I'm not getting any temp reading in the dash on my 1975 450SL. All other gauges work and all fuses look good. Car starts cold fine, idles down off of cold idle, etc. But no reading on the gauge.

Is there anyway to test the sending unit (rear in right head) w/o blindly changing it?

Any tests I can do @ the back of the gauge to see if something in btw is the cause?

Other suggestions about what might be the cause?

Thanks!!

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress