Noticed this morning that the car wasn't doing the "crack the windows" thing when I opened the door after driving to work. Then again on the way home, and the interior lights weren't reacting correctly.

After a few minutes of experimenting, it seems like the car doesn't realize the door is opening and shutting.

I am assuming there is a switch somewhere in the door, but I can't find anything obvious after a few minutes of googling, and there's no obvious switch in the door jamb. I'm guessing it's internal, within the door, or the latch mechanism itself?

 

On a gen1 car, aka a r50/52/53, you can re-train or initialize the door dip....for some odd reason, so cars seem to forget....
Just make sure the windows still work and are not frozen...
To retrain it (from memory, you can search, but I think this is how it is done), you hold the up switch in the "up" position for 6-9 seconds with the window already up...(not sure, do try 10)....then let go....power has to be on of course.
Good luck!!

 

I had seen that and tried it with no luck - it doesn't seem like a problem with the window, but with the door sensor itself. The car isn't turning on the interior lights when the door is opened, for example.

Everything else works - the window goes up and down as it should otherwise.

 

You can look at realoem.com and find diagrams/skematics of the systems and part numbers, etc...might give you a clue on where the sensor is.