how would i connect something so it would turn off when the car does, such as a volt meter, in otherwords. where is the ignition switch wire so i can tap into it, please answer, thanks.,..gerry

there are a couple places you can tap into.

 

You don't need to tap directly into the ignition key source, just a lead that is switched on/off with the ignition. I can't give you a specific spot. You'll just need to prob around with a test light or multi-meter.

 

Other option is to tie the voltmeter into an accessory on/off lead, such as a lead that the radio connects to.

The cigarette lighter hot wire is probably the easiest to tap.