Brandonf150xlt

I have a 2013 F150 that seems to have the standard row package(trailer sway control, hitch receiver, tow/haul option, and 4 pin connector). I am going to be towing a trailer with electric brakes on it in the next month and already know I had to buy a brake controller. So I installed the controller in the cab and hooked it up to the plug under the dash, but when I went to go hook up the 7 pin connection in the rear, I couldn't find the extra cables to power the brakes. Would I need to run extra cables? Or splice into other cables in the engine compartment? And if I do need to run a new cable, where would I connect it to the harness that the controller is connected to?

Any help would be great
Thanks