I have an 2007 F150 without a factory hitch and only a 4 wire flat connector at the rear bumper. I will be adding a hitch, 7 pin connector, and a brake controller. I have found the brake controller factory connector under the dash and it has only four wires going to it. One wire of each of the following colors: red, green, blue and black. Are these the only wires needed for the brake controller? I am looking at the Tekonsha P2 and their adapter appears to use only 4 wires: red, black, blue and white.
I have already read post about getting the required fuses and relays along with the factory 7 and 4 pin harness to replace the existing flat 4 pin only harness, along with the 7 and 4 pin connector.
Is there some way to tell if the other necessary wires, such as the trailer battery charge wire, are at the rear factory connector that the new 7 and 4 pin harness will connect as well as what colors wires they are? If they are not at the rear connector, I will have to run wires for brakes and charging.
I would like to get the necessary parts and do the work myself rather than pay to have someone else install and wire.
Thanks.

 

Sorry, but this should have been in towing forum. Can someone move it there for me? Thanks.