Heck, you're in a car. Couldn't you just pull out a tail light bulb or interior light bulb and do it easier and safer? Seems like an answer to a non existant problem.
Exactly. If I'm in a car with a functional battery, a mess of wire and a slew of light bulbs...why am I looking for a pencil?
And not be be completely dense but...assuming the battery works but none of the interior/exterior lights do, how the heck am I gonna see well enought to split my pencil, strip my stereo wire, and hook up my little gizmo?
Guess I'd better take a flashlight.
Frank2135