ive done some searching and not been able to find any help on two wires.. i have the flat 4 i bought the flat 4 you 7way w/flat 4 the white wires is the ground then the purple is the back up lights and i assume that goes to the purple wire on the rear wire harness. i know im going to have to run a blue brake controler wire back because the plug by the parking break ends after the cab. but thwt is the hot lead where does it go what does it do?

 

I use the 12V key on to charge my winch battery mounted on the trailer. It is also used to charge batteries if you have a breakaway electric brake set-up to if the trailer gets loose from the truck, it automatically locks the brakes.

 

IDK about the wiring as I dont have my AllData in front of me right now but your signature looks very familiar.