Trailer Lights Only Work Fine when Tow Vehicle Headlights are Off

Question:

I have a camping trailer light that works fine with headlights turned off. Blinker/stop lights work as intended. As soon as headlights are turned on, no running lights/blinker/or stop light, all other lights work fine.

asked by: Mike

Expert Reply:

This sounds like a ground problem. 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 but can show up any time.

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