I own a 2008 F450 4x4 dually with less than 2500 miles on it now. Got in the truck yesterday and got the message: Wiring Fault on Trailer. There is no such message in the book I got with the truck. By the way, it's the same owner's manual that came with the '06 I had. They haven't updated it yet. Anyway, no such message and the clincher is......THERE ISN'T A TRAILER HOOKED TO IT RIGHT NOW!!!! Actually, I haven't pulled anything with it at all (yet). I hit the reset button and the message goes away until the next time I start it. Anyone else out there have this same problem?

 

Most of these have been water intrusion into the trailer plug. Check for proper fit of the cover(s), then you can put a little dab of dielectric compound inside, on the terminals. If that doesn't repair it, the trailer controller is a separate module that can be accessed through the aldl under the dash. You'll have to visit your dealer for diagnostics.

 

I had the exact same thing happen. It was really starting to bother me because it beeped this incredibly annoying chirp every time I touched the brakes. I drove down a bumpy dirt road one day and haven't had the problem since. That was over a couple of months ago so hopefully I won't have that problem again. I didn't have a trailer attached either and that's what was really confusing.