Trailer Turn Signals and Brake Lights are Dim when Both are On at the Same Time

Question:

I just installed new lights on my boat trailer. Blinkers one at a time are bright but both blinkers and brake light are dim. Had a hard time with the ground but managed to get a screw through the trailer using a connector. I read someowhere else there could be some other ground on the actually light where it bolts to the frame. Could you explain?

asked by: Colby B

Expert Reply:

A trailer light is either going to have a ground wire or it will ground through the mounting hardware but not both. It does sound like a ground problem you are having on your trailer. 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