No trailer lights

[rucummins]

Truck is a 2001 2500hd with a 360. Only had the truck for about a month. This is the first time I tried towing with it, I have trailer brakes but no lights at all. Brake, running, turn signals, nothing. I've checked fuses and trailer relay, all working properly.

This is making me think I have a wiring problem somewhere. Does anyone know what color wires control what going to the 7 pin plug?

 

[Katoom]

There's quite a few internet results out there. Like this one..... http://www.dieselbombers.com/towing-hauling/6815-trailer-wiring-diagram-truck-side.html

 

[jimbo486]

I'd put a test light on the terminals of the 7-way connector on the truck side to first determine if you're getting power to that point. Wire color varies slightly between utility/equipment/cargo trailers, RV/campers and commercial/agriculture trailers but each circuit's terminal within the plugs are in the same position, as you can see below. No idea why there can't be a standard for them use the same color wiring regardless of the trailer's duties.

I wired the plugs on my truck following the utility/equipment/cargo trailer layout. The only difference being that I swapped the black for red as the 12v (+) battery connection since red is standard for 12v (+) in the automotive industry. I also have a relay between the truck harness and 7-way for the running light circuit to protect the headlight switch