The 7 pin??
The 6 pin is usually 1 to blue for the electric brake from a brake controller.
A 12V fused hot to power the trailer or camper (usually black on the equipment end)
A 12V neutral (white on equipment end)
Other 3 or 4 wires are for Rt. turn, Lt. turn, stop light, and a neutral. Usually grn, yellow, brown etc etc.
Lots of times the center pin is not connected. I recently learned this, I had expected it to be neutral or positive fused. You could use that wire and run a fused wire from the battery to that connector.
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country