It's spliced with a couple of wire nuts just laying in the underbelly behind that frame rail. You can get to them by dropping that section of the underbelly, or if your lucky, like me, only one of the two wires had broken and there was enough slack to just pull the wires out through the frame rail and redo the splice. It gets wet under there and the wires corrode and break. You should repair it with a waterproof splice.