I just bought a 2011 F250 Lariat that has a receiver on the frame, aux trans cooler and factory brake controller but no 4 or 7 pin connector. I searched under that frame rails and around the back of the truck but cannot locate a plug that looks like a trailer wiring harness.
Any ideas?

 

someone hacked it off. Look on the drivers side up where the receiver is bolted to the frame. Mine from the receiver goes up there then along the frame.

 

I finally found it when I was installing a tailgate assist strut. Yeah I know, lol. It was stuffed behind the drivers side taillight
Installed the 7 pin socket and it all works.

Thanks again for the suggestion.

 

great that you found it. Amazing what some people will do.