Troubleshooting Trailer Brakes That Lock Up In Reverse

Updated 05/01/2021 | Published 04/30/2021

Question:

My brakes lock up in reverse but not forward. The magnet actuator arms are pointing to the front, meaning I have the correct backing plate assemblies on the correct sides. What seems to be the problem?

asked by: Paul

Expert Reply:

That's a pretty strange situation. My first suspect would be a corroded connector on your trailer. It's possible that corrosion has built up on the inside of the trailer connector causing the center pin that gets voltage when the transmission is in reverse to 'bridge' to the brake output circuit causing the brakes to actuate. The fact that you're only having problems with the vehicle in reverse would lend some credence to this theory.

I'd check the center pin on the trailer's 7-way connector. If you see any green or white corrosion on that pin, there's a good chance that the corrosion has migrated into the interior of the connector where the circuits attach to the terminals.

If your 7-way trailer connector on the vehicle was factory installed, I doubt the connector on a newer vehicle could cause the problem.

expert reply by: Mike L