Troubleshooting Trailer Brakes that Lock Up When Connected to Trailer Wiring

Updated 12/09/2014 | Published 12/08/2014

Question:

1995 logan coach competitor 2 horse slant horse trailer brakes lock up when plugged up to 1999 f250 super duty lariat. both have 7 point plugs. lights work but brakes lock up. help!

asked by: RH

Expert Reply:

This is a fairly common problem for trailer setups that use 6-way connectors like the # PK11604 that you referenced. The issue is that there is two accepted ways the connector can be wired up. The only difference between the two setup is that the brake output circuit and the 12 volt accessory circuits are swapped.

It sounds like your vehicle is wired one way and the trailer is wired the other way. What you will need to do is swap the two circuits on either the trailer or the truck. It would probably be easier to swap them on the trailer side of the wiring. Check out the diagram I attached to see where the two circuits are.

expert reply by: Jameson C