Pinpoint Test AB: The Trailer Reversing Lamps Are Inoperative

Trailer Lamps

Pinpoint Test AB: The Trailer Reversing Lamps Are Inoperative

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

Normal Operation

The Battery Junction Box (BJB) fuse 38 (10A) receives voltage when the vehicle reversing lamps are illuminated. The voltage is then routed to the trailer tow connector.

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- Trailer tow connector

- Trailer

PINPOINT TEST AB : THE TRAILER 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.

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

AB1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR

- Apply the parking brake.

- Ignition ON.

- Select REVERSE.

- Measure the voltage between the trailer tow connector reversing lamp voltage supply pin, circuit CAT03 (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 BJB (Battery Junction Box) fuse 38 (10A) is OK. If OK, GO to AB2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams

AB2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR

- Disconnect: Trailer Tow C4099.

- Apply the parking brake.

- Ignition ON.

- Select REVERSE.

- Measure the voltage between the trailer tow C4099-7, circuit CAT03 (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 AB3.

AB3 CHECK FOR VOLTAGE TO THE BJB (Battery Junction Box) FUSE 38 (10A)

- Measure the voltage between the BJB (Battery Junction Box) fuse 38 (10A), input side, circuit CLS10 (GY/BN) and ground.





Is the voltage greater than 10 volts?

Yes
REPAIR circuit CAT03 (GY/BN) for an open. TEST the system for normal operation.

No
REPAIR circuit CLS10 (GY/BN) for an open. TEST the system for normal operation.