Wgregb,
Should I start with a BTDT??
I'm the guy that gets called when nobody else can figure out what to do.
In your case, I would lay chips that the cable has been crushed someplace along its run. Sometimes this is not visible. I have used two different methods to locate the damage.
Method 1 - Buy a wire tacker. A cheap one will work. They put a signal on the line and you can follow it until the signal disappears and then hope that you can actually find the damage.
Method 2 - Get a small compass. Rig a light in series with the circuit. As it is shorted, the light should show. Now take the compass and follow the wire path as much as you can as long as you can and watch for the compass to change its reaction. Now you are near the short.
There is a third way to correct the issue, but it can be costly and time consuming. Rewire that part of the trailer. The marker lights might be a real issue, but most of the rest is sort of under the trailer.
Good Luck guy
Matt
