It is there, just atttached to another wiring harness and located above it. It took me about two hours on my back to finally discover it. Once there, the harness connected to the electric brake control without any problems.
I've been towing a two-horse trailer (horses included) twice a week for the past month. Great around the farm and two lane destinations at 55 mph, but a bit strained on the interstate at 65-75 mph - a lot of downshifting.
I bought the GX to replace two vehicles - a commuter BMW, and a horse hauler Suburban 454. Time will tell whether I made a good decision.