Pinpoint Test Y: The Trailer Reversing Lamps Are Inoperative

Trailer Lamps

Pinpoint Tests

Pinpoint Test Y: The Trailer Reversing Lamps Are Inoperative

Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. Diagrams By Number

Normal Operation

Voltage to the trailer tow connector for the trailer reversing lamps is supplied by the Smart Junction Box (SJB) fuse 16 (10A).

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- Trailer tow connector
- Trailer
- SJB



PINPOINT TEST Y: THE TRAILER LAMPS ARE INOPERATIVE - REVERSING LAMPS

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Before beginning diagnostics, visually inspect the trailer tow connector for signs of corrosion or damage. Repair or install a new trailer tow connector as required.

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Y1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR


- Ignition OFF.
- Disconnect the trailer from the vehicle.
- Apply the parking brake.
- Ignition ON.
- Select REVERSE.
- Measure the voltage between the trailer tow connector pin 7, circuit CAT16 (GY/BN), component side and ground.




- Is the voltage greater than 10 volts?

Yes
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.

No
VERIFY the SJB fuse 16 (10A) is OK. If OK, GO to Y2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number

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Y2 CHECK THE TRAILER TOW REVERSING LAMP CIRCUIT FOR VOLTAGE


- Disconnect: Trailer Tow C473.
- Measure the voltage between the trailer tow C473-7, circuit CAT16 (GY/BN), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
INSTALL a new trailer tow connector. TEST the system for normal operation.

No
GO to Y3.

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Y3 CHECK THE TRAILER TOW REVERSING LAMP CIRCUIT FOR AN OPEN


- Select PARK.
- Ignition OFF.
- Disconnect: SJB C2280a.
- Measure the resistance between the SJB C2280a-21, circuit CAT16 (GY/BN), harness side and the trailer tow C473-7, circuit CAT16 (GY/BN), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to Y4.

No
REPAIR circuit CAT16 (GY/BN) for an open. TEST the system for normal operation.

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Y4 CHECK FOR CORRECT SJB OPERATION


- 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. REFER to Body Control Systems. 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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