1992 Chevy Silverado coursity lights

hi, your talking about the interior lites that come on, when you open the door? How come the fuse circuit has no voltage? As far as the switch, look at the door frame, inside where the hinges are, is there a plunger that goes in and out when you open and close the door, that's it. Your going about that the wrong way, don't get mad, just trying to help. Goodluck