OT- GM "dual connector" ignition coil. 4 wires Jan 24, 2008Got a GM coil (2003 Vortec 6 cylinder engine) that is getting 12 volts as measured at 2 of the 4 wires, but wondering what the other 2 wires are all about ? Getting only a couple of volts output at the coil to distributor wire, so coil seems to be defective but just need to make sure there isn't GM 4-Pin HEI Electronic Ignition Control Module Wiring GM 4-Pin HEI Electronic Ignition Control Module Wiring Connections/Diagram with a Magnetic Pickup Coil. This electronic ignition system operates with full 12 volts. It is recommended only for ordinary lawn & garden equipment.