91 EB Trailing Wiring Issues

[Steelie Trav]

I have a 91 EB that had the wiring harness set-up. I found out today that it doesn't work. So I got underneath to find that the wires between the plug in the middle under the rear bumper to the plug in the left tailight compartment have frayed. So what I tried to do was get the whole plug to plug from my parts truck but dammit if you have to jack the body up to get it out. Anyways what I ended up trying was just to take the plug to trailer plug part that has all four of the gournd tied together and simply plug it into the socket in the left taillight compartment, no go. So now I'm stuck, I tried to hook it all up manually but that didn't work either, the best I could get was the running lights on the trailer, the really funny thing is that when I tested the voltages at the trailer light I was getting a bouncing voltage 12-0V when the turn signal was on and 12V when the brakes where on, they didn't work at the light.

I a state of confusion....need help please!