I believe the sensor is plugged into the dome lamp assembly, which is on the CAN. I'd try finding out if the cars with rainsensor have a different dome lamp assembly, I'd also look into the other thing I mentioned, the Combination Control Module, and the wiper switch itself.
The info I have on 129 and 140 chassis say the windshield sensor reports direstly to the CCM, but I don't think I have info on your car specifically.

Gilly

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