Troubleshooting No Trailer Running Lights

Updated 04/27/2015 | Published 04/25/2015

Products Featured in This Question

Optronics Trailer Tail Light - Stop, Turn, Tail - Incandescent - Round - Red Lens

(2630)

$7.10

Hook Probe Circuit Tester

(67)

$13.88

Question:

No running lights on my trailer

asked by: Travi

Expert Reply:

I would begin by testing the trailer connector on the vehicle to rule that out. Turn the headlights on and use a circuit tester like part # PTW2993 to test the socket on the connector fed by the brown wire. If you are not getting a signal on this pin, you might have a blown fuse.

Make sure the ground wire from the connector on the trailer is securely grounded to the trailer frame and that each lamp is grounded to the trailer frame either by an individual ground wire connected to the trailer frame or by its mounting studs being in metal-to-metal contact with the trailer frame. Some trailers use a plastic license plate bracket sandwiched between the driver's side taillight and the trailer frame. The plastic frame can prevent a good ground connection, a ground wire should be ran from the mounting stud to the trailer frame.

Although you have already checked the connections on the running light circuit, they are worth checking again. Make sure you have a continuous circuit from the trailer connector to the lamps, with each wiring connection being secure and protected from the elements.

expert reply by: Jameson C