Horse Trailer Brakes Lock Up When Connected to 1999 Ford F-250

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:

It sounds like either the trailer side connector is not pinned to match the vehicle side connector or there is a short circuit (possibly due to corrosion on the pin or inside the trailer connectors) causing the brakes on the trailer to lock up.

The easiest thing to check first is for dirt/corrosion on the pins and inside each of the trailer connectors.

Then you can make sure that the trailer side connector is wired up to work properly with the vehicle side connector. I have included a picture that shows the functions of the pins in the proper orientation. If your trailer is set up differently then that is likely the problem.

expert reply by: Michael H