I have a 95 K1500 with a factory tow package and I am in the process of upgrading from a 4-pin to 7-pin connector. The red 12v ACC wire and blue trailer brake wire were both taped back to the harness at the rear of the frame rail.

My question is, where are the other ends of the wires? I have no power on the red wire, no blown fuses and no empty fuse spots labeled in a way that would make me think they were for the trailer wiring. Is the red wire hooked up to the fuse block from the factory? I would assume the blue wire is somewhere in the dash but I cant find it.

I know this info is probably somewhat dated, but I hope someone has done it before.

 

If the trailer package has never been used, you'll find the forward end of that loom also taped back under the hood at the drivers's side cowl. They left the factory unhooked.

Allan