2005 GMC Sierra, Trailer Brake, OEM Wiring Harness

[jclick]

I've got a 2005 GMC Sierra that I need to install trailer brake control on. I've got the wiring harness that came with the truck. I've plugged it into "electrical center" under the dash, driver's side near the brake pedal. I plugged the 40 amp fuse into the "lug 1" in the fuse box. I still get now voltage out of the wiring. I put my volt meter on red and black and get no voltage. Is there anything that I am missing? Any other fuse or other thing that needs to be done to get the harness to work?



Thanks... Jason