Trailer Turn Signal and Brake Lights Not Working but Running Lights Do Work

Question:

Imy trailer lights will not blink or show break lights only running lights

asked by: Billy

Expert Reply:

There are some tests you can do to determine where the problem is. I have included a link that explains the testing procedure. You will need a circuit tester such as # PTW2993 to test the wiring.

It could also be 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.

expert reply by: Michael H