Trailer Brakes Work but Brake Controller Gives NC Error Message

Question:

I installed this controller unit on my 02 F150 along with the 7 way wiring harness. I checked all the wire connections and correct fuses installed but the controller says n.c. when my trailer is hooked up, But the brakes work fine on the trailer. I just would like the display to work on the trailer so I can see the braking power being used. Any ideas?

asked by: Dan H

Expert Reply:

It may be a dirty trailer connector or a bad ground that is causing some issues on your brake controller. It could also be a malfunctioning display. The first thing I would check is the controller. Sever the blue wire a few inches back from the controller and use a circuit tester like # PTW2993 to test the end that is coming out the controller. Fully apply the manual override level. If it still reads NC check the wiring going to the controller for loose connections or bad wiring, then test again. If it continues to do the same thing it could be a faulty display.

If it checks out fine with this test the issue is most likely a dirty or corroded trailer connector or ground issue. Check the trailer and vehicle side connectors and clean them out. Corrosion can also build up behind the connectors where the wires attach.

Next check the main trailer ground and the grounds for the brake magnets. They should be attached to a clean and corrosion free bare metal surface. Then check the trailer magnet wiring for nicks with exposed wire that may be touching the metal trailer frame.

The next step is to test the magnets themselves. I have included a link to an FAQ article that will help.

expert reply by: Michael H