Back door open - No dome light

[bluevolume]

On my 2000 XLS, the overhead light does not come on when I open the rear driver's side door. It comes on with any of the other 3 doors and the rear hatch.

I'm assuming that it is supposed to come on, so how should I troubleshoot this? I don't see a switch on the door jamb on either side, so I don't know where to start.

Thanks,
Blue

 

[MONMIX]

The switch is triggered off the latch on the inside.
I would pop the panel off and start poking around there.