If the manufacturer bothered with the 7 pin connector and a trailer hitch, the 4 wires you need will probably be bundled together somewhere.
Like everything else, the bundle will be in the LAST place you look.
TT 2015 19RD "TheJayco"
TV 2003 F-350 "Montblanc" - Housebroken chore truck
Sitting in The Cheap Seats.
And proud of it!