Deck 13: Body Control Modules

Question 1

The J1939 data link could be considered as both an input and an output for a body control module.

Answer 1

True

Question 2

A J1939 message transmitted by the engine ECM which is used by a body control module would be considered a hardwired input since the J1939 data link is connected to the body control module with wire.

Answer 2

False

Question 3

Diagnostic trouble codes (DTCs) always indicate the component that must be replaced.

Answer 3

False

Question 4

The cruise control switches on an International truck with a body controller are hardwired to the engine control module.

Question 5

Referring to the figure shown below, with the switch in the P1 position, the resistance between terminals 2 and 9 would be approximately 5.23k ohms.

Question 6

Which of the following best describes virtual fusing?

A) Microprocessor-controlled MOSFET with current feedback
B) Magnetic field measurement of over current
C) SAE type III manual reset circuit breaker
D) PTC circuit protection device

Question 7

Technician A says that a DTC with an FMI indicating an out of range low condition can be caused by an open circuit. Technician B says that a DTC with an FMI indicating out of range high condition can be caused by an open circuit. Who is correct?

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

Question 8

A diagnosable switch would most likely be connected to which type of body control module input?

A) Pulled-down digital input
B) Pulled-up digital input
C) Analog input
D) Switch input

Question 9

Technician A says that a reference ground is really no different than chassis ground. Technician B says that the reference ground for each electronic module on a truck are typically all connected together to reduce electromagnetic interference. 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 switches in the switch packs on an International truck with a body controller directly source current to the device being controlled such as fog lamps. Technician B says that the Smart Switches on a Freightliner M2 directly source current to the device being controlled. Who is correct?

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

Question 11

A technician is testing a clutch pedal switch on a truck with a body control module. With the clutch pedal not depressed, there are 2400 ohms of resistance across the switch terminals. With the clutch pedal depressed there are 1200 ohms of resistance across the switch terminals. What does this indicate?

A) The switch is defective since an open switch should have infinite resistance.
B) The switch is defective since a closed switch should have near 0 ohms of resistance.
C) Both A and B are correct.
D) The switch may be a diagnosable switch and is operating correctly.

Question 12

Referring to the figure shown below, a disconnected wiper switch would cause which of the following?

A) DTC for wiper switch with an FMI indicating out of range high generated by body controller
B) Body controller would detect wiper switch as being in the OFF position.
C) Body controller would detect wiper switch as being in the High position.
D) DTC for wiper switch with an FMI indicating out of range low generated by body controller

Question 13

Referring to the figure shown below, an open circuit between SW 0 and the associated body controller input terminal would result in which of the following with the wiper switch in the Low position?

A) Body controller would detect wiper switch as being in the High position.
B) Body controller would detect wiper switch as being in the Low position.
C) Body controller would detect wiper switch as being in the Int 1 position.
D) None of the above

Question 14

Referring to the figure shown below, technician A says that a short to ground between Sw 2 and the associated body controller input terminal would cause intermittent wiper action with the wiper switch in the Low or High position. Technician B says that a short to ground between Sw 1 and the associated body controller input terminal would cause intermittent wiper action with the wiper switch in the OFF position. Who is correct?

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

Question 15

Referring to the figure shown below, which of the following is a true statement?

A) The resistor shown between terminals 10 and 12 is used to limit current.
B) The resistor shown between terminals 11 and 9 is used to limit current.
C) The resistor shown between terminals 7 and 9 is used to identify the function of the switch.
D) All of the above are true statements.

Question 16

On a Freightliner M2 electrical system, the ____ is the main controller for the body and chassis electrical system.

A) chassis module (CHM)
B) electrical system controller (ESC)
C) bulkhead module (BHM)
D) engine control module (ECM)

Question 17

Technician A says that the best way to prevent ghost voltage is to always obtain open circuit voltage measurements by placing the DMM voltmeter in series with the circuit being tested. Technician B says that it is never necessary to use a DMM when troubleshooting an electrical problem on a truck with a body control module. 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 the headlamps do not work on an International truck with a body controller. Which of these would be the first step of the troubleshooting process?

A) Replace the part indicated by the DTC.
B) Test for ghost voltage
C) Perform a visual inspection of the headlamp ground circuit.
D) Verify the complaint.

Question 19

The air pressure gauges, fuel level gauge, and voltmeter do not operate on an International truck with a body controller. All other gauges such as the tachometer and engine oil pressure gauge are operating correctly. Which of the following is the most likely cause of the inoperative gauges?

A) Short circuit between CAN + and CAN -
B) CAN + is shorted to ground.
C) Missing terminating resistors.
D) An open CAN + or CAN - circuit between the body controller and the electronic gauge cluster.

Question 20

The multifunction switch on a Freightliner M2 is connected to which electronic module?

A) Instrument cluster unit (ICU).
B) Electrical system controller (ECU)
C) Chassis module (CHM)
D) The multifunction switch is connected directly to the J1939 data link.