"Wiring fault on trailer" message - Ford Truck Enthusiasts Jun 17, 2007wiring fault on trailer message comes on with trailer hooked up. But everything works fine. The higher I have the gain turned up the more the message pops up. Then theres other times if I use the trailer brakes alot under heavy load, The trailer brake controller will turn off and will read trailer disconected. Thus no trailer brakes.Wiring fault - Ford Truck Enthusiasts ForumsMar 28, 2015"trailer wiring fault" code on dashAug 11, 2012" Wiring Fault On Trailer " or " Trailer Disconnected " onMar 18, 2011See more results Ford Truck: Wiring Fault message - Heartland Owners Forum Jul 03, 2012The words "wiring fault on trailer" appeared on the information center of my truck while I was traveling in South Dakota yesterday. I have no idea what it meant. I pulled over the first chance I got and checked the brakes and all the lights on the trailer.ything was working. I then unplugged the trailer from the truck and then plugged it back in.