Interior lights on the blink

[conner@ra.cfm.ohio-state.edu (David Conner)]

Can anyone offer me a clue as to the workings of the interior lights in my
'87 5000S?
They are supposed to come on when the doors are opened and then go out
automatically after a short time or when the engine is started or the doors
are locked.  
Lately they stay on all the time.  ALL interior lights seem to be affected.
Sometimes they will go out after a while...like maybe ten minutes, but more
often they are still on hours later.
For now I've had to remove the bulbs, etc.
Bentley describes relays for front and rear bulb control, which I've
located, but don't know if they have anything to do with the problem.
Any insight into this latest German electrical gremlin would be appreciated.

Dave C.
in Columbus, Ohio
614-292-1619
conner@cfm.ohio-state.edu