw about 80 amps.

Because these devices tend to fail open, malfunctioning air inlet heaters and glow plugs tend to have no current draw.

105.

Sensors fall into all of the following categories, except:

  • Capacitors

  • Switches

  • Resistors

  • Signal generators

Correct answer: Capacitors

Sensors fall into three categories: switches, resistors, and signal generators. Sensors are not capacitors.

Switches open or close a circuit, while resistors restrict the flow of current. The signal generator creates a repeating or non-repeating waveform.

106.

Technician A states that the barometric pressure sensor isn't connected to the 5-volt reference, but is connected to the sensor ground. Technician B states that the turbo boost pressure sensor is connected to the 5-volt reference and the sensor ground.

Who is correct?

  • Technician B

  • Technician A

  • Both A and B

  • Neither A nor B

Correct answer: Technician B

The turbo boost pressure sensor, barometric pressure sensor, and oil pressure sensor are connected to both the 5-volt reference and the sensor ground.

107.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that the engine coolant temperature sensor is located on the driver's side of the engine block. Technician B states that the engine coolant temperature sensor is located on the passenger's side of the block.

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

Technician A and B are both incorrect, because the engine coolant temperature sensor isn't located in the block. It's found in the cylinder head.

The engine coolant sensor is found near the coolant thermostats, and it sends a signal to the ECM that's used for fuel management, cooling fan operation, DPF regeneration, engine protection, and the instrument cluster temperature gauge.

108.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that the engine protection override switch is wired to the ECM. Technician B states that the engine protection override switch is wired to the BCM.

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

The engine protection override switch is a two-wire switch that is connected to the ECM, making technician A correct. This switch is usually open, but closes during a warning shutdown period when a 30-second delay is requested.

The engine protection override switch is not connected to the BCM.

109.

What is the normal maximum air inlet specification?

  • 25 inches of water

  • 10 inches of water

  • 5 inches of water

  • 40 inches of water

Correct answer: 25 inches of water

Air intake restriction tests are done with either an electronic vacuum gauge or a water manometer to read inches of water. The normal maximum air inlet specification is 25 inches of water.

All tests should be performed with the engine under full load.

110.

Using the composite vehicle on the ASE website, answer the following question:

How many amps is the alternator/generator rated at?

  • 200 amps

  • 150 amps

  • 175 amps

  • 225 amps

Correct answer: 200 amps

The alternator/generator is a 200-amp, internally regulated alternator equipped with remote sense.

The target voltage for the alternator/generator is 14.1 VDC (± 0.5 VDC).

111.

Using the composite vehicle on the ASE website, answer the following question:

Where is the DEF pressure sensor located?

  • DEF pressure line

  • DEF return line

  • DEF pump

  • DEF doser valve

Correct answer: DEF pressure line

The DEF pressure sensor is located in the DEF pressure line. The sensor sends information to the ECM regarding the pressure.

The ECM takes this signal to determine the pressure going into the DEF doser valve, measuring voltages between 0.50 to 4.50.

112.

What is the maximum allowable backpressure reading on most engines?

  • 1 PSI

  • 2 PSI

  • 3 PSI

  • 4 PSI

Correct answer: 1 PSI

1 PSI is usually the maximum backpressure reading. Some engines have a maximum reading of less than 1 PSI at full rated speed.

Many DPFs will cause the CEL when there's a difference in pressure at the two ends.

113.

All of the following statements are true about an output that can be energized by a scan tool, except:

  • The output device is faulty

  • The output device is operable

  • The ECM can operate the output device

  • All connections to the output device are intact

Correct answer: The output device is faulty

If the scanner can be used to energize an output device, the device is operable and doesn't need to be replaced. This method also proves that the ECM can operate the device.

All connections to the output device are intact and further diagnosis is needed to figure out the cause of the faults.

114.

Technician A states that low ECM supply voltage could cause the ECM to not communicate with the diagnostic tool when evaluating a no-start situation where the engine cranks. Technician B states that the problem could be a malfunctioning data link connector.

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

Technician A is correct because low voltage supply can cause the ECM to shut down. If this occurred, the ECM wouldn't operate the injectors or communicate with the scanner.

A malfunctioning data link connector may stop the scanner from communicating with the ECM, but it wouldn't cause a no-start condition.

115.

Technician A states that tampering with original equipment emission control systems is legal but not recommended. Technician B states that it is illegal to tamper with original equipment emission control systems.

Who is correct?

  • Technician B

  • Technician A

  • Neither A nor B

  • Both A and B

Correct answer: Technician B

It is illegal to tamper with emission control systems on a vehicle. It's also illegal to modify or remove any original equipment emission control systems.

If equipment is missing or modified, it must be replaced or repaired to match with the original equipment.

116.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that the fuel pressure control solenoid defaults open with the key off. Technician B states that the fuel volume control solenoid defaults closed with the key off.

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

The fuel pressure control solenoid defaults closed with the key off, making technician A incorrect. This solenoid is mounted to the fuel rail that returns the fuel to the tank.

The fuel volume control solenoid defaults open with the key off, making technician B incorrect. This solenoid is mounted to the pump.

117.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that the fuel pressure control solenoid is mounted on the fuel return rail to the tank. Technician B states that the fuel pressure control solenoid is mounted to the pump.

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

The fuel pressure control solenoid is mounted to the fuel rail that returns fuel from the fuel rail to the tank. This solenoid works with the fuel volume control solenoid to ensure the correct amount of fuel pressure.

With the key OFF, this solenoid defaults to a closed position. It holds 5000 PSI for 30 seconds after the key is turned off.

118.

In what year were all light-duty diesel engines required to use diesel exhaust particulate filters?

  • 2007

  • 2005

  • 2009

  • 2010

Correct answer: 2007

Since 2007, all light-duty diesel engines have been required to use DPF systems to meet emission requirements. The diesel oxidation catalysts (DOCs) have also been used in all light-duty diesel trucks since 2007.

These systems were added to cut down on emissions and to meet federal standards.

119.

Technician A states that all transmission manufacturers allow stall tests. Technician B states that the limit of a stall test is no longer than 20 seconds.

Who is correct?

  • Neither A nor B

  • Technician A

  • Technician B

  • Both A and B

Correct answer: Neither A nor B

A stall test is helpful for distinguishing between an engine defect and transmission/driveline problems. Before performing a stall test, the technician should check to make sure the manufacturer allows it.

All stall tests should be limited to 10 seconds or less. Otherwise, damage may occur.

120.

Using the composite vehicle on the ASE website, answer the following question:

Technician A states that if the EGR valve loses communication with the ECM, the valve will default to the closed position. Technician B states that if the EGR valve loses communication with the ECM, the valve defaults to the open position.

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

Power and ground is supplied to the EGR over the private CAN network. If communication with the ECM is lost, the valve will default to the closed position, making technician A correct.

If power becomes interrupted to the valve, the position remains where it currently is.