Troubleshooting Brake Controller that Locks Up Brakes When Connected to Tow Vehicle

Updated 03/10/2016 | Published 03/09/2016

Question:

What would cause the trailer brakes to be locked up when I connect the prodigy 2 to the trailer? I had it working on 2 other Ford chassis motirhomes. Now I have it on a Freightliner chassis. I may have made a mistake on the wiring between controller and chassis trailer brake controller wiring. All lights on trailer are ok. Only way to get brakes to release is remove controller. Readout on controller is nc.

asked by: Walt F

Expert Reply:

Go over how you have the brake controller wired to the vehicle. Somehow 12 volts is getting put on the brake output circuit of the vehicle when the controller is installed. Make sure the white wire is going to ground (sounds like it is), make sure the black wire goes to the 12 volt power source, most likely the problem is on the red wire...make sure it is connected to a circuit that only sees power when the brakes of the vehicle are applied.

The blue wire of the controller should be the one that connects to the 7 way of your vehicle for the brake output circuit. It is possible that you have the 12 volt accessory circuit swapped with the brake output circuit.

expert reply by: Jameson C