Check the rubber switch by the door (A-pillar or column). Remove it and see if the wire is shorted (or spring is broken).
Edit. Note that it could also be the one by the passenger side or the two back seat ones (B-pillar or column between the front and rear doors). The assumption for the driver's side is that it is the one most frequently used and probably broken first.
Last edited by Tony2005; 11/15/05 02:52 AM.