About 2 hours into my current trip I got a "wiring fault on trailer" message in my truck. All the external trailer lights quit working, no 12v systems inside the unit worked, and the fridge monitor was flashing lo dc (I assume low DC). Brakes worked fine. Got back on the road and as I hit bumps, system starts working but goes in and out. Watching the side marker lights, they can be bright, dim, or out. Any thoughts of what the problem is?

Sounds like a loose ground connection . Could be in your truck plug trailer plug or harness or at your batteries in the trailer. Check the battery connections first being you have no 12v inside the trailer

Most obvious is a loose connection. Like Shane, start with the ground. It can also be the plug "wire". I have a similar issue at times. I'm probably going to start with the cable itself since the connections on the truck are fairly new.

Thanks for the suggestions. Problem solved. Found a wire in the junction box for the trailer connector cable that was badly positioned and had become stripped causing an intermittent short. All fixed!

Glad it was that easy

Me too. Big relief.

Great Job! Aren't you glad it wasn't worse? 😉

For sure! Thanks

Start by checking that the plug on the cord from the king pin box is tightly seated and held in place by the cover on the trucks female plug.

If it's not there, look for loose wires inside the box that this cord enters.

Beyond that you're looking for loose wiring at other locations in the RW.

Since the lights come and go it does not seem to be a fuse.

Have you had any water infiltration which could be causing a problem?

The problem was inside the box at the king pin. Got it fixed...no problem!

Glad to hear it is a NON ISSUE now !

Glad to hear you got it fixed. It is always satisfying to take care of these things.