Trailer Brake Lights Not Working with a 2002 Jeep Liberty

Updated 08/19/2015 | Published 08/18/2015

Question:

I installed the wiring harness as instructed by directions and still cant get the stop light to work on the trailer. The trailer lights and wiring are working because I hooked it up to another vehicle and all functions are normal. Ive tested the ground wire and have a good ground. I exchanged it for a new one and still having this problem. What could be causing this?

asked by: Mark

Expert Reply:

Since the turn signals and brake lights are carried on the same circuits if the turn signals are working the brake lights should too. If they are not then it is likely a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

I have also included a link to a help article on troubleshooting vehicle side wiring.

expert reply by: Michael H