i just bought a three bank pro extreme charger and i need to connect the purple wire on the charger to a key activated 12 volt source . the tech help man i spoke with at csi said to connect it to the hot wire on the back of the tach but i have several wires going into the back of my tach because of the engine diagnostics . if anyone has wired one of these chargers up what did you connect the purple wire on the charger to. thanks, chuck