It's a simple and cheep fix, the plug in you have has a red wire and a white wire , the red wire is the voltage since wire , hooked to the battery or on gm cars to the headlight switch, when you turn on the headlights its sees a voltage drop and bumps ups the voltage a tad, the white wire starts the alternator , it goes to a light , bulb number 194 , and then to the ign switch, when you turn on the switch it sends 12 volts to the bulb , and since the alternator is not running it loads the white wire to almost a ground , light comes on , when you start the engine the alternator is actived and sends 12 back to the bulb , now sense you have voltage on each side of the bulb , it goes out , and when you turn off the engine the bulb can not supply enough to amps to run the ign system , bulb lights up and engine dies and light goes off untel next time , this is as simple as I can make it , hope it helps or I can draw up a wiring diagram, later Blaine