Troubleshooting Trailer Taillight Signals that Stop Working When the Running Lights are On

Question:

My tow vehicle and camper have a 4 flat connector. All is hooked up correctly. the problem is: When the running lights are on, I have no stop or blinkers. when the running lights are off, everything is working normal.

asked by: Jim U

Expert Reply:

This sounds like a ground issue. 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. 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.

I attached an FAQ article on 4-way installs for you to check out as well.

expert reply by: Jameson C