Troubleshooting Brake Controller That Gets Hot and Trailer Brakes that Lock Up

Updated 10/12/2015 | Published 10/10/2015

Products Featured in This Question

Curt TriFlex NEXT Trailer Brake Controller - 1 to 4 Axles - Proportional

(925)

$135.95

Tekonsha Prodigy P2 Trailer Brake Controller - 1 to 4 Axles - Proportional

(2763)

$159.19

Hook Probe Circuit Tester

(60)

$12.27

Question:

it always worked fine then we hooked up the horse trailer i calibrated tried to move lockup wait a second it would release so i felt the unit under the dash was hot so i unhooked undid the big round connector and noticed the white wire come undone im thinking it must of shorted out we had it installed by shop with the box getting like it did to hot to ttouch

asked by: Clyde

Expert Reply:

It does sound like there is a short on your trailer. If the brakes locked up and the brake controller unit got very warm it sounds like there is a short on the trailer's 12V power circuit that is causing the electric brakes to lock up. It is possible for different circuits to become bridged together and your 12V power feed might be getting to the brakes.

First, check the trailer plug inside and out for signs of corrosion. Even slight greenish or whitish discoloration can indicate corrosion. You can try a spray-on contact cleaner like Caig De-Oxit to remove any corrosion on the connector. You can also test the trailer wiring by itself by disconnecting the trailer plug from the truck. Apply 12V power from the truck battery (or from a spare) to each circuit on the trailer, one at a time, to make sure everyone functions. If not, trace the wiring for each circuit and look for cracked or worn insulation, especially around points where the wire has to bend and where it touches the trailer frame.

If the brakes engage and release properly when you apply power in this way, then the issue may be in the controller. You can apply a circuit tester like # PTW2993 to the controller's blue output wire to test its function. Cut the blue wire a few inches from the controller (so you have room to re-connect it) and test the end from the controller while you press the manual override. If you detect a signal, then the controller is okay; if not then it may have been damaged from the short-circuit and needs to be replaced with a unit like the Prodigy P2 # 90885.

expert reply by: Adam R