Troubleshooting Tekonsha Prodigy Brake Controller Thats Putting Out Voltage Without Brake Input

Question:

I have a prodigy brake controller that I purchased about 3 years ago from a trailer shop where I live but they are no longer in business and my controller stopped working. it will apply the brakes on my fifth wheel while driving down the road. I noticed that when I turn the key on now it does not show n c then c it just starts to read voltage by its self. touch the brake pedal and voltage goes to 0.0 then starts to climb to 4.0 or so all the time . checked for voltage and ground also signal wire all checks fine per wiring harness.

asked by: Lloyd C

Expert Reply:

As a first step, you'll want to do some troubleshooting to determine if the brake controller is truly faulty. Start by unplugging the wiring harness from the rear of the controller for a minute or two. This will allow the controller to reset.

Then, determine if the controller is still putting out power without input from the brake pedal. Use a circuit tester like part # PTW2993 on the red and the blue wire exiting the rear of the controller. The only time you should see power on that blue wire is when the manual override switch on the bottom of the controller is activated or when the vehicle brakes are stepped on. If you're getting power without the switch or the brakes, then the controller is indeed faulty and should be replaced.

The only time you should see power on the red wire is when the brake pedal is pressed. If you're getting power any other time, your brake stoplight switch is likely faulty and should be replaced.

Also, make sure your trailer connector isn't corroded or damaged. Excessive corrosion could cause power from the 12-volt accessory circuit to feed back into the brake controller output circuit.

I'll link you to our Brake Controller Troubleshooting Article, which you should find helpful.

expert reply by: Mike L