Troubleshooting Trailer Brakes that Only Work with Manual Override Lever

Question:

2011 Ford F-350 on factory controller no brakes except manual then just partial brake. Do not have red wire coming out of controller just 4 wires. I’ve checked the ground.

asked by: Rick W

Expert Reply:

Easy fix for this might be just a blown third brake light fuse. A lot of times that is the circuit that activates the brake controller so check to see if the third brake light of your truck comes on when you hit the brakes and if not replace the third brake light fuse. Other than that you can test the wires going into the controller with a circuit tester like part # PTW2993 to see if one of them has voltage only when the brakes are applied. If so then the controller is bad. If not, then the problem is the activation circuit of the controller.

expert reply by: Jameson C