It is a simple circuit with 12v on the center of the light socket. When you turn the switch to off it removes the ground. If the sw is on, the ground comes from the door switches.
Take a piece of wire and touch from a ground to the outside of the light socket. If the light lights it is either the ground that the sw uses or the sw. Make sure the bulb fits in the socket tight. If not squeeze the socket without the bulb and replace the bulb.
The ground for that circuit and the 12v comes from Junction Box number one.
Good luck
Friday, March 31st, 2006 AT 5:34 PM