Trailer Brake Controller Light Stays On

Question:

trailer brake light staying on

asked by: Sam

Expert Reply:

Brake controllers such as the P3 you referenced # 90195 will go into a sleep mode after about 15 minutes of it sensing no movement. If you peek through the window after 15 minutes then it should be in sleep mode. Opening the door or causing movement to the truck could cause it to wake back up.

If it will not go to sleep then make sure the trailer is disconnected. There could be a short that is causing the trailer to draw power which would make the controller think that it needs to be on. Common sources of this include dirt and corrosion inside or outside of the vehicle or trailer side connectors, bad grounds for the magnets, frayed brake magnet power wires, or bad brake magnets.

Make sure the brake magnets are grounded to clean bare metal surfaces near the magnets and fix any possible brakes in the wiring. Inspect the magnets and if you can see the copper windings coming through they will need to be replaced. To further test brake magnets you can follow the how-to article I have linked.

expert reply by: Michael H