Right Turn and Brake Lights Not Working on a Horse Trailer

Question:

Im having a problem with the brake and right turn light on my horse trailer. Both brake lights and all running lights light up when the trailer is connected and I turn on the trucks lights. The left brake light works as does the left signal, but the right side wont indicate braking or a turn signal. Checking some of the other posts it looks like it might be a grounding issue, so Ill try that. But just incase, is there something else I should be checking?

asked by: Mark

Expert Reply:

This is a classic ground problem. When there is more load on a circuit, like when the running lights are on, and you add more load by applying the brakes or a blinking signal, that is when ground problems show up.

The usual suspects for this problem are dirty trailer connectors and corrosion. Start by checking the vehicle and trailer side connectors for dirt/corrosion on the pins and around back were the wires attach.

Make sure that the main trailer connector ground is attached to a clean and corrosion free bare metal surface. Then do the same with the trailer lights. On aluminum frames, tilt trailers, or trailers with folding tongues it is also a good idea to run jumper ground wires from the lights to the main trailer connector ground.

expert reply by: Michael H