No Trailer Brakes With Brake Pedal after Flat Bed Is Installed on 2004 Dodge Ram 3500

Question:

I am trying to get a brake controller to work on a 2004 dodge 3500 truck. The controller will work with the manual switch, but not with the brake pedal. I understand what the four wires on the controller are and where they need to go. I also understand that having a stop light out can cause this problem. I had recently switched the bed to a flatbed with LED lights, and wired the turn and stop lights into the trucks trailer lights. I thought I could just wire resistors into the stop and turn wires, but I found that I have 9 volts to the right turn, left turn, and stop wires ALL THE TIME. I dont understand that.

asked by: Kevin C

Expert Reply:

If you're not getting trailer brakes with the brake pedal, use a circuit tester like # PTW2993 on the red wire exiting the rear of the brake controller. That circuit should go hot with the brake pedal applied. If you're not getting power on that wire, you likely have a blown fuse on the 3rd stop lamp circuit. It's possible when you removed the original bed, something got shorted and blew the fuse.

As far as the vehicle taillights go, they should be wired into the original circuited that the truck bed did, not the trailer connector circuits. For that issue, I'd recommend contacting the manufacturer of the flat bed.

expert reply by: Mike L