Troubleshooting Brake Controller That Is Putting Out Voltage When At Rest

Updated 09/19/2015 | Published 09/18/2015

Products Featured in This Question

Pollak Replacement 7-Pole, RV-Style Trailer Connector Socket - Vehicle End

(745)

$15.62

Hook Probe Circuit Tester

(66)

$14.40

Question:

Installed a Valley phantom brake controller on a 1990 dodge ram p/up per wiring diagram. My problem is : when the brakes are not even applied I am getting approx. 6 volts at the 7 pin brake terminal. I do not even want to hook up a trailer yet fearing the brakes will be partially engaged. Is there possibally something internally wrong with the controller? Help, thanks

asked by: Ron W

Expert Reply:

There could be in internal short in the brake controller. Use a circuit tester like part # PTW2993 on the blue wire exiting the rear of the controller. There should be no voltage on that wire unless the brake pedal is pressed, or the manual brake switch is engaged. If there is voltage, test the red wire. There shouldn't be any voltage on that wire unless the brake pedal is pressed.

If you find voltage on the blue wire, but not the red, try pulling the manual brake switch several times and letting it snap back into place. Sometimes the contacts for the manual brake switch get dirty and actuating it several times helps to clean them.

If you have voltage on the red wire when the brake isn't being pressed, the stop lamp switch on the truck is faulty, and should be replaced.

If you still have output on the blue wire after checking the things mentioned above, the controller is faulty and should be replaced. I'd recommend going with a proportional controller like the Tekonsha Primus, part # TK90160. A proportional controller features internal sensors that can determine how quickly the vehicle is stopping. It will then send the proper amount of voltage to the trailer brakes, so the tow vehicle and trailer stop at the same rate. This provides safe, predictable braking.

You'll also want to check the 7-way connector on the truck. If it's damaged or corroded, the 12-volt circuit might be bleeding over onto the brake circuit.

I'll also link you to our Brake Controller Troubleshooting FAQ article.

expert reply by: Mike L