It was the door switch.
The problem does appear to have been the drivers side door switch. I had initially discounted a door switch problem because the seatbelt arm, the one that hands you the belt, functions properly when the door is closed. I guess there are multiple contacts because I moved the switch around a bit and the lamp timer seems to work properly now. I'll have to take it apart and clean/wd40 it...
However, I noticed the rear view mirror could use a little tightening. How is it removed?