Jim,
I have 2 sensors, but your system seems to be a little more entailed than mine. I'm sure it should be with the V8. I have an E320-124ch.
My other sens is a single pole to ground unit.
I remember seeing a post a few months ago that listed
a sensor mod. from Benz for a lower cut in with part # and all, but for the life of me, I can't find it via Search. I thought it was buy Benzmac, but not sure.

My fan set up [ stock] runs high speed aux. off eng. temp, but a/c is high pres. only. Of course, high temps results in high pressure, but the trigger is still pres vs. temp.
[ A good freon level indicator with that set-up. No low fan with a/c with high ambiant= possible low freon charge.
Lower than optimium high side.]
So your temp indicator gage runs off the eng. management ecu ??
Arthur