ASE L1 Exam Questions

Page 7 of 10

121.

The composite vehicle is being discussed. Technician A says the coils are controlled by drivers inside the ECM. Technician B says the ECM supplies power to the coils. 

Who is correct? 

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

Only technician A is correct. The coils are controlled by drivers inside the engine control module (ECM) that switch the path to ground on and off. The ECM also controls the ignition timing. 

Technician B is incorrect because the power source comes from fuse #4. The ECM is only responsible for grounding the coils. 

122.

Which of the following is LEAST likely to cause intermittent vacuum fluctuations of 3 to 4 in. Hg?

  • Sticking valves

  • Restricted exhaust system

  • Improper spark plug gap

  • Bad ignition coil 

Correct answer: Sticking valves

Sticking valves cause an intermittent fluctuation of the gauge needle from 3 to 4 in. Hg. Improper spark plug gap, a bad ignition coil, and other ignition problems can lead to a fluctuation between 1 and 2 in. Hg.

A restricted exhaust system would lead to a steady drop in vacuum with rpm increasing. 

123.

All the following are true regarding the I/M 240 test EXCEPT:

  • The results are indicated in grams per second.

  • It is the most accurate indication of a vehicle's emissions.

  • It includes a braking portion. 

  • A graph printout is provided at the end of the test.

Correct answer: The results are indicated in grams per second.

The I/M 240 test measures emissions under various driving conditions and uses constant volume sampling to maintain a steady gas flow. Results are indicated in grams per mile, not grams per second. 

All the other options are true.

124.

A three-way catalytic converter is used to reduce which of the following?

  • HC, CO, and NOx

  • HC, CO, and CO2

  • HC, O2, and NOx

  • O2, CO2, and NOx

Correct answer: HC, CO, and NOx

Catalytic converters perform chemical reactions to reduce emissions. A three-way converter is used to reduce HC, CO, and NOx emissions. 

CO2 is a sign of efficient combustion and doesn't need to be reduced. 

125.

All the following modules on the composite vehicle support communication with a scan tool and allow output control of components EXCEPT:

  • BCM

  • ECM

  • TCM

  • Instrument cluster 

Correct answer: BCM

On the composite vehicle, the engine control module (ECM), transmission control module (TCM), and instrument cluster have software that supports functional testing. 

The scan tool can be used for output control of components. This can be done using a scan tool connected to the OBD port.

126.

The ignition waveform pattern for a vehicle shows the sparklines for all cylinders sloping upward. Which of the following is the MOST likely cause?

  • Excessive EGR

  • A bad spark plug wire

  • A worn spark plug

  • A bad fuel injector

Correct answer: Excessive EGR

The sparkline will slope upward as a result of high resistance from a lean air/fuel mixture or excessive exhaust gas recirculation (EGR). If all the cylinders show sparklines that slope upward, the cause is something common to all cylinders.

The other issues should only affect certain cylinders, not all of them.  

127.

During a snap throttle test, how much higher can the vacuum increase with piston rings that are sealing correctly?

  • Up to 5 in. Hg

  • Up to 3 in. Hg

  • Up to 7 in. Hg

  • No rise

Correct answer: Up to 5 in. Hg

With piston rings sealing correctly, the vacuum can rise by up to 5 in. Hg during a snap throttle test. If it doesn't, the reading could indicate bad piston rings. 

128.

All the following are symbols or words used for the malfunction indicator light, EXCEPT:

  • Wrench symbol

  • Check engine soon

  • Service engine soon

  • ISO engine symbol

Correct answer: Wrench symbol

Depending on the manufacturer and vehicle, the MIL could be the "check engine soon," "service engine soon," or ISO engine symbol. 

Some manufacturers use the wrench symbol to indicate when it's time for maintenance. 

129.

Technician A says NOx emissions are checked during a two-speed idle emissions test. Technician B says HC emissions are checked during a two-speed idle emissions test. 

Who is correct?

  • Technician B

  • Technician A

  • Both A and B

  • Neither A nor B

Correct answer: Technician B

Only technician B is correct. The two-speed idle test is a non-load test used to check hydrocarbon (HC) and carbon monoxide (CO) emissions. It is not used to check oxides of nitrogen (NOx) emissions. 

The two-speed idle test is done with a four-gas analyzer that registers HC, CO, CO2, and O2. 

130.

On the composite vehicle, how many warmup cycles without the fault reoccurring is the freeze frame automatically cleared? 

  • 40

  • 3

  • 20

  • 12

Correct answer: 40

If the vehicle completes 40 warmup cycles without the same fault recurring, the DTC and freeze frame are automatically cleared from the ECM/TCM memory.

After three consecutive passing trips, the MIL will turn off, but the DTC and freeze frame data will remain. 

131.

Technician A says a faulty EGR valve can cause increased HC emissions. Technician B says a faulty EGR valve can cause increased NOx emissions. 

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. An exhaust gas recirculation (EGR) valve that won't close properly can result in an engine misfire and increased emissions. An EGR valve that is stuck closed or clogged passages can result in increased combustion temperatures and NOx emissions. 

132.

The EVAP canister purge solenoid is enabled on the composite vehicle when the coolant temperature reaches what value? 

  • 150 degrees Fahrenheit 

  • 200 degrees Fahrenheit 

  • 120 degrees Fahrenheit 

  • 210 degrees Fahrenheit 

Correct answer: 150 degrees Fahrenheit 

The evaporative emissions (EVAP) canister purge solenoid is used to regulate purge vapor flow into the intake manifold. On the composite vehicle, the solenoid is enabled when engine coolant reaches a temperature of 150 degrees Fahrenheit (66 degrees Celsius). 

133.

A saturated switch fuel injector waveform pattern is being analyzed. The amplitude of the inductive spike is far less than expected. This could cause which of the following?

  • A lean air/fuel mixture

  • A rich air/fuel mixture 

  • Engine running below operating temperature

  • Overheating engine

Correct answer: A lean air/fuel mixture

If the amplitude of the inductive spike is far less than expected, the coil windings are probably shorted, resulting in a lean air/fuel mixture. Inductive spikes have no relation to the engine operating conditions.

134.

The A/C compressor clutch will not engage on the composite vehicle. Which of the following is the MOST likely cause?

  • An open circuit at ECM pin 40

  • An open circuit at ECM pin 10

  • A blown fuse #2

  • A short to ground at ECM pin 9

Correct answer: An open circuit at ECM pin 40

Engine control module (ECM) pin 40 is the A/C pressure sensor input pin to the ECM. An open circuit here would cause the ECM to read a false high-voltage signal and assume the A/C pressure is above 450 psi. As a result, the ECM would disable A/C compressor operation. 

An open circuit at ECM pin 10 is going to keep the fan from running, while a blown fuse #2 affects the keep-alive memory. A short to ground at ECM pin 9 keeps the A/C clutch relay on at all times. 

135.

Which of the following is the MOST likely cause of the composite vehicle cranking but not starting? 

  • A blown fuse #4 

  • An open at ECM pin 19

  • A failed #1 coil 

  • A fouled #5 spark plug

Correct answer: A blown fuse #4

Fuse #4 supplies power to all of the coils and injectors. If it was blown, the vehicle would crank but would not start. 

ECM pin 19 grounds coil #6. This and the other options would allow the vehicle to start but would result in a misfire.

136.

All the following are true regarding the accelerated simulation model (ASM) emissions test EXCEPT: 

  • It is an unloaded test.

  • It checks for hydrocarbons. 

  • The vehicle is tested on a dynamometer. 

  • The most common ASM tests are the 5015 and the 2525.

Correct answer: It is an unloaded test.

The Acceleration Simulation Mode (ASM) test is a loaded emissions test in which the vehicle is checked for hydrocarbons, carbon monoxide, and oxides of nitrogen. 

All the other options are true. 

137.

The composite vehicle has a misfire. Which of the following could be the cause?

  • An open circuit at ECM pin 16

  • An open circuit at ECM pin 25

  • A blown fuse #2 

  • An open circuit at ECM pin 42

Correct answer: An open circuit at ECM pin 16

A misfire indicates a problem with the secondary ignition system. An opening at ECM pin 16 would prevent ignition coil #5 from operating, leading to a misfiring condition.

ECM pin 25 runs to throttle position sensor 2. If there's an open circuit, performance problems are likely, but not misfiring. Fuse #2 sends power to the Keep Alive Memory, which won't lead to any performance issues if the fuse is blown. ECM pin 42 is for the fuel level sensor, so an open circuit would only cause erroneous readings of the fuel gauge.

138.

Technicians are discussing the composite vehicle. Technician A states when the electronic throttle control system enters limp-in operation, idle speed ranges from 1400 to 1500 rpm. Technician B states after the electronic throttle control system component replacement, an idle relearn procedure is necessary. 

Who is correct?

  • Technician A

  • Technician B

  • Both A and B

  • Neither A nor B

Correct answer: Technician A

Only technician A is correct. When the electronic throttle control system goes into limp-in mode, the idle speed will range from 1400 to 1500 rpm. The spring-loaded throttle plate will also return to the default position of 15% opening, and the corresponding TAC value indicates 15% on a scan tool.

Technician B is incorrect. There's no idle relearn procedure needed after replacing a component of the electronic throttle control system. 

139.

When analyzing the ignition waveform pattern of a vehicle equipped with a waste spark ignition system, there is more than a 20% variation in firing kV between half of the cylinders. Technician A says this indicates an open spark plug wire. Technician B says this indicates an incorrect air/fuel ratio. 

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. It is normal to notice more than a 20% discrepancy between the firing voltage when analyzing a waste spark system. This is because the plugs in the negative cylinders require greater energy than those in the positive cylinders. 

If there's more than a 20% discrepancy between the firing voltage in a traditional ignition system, the reading indicates a problem with the particular cylinder. 

140.

While testing the composite vehicle's variable valve lift motors, what should the scan tool value read under normal conditions?

  • 0.5 to 4.5 V

  • 0.0 to 3.5 V

  • 0.5 to 5.5 V 

  • 0.0 to 6.5 V

Correct answer: 0.5 to 4.5 V

During a test of the variable valve lift motors on the composite vehicle, the scan tool value reading should be between 0.5 V (0%) and 4.5 V (100%). 

0.5 volts is measured at minimum lift with 4.5 volts reading at full valve lift.