RustyJC
That is wrong, the pump is supposed to to be wired straight to the 12v from the truck not to the brake away battery although the brake away battery is charged off the same lead from the truck. The wire from pump to the trailer plug should be a 10 or 12 gauge not the 14 or 16 gauge that is usually comes with the brake away battery kit. Do not rely on those generic batteries. I see at least a dozen of those batteries melted down a year with wires melted right off them. Then your brakes are gone. If you have a full size battery like in a RV or trailers with wenches it is ok to go from the truck to the battery then to the pump. With a full size battery there is no need for one of those little generic batteries.