How to Test a Brake Controller


A couple weeks ago I was towing and I noticed the trailer didnt seem to be responding to me applying the brakes. I tried adjusting the sensitivity, but the brakes were not coming on had a green light the entire time. I towed again this weekend and the green light wasnt on at all, but I still had trailer lights/ power. Is there a test I can run to see if the controller has failed or could it be something else? Thanks


Expert Reply:

Testing the brake controller is fairly easy. Sever the blue brake output wire and then apply the manual slide. Using a circuit tester like part # PTW2993, you should get output to the trailer brakes. 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

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