I had a "wiring fault" on my 5er (05 Mobile Suites) according to the truck computer and I've been chasing it for a while. A few days ago I had the breakaway pulled and it got very hot. As of yesterday I had a hard short in the brake system. So a friend (who is smarter than I) and I spent the day chasing the short. So look what we finally found inside the rear trailer axle.

 

Gee - that wire MIGHT have gotten a little warm... LOL Nice find!

 

What was the wire rubbing up against?
How do you think it happen? Something break?

 

That was called "the smoke test"....

Unfortunately this is a pretty common problem. There should be a grommet in the axle tube where the wire passes through. Over time, the grommets fail or were not installed properly to begin with and they start to short. This happened on one of my racecar trailers. They had not put enough cable in the trailer for a strain relief and it looked just like what you have there..

 

I think that guage of wire looks to be a little small too. Explains why the break away went to lunch.

 

Hard to say exactly what happened. There was a little evidence of a short where wire entered the axle but most of the damage was inside the axle. I had looked at the wiring earlier and did not see the damage on the outside. It was small and surrounded by other wires. Going by it's appearance the wire had been shorting for a long time and that is what the truck computer was telling me. I'm guessing the movement of the trailer would move the wire on and off the metal axle which caused the intermittent "WIRING FAULT ON TRAILER" message from the computer. With non-computer equipped trucks I would not have suspected the short until something got smoked. But that is what happened anyway except it happened with the trailer parked and me looking for the "fault" and not on the highway.

 

Good to see you caught before a driving issue.
Good insight for all of us to check regularly.
I changed out my bil's emergency switch after a similar issue back in MN last summer, unfortunately, no vom to check why it fried.
Will follow up with him on this issue.
Thx.