Troubleshooting Brake Controller that Shuts off When Brakes or Manual Override is Applied

Published 05/05/2015

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Question:

second attempt to solve this controller is still flashing .c. even when you disconnect trailer and when you apply brakes manually or by foot controller goes blank when you let off it flashes .c. again. cleaned all contacts checked all wiring found nothing, can this just be a faulty controller or one of the two relays. need to get up and running. have no problem purchasing new controller even though its only 2 years old

asked by: Scott S

Expert Reply:

Sounds like either the breaker/relay is overdrawing when you activate the controller and is causing it to lose power and shut off when activated. It would be a good time to test the controller though to see if the problem is the controller or the wiring.

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