Thanks for the suggestion. I removed the license plate bracket, and found the sensor. I followed the wire back (without removing it) to the rubber grommet that leads into the glove box. I removed the glove box liner and tried to find where that wire leads, but it was difficult to get to alone, so I decided to wait until my friend can help me. Meanwhile, the cable appeared to be in good condition (where I could see it). Is there an easy way to unplug the sensor somewhere inside the dash where I can access it through the glove box opening, so I can see if this is the culprit? Any other tests I could try?

Thanks

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1980 300SD (daily driver), 1981 300D (Inca Red)