Trailer Brakes Lock Moving Forward But Release Going Backward on 2003 Chevrolet Avalanche

Question:

When I plug the trailer to the Avalanche the brakes are locked on the trailer going forward but not backward. If I plug the trailer to a Yukon, I have no brakes at all on the trailer. What might be wrong with the Avalanche wiring since that is the vehicle I would be using?

asked by: Joe

Expert Reply:

This is a very strange problem. If your 2003 Chevy Avalanche has a 7-Way trailer connector, make sure that it is pinned out correctly like in the picture I have provided by checking the pins with a circuit tester, # PTW2979, if needed. Then make sure that the trailer is wired to match the Avalanche 7-Way. Anything that does not match up could be causing the problem.

If the trailer is using a 6-Way and you have an adpater that could be the problem. There are 2 ways to wire a 6-Way, the center pin will either be brake or 12 volt power. If the adapter is setup the opposite way of what is required by the trailer, that can cause some problems.

Also check for dirty and corroded trailer connectors at the pins and in the backs were the wires attach.

It is also possible that there some issue with the brake magnet wiring on the trailer. I have linked an FAQ article that shows how to test them. I do not think it is a brake controller problem but I have included a link to troubleshooting brake controllers for you as well.

expert reply by: Michael H