Troubleshooting Brake Controller that Doesnt Apply Trailer Brakes

Question:

Hi there, I install a brake controller in my 2000 GMC Yukon it worked fine until now. When I apply the brakes the reading showes power 10 or 15 but immediately goes back to 0 There is no sign of trailer is bracking. Thanks.

asked by: Frank T

Expert Reply:

It sounds like there may be a short in the output wire. I recommend using a circuit tester like # PTW2993 to check the function of your brake controller on the blue output wire about 6 inches back from your controller when using the manual override. If this gives you a gradually brighter light as you increase the slider and the reading increases in level without dropping, then you have a short along that brake controller output wire between that point and the trailer. Test this same thing at your trailer connector 5 o'clock pin. If it works there, then the issue is on the trailer and you'll need to check function to each brake assembly. If it does not work at the vehicle trailer connector pin, then you will need to replace the wire between the testing point and the 7-way.

If you have a problem with the brake controller reading dropping when testing it 6 inches back from the unit, then you need to double check the ground on the controller. If that doesn't solve the problem, then you will need to replace the controller. I've attached some articles to assist.

expert reply by: Jason S