Pinpoint Test T: Both Reversing Lamps Are Inoperative
Reversing Lamps
Pinpoint Tests
Pinpoint Test T: Both Reversing Lamps Are Inoperative
Refer to Wiring Diagram Set 93, Reversing Lamps for schematic and connector information. Diagrams By Number
Normal Operation - Manual Transmission
The PCM sends a voltage reference signal to the reversing lamp switch through circuit 1789 (VT/WH). When the transmission is placed in REVERSE (R), the reversing lamp switch closes and routes the signal back to the PCM through circuit 359 (GY/RD). The PCM then sends a message to the Smart Junction Box (SJB), through the Instrument Cluster (IC) gateway function, over the communication network. The SJB then provides voltage to the reversing lamps. The SJB is provided voltage from the Bussed Electrical Center (BEC) through circuit 1679 (WH/YE) to power the reversing lamps.
Automatic Transmission
When the PCM detects the transmission is in REVERSE (R), a message is sent to the SJB, through the IC gateway function, over the communication network. The SJB then provides voltage to the reversing lamps. The SJB is provided voltage from the BEC through circuit 1679 (WH/YE) to power the reversing lamps.
The PCM sets DTCs if any faults with the digital Transmission Range (TR) sensor inputs are detected.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Reversing lamp switch (manual transmission)
- Digital TR sensor input (automatic transmission) concern
- BEC
- SJB
- PCM
PINPOINT TEST T: BOTH REVERSING LAMPS ARE INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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T1 CHECK THE SJB OUTPUT
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Select the SJB reversing lamps (BACKUP_1, BACKUP_2) active command. Command the reversing lamps on.
- Do the reversing lamps illuminate?
Yes
For vehicles with an automatic transmission, REFER to Transmission Control Systems to continue diagnosis of the digital TR sensor. Testing and Inspection
For vehicles with a manual transmission, GO to T2.
No
GO to T4.
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T2 CHECK THE REVERSING LAMP SWITCH
- Ignition OFF.
- Disconnect: Reversing Lamp Switch C169.
- Connect a fused jumper wire between the reversing lamp switch C169-A, circuit 1789 (VT/WH), harness side and the reversing lamp switch C169-B, circuit 359 (GY/RD), harness side.
- Ignition ON.
- Do the reversing lamps illuminate?
Yes
REMOVE the jumper wire. INSTALL a new reversing lamp switch. REFER to Reversing Lamp Switch Service and Repair. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to T3.
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T3 CHECK CIRCUITS 1789 (VT/WH) AND 359 (GY/RD) FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175t.
- Measure the resistance between the reversing lamp switch C169-A, circuit 1789 (VT/WH), harness side and the PCM C175t-21, circuit 1789 (VT/WH), harness side.
- Measure the resistance between the reversing lamp switch C169-B, circuit 359 (GY/RD), harness side and the PCM C175t-41, circuit 359 (GY/RD), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to T7.
No
REPAIR the circuit in question. TEST the system for normal operation.
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T4 CHECK CIRCUIT 1679 (WH/YE) FOR VOLTAGE
- Ignition OFF.
- Disconnect: SJB C2280h.
- Measure the voltage between the SJB C2280h-29, circuit 1679 (WH/YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T6.
No
VERIFY the BEC fuse 62 (20A) is OK. If OK, GO to T5. If not OK, REFER to the Wiring Diagrams to identify the possible cause of the causes of the circuit short.
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T5 CHECK CIRCUIT 1679 (WH/YE) FOR AN OPEN
- Ignition OFF.
- Disconnect: BEC C1035a.
- Measure the resistance between the SJB C2280h-29, circuit 1679 (WH/YE), harness side and the BEC C1035a-D9, circuit 1679 (WH/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new BEC. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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T6 CHECK FOR CORRECT SJB OPERATION
- Ignition OFF.
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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T7 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new PCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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