Troubleshooting Trailer Brake Controller that Only Works Right When Headlights are Off

Question:

My trailer brake controller will only work when lights are off, and if I touch the brakes the light turns off. Without touching the brakes I can adjust the level and apply brakes. What is going on

asked by: Tim

Expert Reply:

Test the wire you used for the stoplight circuit of the brake control install with a circuit tester like part # PTW2993. Make sure it sees voltage only when the brakes are applied with the head lights off and on. It sounds like you may picked the wrong circuit to use for this and that is why your brake controller is behaving strangely.

The other possible scenario is that your vehicle has a weak charging system and can't handle the load of having both your lights and brake controller drawing power at the same time.

expert reply by: Jameson C