The W126 ETM says pin 1 is for the gauge and pin 2 is for the glow relay. Reference this picture (look familiar?) -
Pin 1 is on the right, pin 2 is on the left, the plastic connector indexing pin is below. Let us know how that works.
This might be the last time I can help anyone this way until I twist my own arm and get reading glasses. I'm still crosseyed from looking so closely at the sender to see the pin numbers.
Sixto
87 300D