I have the zp20 ignition box that came with the ZPengine from Horizon but have no wiring diagram. The ignition box has the metallic plug lead and three other wires coming from it. One wire says for tachometer and I think I know where the other 2 go but I really don't want to fry the unit. This is the unit that can take 4.8 to 7.4 volts. Any help would be appreciated. Bill