Trailer Brakes Suddenly Activated Themselves without Applying the Vehicle Brakes, 2002 Dodge Ram

Updated 10/04/2011 | Published 10/03/2011

Question:

Yesterday, we trailered a horse about 12 miles using a 2002 dodge 3500 and pulling a 22foot gooseneck trailer. On the way to the event, no problems. On the return, shourtly after we made a left turn, we experienced the trailer brakes locking up without applying the truck brakes. It didnt matter how slow we went, they still locked up immediately. We disconnected the trailer brake plug in the bed of the truck,and made it home However, that means no brake lights, etc. Any thoughts?

asked by: Harlan K

Expert Reply:

That is an interesting problem. I do not think making the left turn caused the issue but it is possible that there is a short circuit in the trailer connectors that caused the 12 volt power circuit to jump to the brake circuit, activating the brakes.

This can happen if the trailer connectors on the vehicle and/or trailer side are dirty or have corrosion build up. Dirt and corrosion can also build up in the backs of the connectors where the wires attach. You will need to clean out any dirt or corrosion you find.

To determine if the brake controller was at fault, you can disconnect it from the truck and see if the brakes release. If they do, you know the issue is the brake controller and you will need to check the wiring to determine if there is a bad connection somewhere or if the internal circuitry as gone bad.

You can also check to make sure both the vehicle side and trailer wiring is intact with no nicks, cuts, or breaks by visually inspecting the wiring and testing it along the length of each wire, periodically probing the wiring with a circuit tester like # PTW2993.

I do not think it is the brake magnets based on the fact that the brakes activated without touching the pedal, but it may be worth visually inspecting them. If you can see the windings coming through, they will need to be replaced. You can also make sure the brake magnet wiring is intact as you did with the other wiring and that the grounds are attached to clean metal. I have included a link to an FAQ article on further testing of brake magnets.

expert reply by: Michael H