Trailer Brakes Lock Up when Connected to a 1999 Dodge Ram

Question:

My brakes have always worked great with my Toyota Tundra and 1999 dodge dually. I connected my trailer to the dodge today and the brakes will not release until I disconnected the plug. The small trailer battery is dead will the brakes work properly when I install a new battery.

asked by: Jim W

Expert Reply:

The smaller breakaway battery, if it is dead, can affect the brake operation. It may be tripping the breakaway system (if it has one) or there could be a wiring issue such as a short or a ground problem that you will need to look at.

But since this only happens when the trailer is connected to the truck there could be some dirt or corrosion in the trailer connectors that is causing a constant draw and the brakes to lock. Clean out the connectors on both the trailer and vehicle side and check for corrosion at the backs of the connectors where the wires attach.

There may also be an issue with the brake controller. Sever the blue wire from the back of the controller a few inches and test it with a circuit tester like # PTW2979. The blue wire should only show power when you apply the manual override. If it shows power at any other tie then there is a problem inside the controller and it will need to be replaced.

There may also be a problem with the trailer magnets. I have included a link to an FAQ article that explains how to test them. If there is a bare magnet wire that is touching the trailer frame that can cause a short and constant draw.

expert reply by: Michael H