Trailer Brake Lights Will Not Work and Blow Vehicle Stop Light Fuse when Trailer Is Connected

Question:

All my lights work fine when the trailer is not hitched to the car. When I hitch the trailer on all works except the brake lights which blow the fuse. Any ideas?

asked by: Chris

Expert Reply:

It sounds like there is a short circuit somewhere that is causing an overload condition which is blowing the fuse and/or not allowing the lights to work properly.

To locate a short on the trailer you will start by making sure the trailer connector is clean and free of corrosion inside and out. Then make sure the main ground wire is attached to a clean and corrosion free bare metal surface. Do the same for each light.

Then you will need to examine the wiring from the connector back to the lights. You will be looking for any breaks in the wiring with exposed copper strands touching the metal trailer frame. Repair as needed.

You will also want to make sure that the trailer connector on the vehicle is clean and free of corrosion like you did with the trailer side connector.

expert reply by: Michael H