Troubleshooting a P3 Brake Controller that Always Sends Current and Brake Lights are On

Question:

After towing yesterday my brake controller was showing that the brakes were on with a force of 3.2 when brake pedal was not depressed. Pulled on brake pedal to make sure it was not stuck.. Also verified that brakes on trailer were actually on, and they were.. Is controller malfunctioning? Brake lights on truck and trailer were lit. Disconnecting plug turned lights off

asked by: Jay B

Helpful Expert Reply:

What I would do is disconnect your brake controller from your truck and see if the brake lights of your truck continue to stay on. If so, then the problem is not the controller and could be that some of the wires of the controller are shorting out to each other. Specifically the black (12 volt power) and the red (stoplight switch.)

If the problem goes away with the controller disconnected then the controller has shorted out and is backfeeding current onto the brake output circuit of your vehicle wiring.

Before replacing the controller you might check the brake controller wiring looking for any obvious signs of a short and fix as necessary.

I also attached an FAQ on troubleshooting brake controller installs plus a video on testing a brake controller for you to check out.

expert reply by: Jameson C