Deck 14: Diesel Engine Electronics

Question 1

The current flow through an inductor cannot instantly change from one level to another. However, the voltage measured across an inductor can instantly change from one level to another.

Answer 1

True

Question 2

An in-range failure always results in a DTC being set.

Answer 2

False

Question 3

In a closed-loop control system, error = desired output - measured output.

Answer 3

True

Question 4

Exhaust gas recirculation (EGR) is used to reduce particulate matter (PM) exhaust emissions.

Question 5

A spark plug and ignition coil is typically used in an SCR system to cause the DEF to ignite.

Question 6

The injection control pressure (ICP) of a HEUI fuel system is controlled by which device?

A) Fuel pump inlet valve
B) H-bridge
C) ICP sensor
D) Injection pressure regulator (IPR)

Question 7

Technician A says that cam-actuated unit injectors use a common high pressure pump to develop injection pressures. Technician B says that a single-actuator EUI typically has two electrical terminals. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 8

Which of the following failures would most likely illuminate the MIL lamp?

A) Low engine oil pressure
B) Low engine coolant level
C) Disconnected DEF dosing injector connector
D) All of the above would likely illuminate the MIL lamp.

Question 9

Technician A says that a pending DTC always results in a confirmed DTC. Technician B says that an electronic service tool can be used to clear a permanent DTC. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 10

Technician A says that the best way to check for a misfiring cylinder on a high-pressure common rail fuel system is to crack each injector line open one by one. Technician B says that it may be necessary to use an electronic service tool to enter new injector calibration information into the ECM memory if an injector is replaced. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 11

A 2007 diesel engine with a DOC and DPF has an internal problem with cylinder 2 which causes insufficient compression for ignition. What might be a likely indication of this failure other than an engine performance complaint?

A) Black exhaust smoke out of the exhaust stack
B) The DOC outlet temperature is substantially higher than the DOC inlet temperature when DPF regeneration is not being performed.
C) The exhaust smells like ammonia.
D) The SCR catalyst is very hot.

Question 12

Technician A says that a variable geometry turbocharger (VGT) may be used to regulate EGR flow. Technician B says that a smart actuator may be used to control the position of a variable geometry turbocharger. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 13

Which of the following would be considered to be a type of in-cylinder exhaust emissions reduction?

A) In-cylinder dosing of DEF
B) Selective catalytic reduction (SCR)
C) Exhaust gas recirculation (EGR)
D) Exhaust aftertreatment

Question 14

Technician A says that the ECM may determine the amount of soot in the DPF by measuring the differential pressure across the DPF. Technician B says that the ECM may calculate or estimate the amount of soot in the DPF based on fuel consumption and the time since the last regeneration. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 15

Which of the following is a true statement?

A) The rate of a chemical reaction typically increases as the temperature increases.
B) The conversion of HC into heat in the DOC is a chemical reaction.
C) The oxidation of soot in the DPF is a chemical reaction.
D) All of the above are true statements.

Question 16

The most important inputs for an electronic unit injector diesel engine include engine speed, the operators speed or torque request (accelerator), and _____.

A) Common rail pressure
B) IPR
C) Injection pressure
D) Engine crankshaft position

Question 17

Technician A says that a 2010 SCR system that only has one NOx sensor at the SCR catalyst outlet would likely use a virtual sensor for the SCR catalyst inlet NOx determination. Technician B says that a smart sensor and a virtual sensor are really the same thing. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 18

A work order indicates that a truck with a 2007 EPA diesel engine is low on power. Which of these would be the first step of the troubleshooting process?

A) Remove the DPF and determine if the performance is restored.
B) Replace the fuel filters.
C) Replace the air filter.
D) Verify the complaint.

Question 19

A 2010 EPA diesel engine cranks but will not start. Which of the following could be a cause?

A) Faulty proportional solenoid in the port helix pump control
B) Excessive ammonia stored in the SCR catalyst
C) In-range failure of a NOx sensor
D) Empty fuel tank

Question 20

An electronic service tool indicates the following information for a diesel engine in a truck that has been parked inside the garage overnight:
- Engine Coolant Temperature: 23°C (73°F)
- Intake Manifold Air Temperature: 7°C (45°F)
- Inlet Air Temperature (air cleaner): 24°C (75°F)
- DOC Inlet Temperature: 24°C (75°F)
What do these readings indicate?

A) The intake manifold air temperature sensor should be replaced without any additional testing.
B) There is an in-range failure of the intake manifold air temperature measurement system.
C) The low intake manifold air temperature indicates the engine is running and the charge air cooler is working correctly.
D) The intake manifold air temperature circuit is likely shorted to ground.