Trailer Lights Go Out When Headlights and Brake Pedal are Applied

Question:

Applied new flat four wire harness and new lights on tralier. All the lights and turn signals work, but when head lights are the vehicle and step on the brake pedal, tail lights on trailer go out completely. Any advise, thanks

asked by: Eddy

Helpful Expert Reply:

The problem you described sounds like a ground issue. What I recommend doing is running the ground wire for each of the trailer lights (assuming they do not all ground through the mounting hardware) up to the ground used for the 4-way trailer connector. I would then reground the bundle of wires for the lights and connector to a new bare metal spot on the trailer frame using both a self tapping screw like part # FA1131822 and ring terminal like part # DW05762-1. If you need additional wire to run the ground from each light to the trailer connector then you can use part # DW07550-1 which is sold by the foot.

Let me know if that fixes your problem and if not I can see about finding additional solutions for you.

expert reply by: Conner L