Troubleshooting Trailer Wiring Where Lights Turn Off when Headlights Come On

Question:

When utility trailer is hooked up at night all lights works on trailer .but when I turn on headlights. No trailer lights will come on.

asked by: Ronald

Expert Reply:

Try improving the connection of the main ground wire of the trailer wiring harness. Make sure it is attached to a clean metal surface. Or you can run all of the trailer wires back to the main ground. This is actually the ideal solution. But you can also check the current grounds for the lights to make sure they are making a solid connection to a clean metal surface.

What you described is the classic insufficient ground scenario so finding a way to improve the grounds will fix the problem. When your headlights are on there's the most amperage draw on the vehicle which will be when an insufficient ground problem is most likely to show up.

expert reply by: Jameson C