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Troubleshooting Tekonsha Commander XP Brake Controller that is Progressively Working Worse


Hello, I have a Tekonsha Commander XP brake controller on my 2002 F250. It’s been installed for about 14 years. I recently bought a 2020 Grand design trailer. Progressively getting worse on our first 900+ mile trip, I have now lost almost all pressure control from the controller. The trailer brakes are either off or an estimated 80 applied. I don’t know where to even start for trouble shooting, whether the controller, truck harness or new trailer. Being I have roughly 1,200 miles left on this road trip, I would really like to diagnose it properly instead of just throwing parts at it. Thanks in advance!


Helpful Expert Reply:

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 the Tester, 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.

Due to the age of your controller my guess is it's on its way out and will need to be replaced. The iCommand part # 5535 is a really great replacement solution. It's proportional which means it senses how hard you apply the vehicle brakes and applies the trailer brakes in an equal amount and it's priced really well! I attached a review video for more info on this as well.

helpful expert reply by:
Jameson C

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