Troubleshooting Brake Controller that Applies Trailer Brakes After Truck Releases Brakes

Question:

I have a 2004 Dodge Ram 3500 with a Prodigy P2 controller. It has worked great for years, but twice recently, it has continued to apply the trailer brakes after I shut the truck off. Last time, I parked the trailer and shut the truck off not sure if I was pressing the brake when I turned it off, got out and was going to unhook the trailer, but heard a high pitched hum from the trailer axles. Sure enough, the controller said 1.4. I unhooked the trailer cable and the brakes stopped, but the controller continued to show 1.4. I started the vehicle and pressed the brake, but it continued until I unplugged the controller from the truck. I know it stays on 15 mins after the truck is off, but not applying the brakes. Has the controller gone bad and I need to replace or am I doing something wrong?

asked by: Shawn T

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 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.

expert reply by: Jameson C