[1retired06]

If you hooked another truck to the trailer and the trailer brakes worked fine, then that would lead me to believe something could still be wrong with the truck. Use a twelve volt tester and check each line at the truck plug. If current is there, that would lead me to believe a trailer problem. Check the trailer connects for current in similiar fashion. That should guide you to either a truck or trailer problem. I would check the trailer connections, particularly the wiring harness where it connects under the king pin, and the plug itself. Look for corrosion, bent or missing connecting clips in the plug. If you have an inbed connection as well as the stock ford bumper connection, check both. Inspect the plug on the truck in similiar fashion. Is the trailer harness plug mating correctly with the truck plug when you hookup. Check the wiring harness under the rear bumper for any loose connections, frayed wires, or shorts. Are all your lights on the trailer functioning properly. The last two times I got trailer fault messages on my old 2005 F350 they were caused by(1) bad connection where my inbed plug was spliced into the stock harness affecting both plugs on the truck, and (2) plug on the trailer harness was not connecting properly when plugged into the truck and vibration would cause intermittent connection failure. If everything is a go re current connections, I would go back to the Ford dealer and tell him the controller itself is suspect. That the process I would go through, but there is probably a smart electrician on the forum who has a much simpler testing methodology.