Troubleshooting Brake Controller Stops Working When Headlights are Turned On for a 2002 Ford F-350

Question:

Wondering why my brake controller would stop working when I turn my lights on any suggestions

asked by: Scott

Expert Reply:

The only thing I can think of that would cause the brake controller to stop working when you turn on the headlights on your 2002 Ford F-350 is that if it was hardwired when installed, the red wire could be connected to the wrong wire on the brake switch above the brake pedal and it is backfeeding into the brake controller.

If it was hardwired when installed, you will need to check the wire that the red wire is connected to using a circuit tester like the Quickee # 3808. The wire should only carry a signal when the brake pedal is pressed. If it carries a signal when the lights are on or when the blinkers are engaged, it is not the correct wire.

If you used the wiring harness, # 3035-P, it could be a similar problem. You will have to probe the pin on the vehicle side and step on the brake. Again, it should only show a signal when the brake pedal is pressed. If it shows a signal at any other time, then the brake controller will not work properly. In this case you will need to remove the red wire just before the connector and splice it into the correct wire on the brake switch located above the brake pedal.

expert reply by: Michael H