since some might not be quite as familiar with wiring as others, I thinkNotch is saying to use the parking light or dimmer circuit (literally taken, the headlight wire would only provide illumination for the new gauge when the headlights are on. i like to have them light up with the other gauge lighting, which is upon parking light illumination). i am pretty sure that is what he meant, but others might take that literally (and search the headlight wire in schematics).