Troubleshooting EOH Trailer Brakes on Tandem Gooseneck Trailer

Question:

I have a 20 foot steel deck tandem dual gooseneck with electric over hydraulic brakes when I plug the brakes into my 2006 Ford F-350 with a factory brake control it automatically locks up the brakes and I get a trailer fault I plug the same cord into my 2011 half ton GMC with an aftermarket brake control and it will flash a number and then flashing error code I cannot pull the trailer with properly with brakes on the 2006 because it will not disengage the brakes could it be a dead Breakaway battery causing it to do that thank you so much

asked by: William

Helpful Expert Reply:

Not all trailer brake controllers are compatible with electric-over-hydraulic (EOH) actuators because these present a very different electrical load to the controller than electric drum brakes. Some controllers will have a menu option to let you choose EOH operation but not all have this capability. You will want to make sure both of your vehicle's brake controllers are indeed EOH-compatible; many aftermarket units like the Prodigy P2 # 90885 are.

A dead breakaway battery would not cause the brakes to lock up nor should it cause the error messages. For a new battery use part # HM20008.

If you are using any type of wiring adapter, such as a 7-way to-6-way, that could be the problem. Such adapters can be wired in one of two ways. The linked article on wiring shows the usual function/pin assignments on a 6-way. The center pin can carry either brake power or 12V auxiliary power. If the trailer is set up in a way that does not match the adapter then this would cause the 12V auxiliary power feed to reach the actuator.

expert reply by: Adam R