How to Test Brake Controller to See if it is Shorted Out

Updated 07/17/2018 | Published 07/16/2018

Products Featured in This Question

Draw-Tite Activator IV Trailer Brake Controller - Up to 4 Axles - Time Delayed

(357)

$103.31

Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional

(6643)

$155.79

Hook Probe Circuit Tester

(60)

$12.27

Question:

Sir, Ive read the article from Davids question and my issue is a little different. The red light comes on when the key is on, there is no display for indicating the setting it is blank, there is voltage when depressing the brake and there is always voltage on the trailer wire. And, the brakes do not activate on trailer. Why is there voltage on the blue wire to trailer when not activated? Is the controller bad? Thanks,

asked by: Denny

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 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.

For a brake controller replacement I would recommend the Prodigy P3 Brake Controller part # 90195. This is our best selling brake controller because of how well it works and how easy it is to setup. This is a proportional brake controller that senses the amount of braking the tow vehicle is applying and applies a proportionate amount to the trailer brakes. This will be the last brake controller you buy. It can easily be transferred to future vehicles as well.