Troubleshooting Brake Controller that Sometime Decides to Pulse While Braking


Hello All, I have a Curt Brake Controller - C51110, purchused it from you about 1.5-2yrs ago, has worked great untill our last trip. it started to pulse, during braking it would just start to turn brakes on and off on 2 sec intervals. I would pull over max out all ajustments and hit the brakes then set back to my settings and all is good for couple hours or more. Dosnt seem to happen because of time on the road or being under heavy load for a long time, last week it haappened right out of the driveway. I tested the unit, solid power out of the Black wire, Blue shows increasing resistance and Red with power when under load. No other lights at apparent on the controller. I cleaned all conections on 7 pin. Thanks for all your time and have a great summer


Helpful Expert Reply:

Sounds like the controller has most likely shorted out and is in need of replacing. It sounds like the wiring of the controller is good, but you can still test everything to be certain as I was a little bit confused by the terminology you used.

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.

helpful expert reply by:
Jameson C

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