Troubleshooting a Brake Controller That Does Not Work with the Brake Pedal on a 2011 GMC Yukon

Question:

I HAVE A 2011 YUKON THAT I INSTALLED A BRAKE CONTROLLER ON AND WHEN I DEPRESS THE BRAKE PEDAL THE INDICATOR LIGHT BARELY COMES ON AND THEN GOES OUT. THE BRAKES DONT COME ON ON THE TRAILOR UNLESS I DEPRESS THE PEDAL AND USE THE MANUAL ACTUATOR LEVER ON THE CONTROLLER. THE YUKON HAD A HARNESS UNDER THE DASH FOR A BRAKE CONTROLLER AND IN THE PAST IVE HAD TO INSTALL A FUSE IN THE FUSE BOX TO POWER TO CONTROLLER BUT THERE WAS A FUSE IN THE TRAILOR BRAKE POSITION ALREADY. CAN YOU TELL ME WHATS GOING ON?

asked by: Billy C

Expert Reply:

Since the trailer brakes work with the manual override, it would seem that the problem is with the stop light switch circuit. This would be the red wire from the brake controller. It should be spliced to either a light blue or orange wire from your Yukon's brake controller harness. I recommend checking that connection to make sure it did not come loose and make sure the wire was not damaged at all.

The brake controller has power, so I do not think the fuse is the problem, but if you have had to replace the fuse once before, there could be a short somewhere. Again, inspect the wiring as much as you can to make sure the wires were not pinched, frayed, cut or damaged in any way.

You can also make sure the brake controller is level and pointed in the direction of travel. Brake controllers will usually have a range of vertical adjustment, but you should make sure it is level horizontally and pointed in the same direction as the vehicle (see photo).

expert reply by: John H