Troubleshooting Brake Controller that Shows NC and Locks Brakes Up

Updated 09/04/2018 | Published 09/03/2018

Products Featured in This Question

Tekonsha Primus IQ Trailer Brake Controller - Up to 3 Axles - Proportional

(2156)

$90.04

Hook Probe Circuit Tester

(60)

$12.27

Question:

Controller shows n c trailer brakes lock up

asked by: Darrell

Expert Reply:

Best option will be to test the brake controller to determine what is at fault.

Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like part # PTW2993, you should get output to the controller side of the wire you severed. If the manual slide activates the trailer brake output wire properly, try the brake pedal. If the brake pedal activates the brake output properly also then the problem is farther back either in the vehicle wiring or on the trailer.

If either the brake pedal or the manual slide are not functioning properly you will need to test the wires going into the brake controller. Make sure you have power entering the brake controller on the black wire. On the red wire you will only want power when the brake pedal is pressed.

If there is power on the red wire before the brake pedal is pressed you have connected the red wire from the brake controller to the wrong circuit. You would then need to find the brake switch wire that has power ONLY when the brake pedal is activated.

If these connections check out and the brake controller is properly grounded then there is possibly a problem inside the brake controller.

I am including a link to a video that will show you how to test the wiring on a brake controller.

expert reply by: Jameson C