Hello,
The only schematic I have in a haynes manual shows a green wire running from pin 2 of the round multi-pin connector at the coolant temp gauge, inside the car at the instrument cluster, all the way to the sender (location not specified). I think the sender is located on top of the thermostat housing, but the wire going to it is black?? I got no continuity from the inside of the car at the instrument panel (green wire at pin 2), to the black wire at this sender unit, so I'm confused. Is this the sender unit for the coolant temp? And, if so, I guess the wire changes from green in the car to black at the engine? And, if so, is there a typical problem with continuity on these cars?
Lastly, I'm measuring an open cct (infinite ohms) between the sender terminal and ground. I would expect the resistance to be something like 850 ohms (like the other one on the side of the engine), with the engine not running (ambient temperature of 75 degrees). So, I'm assuming this sender is bad in addition to a non-continuity problem to the gauge.
Sorry for the long post, but thanks if you can help.

-Jeff
83 300D Turbo Deisel Coupe