I was just about to post a question re a similar issue with the sunroof on my 1991 500 SE (W126).
My sunroof is malfunctioning - it would open, but will not close when pressing the switch forward. It does however close when I press the switch upward as if to flip open the sunroof (I realise earlier 126's did not have the tilt function). Furthermore once the sunroof fully closes it then tilts/flips open in one motion all together.
Once in the tilt position the switch has no further effect on sunroof operation ie it is stuck open in the tilt position and I have to crank it closed.
Once in the closed position the swicth will allow the same actions as above untill flipped open.
A friend told me that it is the 'comfort relay' or something as such and that I should disconnect the battery and then reconnect in order to get it to reset.
well, no joy with that!
I must add that my sunroof issue started when I had a locksmith remove the ignition tumbler to cut new keys. As soon as they were done with the car the sunroof issue started and strangely, the passenger r/view mirror AND the cruise control is now dead as well. So I don't know what they did or disturbed or didn't reconnect as they should have.
Where is the comfort relay located?

I apologise if I hi-jacked yr thread.

Thanx

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Free State
South Africa