I bought a new Neochanger for my '99 taurus. It came with the RCU hookup cable, but only 2 wires (yellow and black) for power hookup. It says to run black to ground and yellow to 12v source. I noticed another connector that is not being used. It is 3 prong w/ 3 wires (blue, yellow w/ red, and black w/ red). Can I use this for the power? If so, which wire is the hot one? Thanks.