Lights on Camper Trailer Go Out When the Brakes on Ford Truck are Applied

Expert Reply:

It sounds like you have a common ground problem. When the brakes are applied and the brake lights are illuminating, the highest amperage draw is placed on the wiring system and if you have a bad or loose ground, you will have problems with lights. You will want to inspect to make sure all the light assemblies have a good clean ground connection to metal that is free of rust and paint.

You will also want to make sure the trailer and vehicle side connector have a good ground connection. Inspect the connectors and make sure no corrosion is present inside the connectors. If corrosion exists, you will want to replace the connectors.

I would recommend unbolting the ground connections, and cleaning up the metal or relocating the ground connections to a clean metal surface. This will ensure that any grounding points are good to go and not bad.

If you are using a plastic license plate holder on the left side tail light, this could also be causing a ground issue and you will want to make sure the mounting bolts are making good contact with the trailer frame.

I have linked an FAQ on wiring which also has information on ground problems.

expert reply by: Reno H