Short Circuit in Trailer Connector Melted Wiring and Causes Trailer Brakes to Lock Up

Updated 01/20/2016 | Published 01/19/2016

Question:

Can a 12v wire come loose inside, touch a 24v wire and lock the trailer breaks up? When the event occurred, controller reading went up to 8 and the wire was burning about 5 in from connection, if that helps

asked by: Paul

Expert Reply:

On a 7-Way trailer connector there should not be a 24 volt wire. But wires could come loose and make contact with other wires inside the connector and cause a short which is what sounds like happened.

I recommend replacing the trailer side 7-Way with # H20043 which also has a 4-foot lead of wires in case the problem exists further back in the wiring. On this harness the white wire is ground, red is left turn signal/brake light, brown is right turn/brake light, green is tail lights, blue is output to the trailer brakes, black is 12 volt, and yellow is auxiliary 12 volt or reverse lights.

You can also inspect the brake magnet wiring and the magnets themselves to see if they are working properly. I have included a link to a help article that explains how to test brake magnets. Also, if you can see the copper windings coming through on the magnets they will need to be replaced.

expert reply by: Michael H