Tow 3500hd

[dss56]

This might be kinda tough but here goes!!

A friend of mine has a 3500HD wrecker tow truck. The rear light just stopped working. No brake lights, blinkers or running lights. The front will work Blinkers ,Flashers and running lights. Also he lost his big emergency strob light on top. The truck was rewired for all the LED flasher/strob lights. I have never seen a vehicle with so many cut wires. I guess they are from the factory wiring. I did get the rear blinkers running lights to work but still no brake lights. What I had to do to get this to work was add a ground wire at the back of the truck to one of the white wires on the rear lights. Still no brake lights. Is there some info somebody could supply maybe the wiring for the factory lights. I did check every fuse and relay in the truck I think on the side of the dash, under the dash and under the hood. Also checked the voltage on one side of the fuse blocks to make sure all was getting voltage. Gotta be a bad wire going back to the truck but need the wiring schematic.

 

thanks this is my first post here.