1994 E320: At the O2 sensor there are 2 white wires, 1 Gray and 1 Black.. Can anyone tell me exactly where each of these wires go and what they are for?

I tested all of them with the key on and I have: + @ one white wire and - @ the other white, but nothing coming from the black and only a very faint ground coming from the gray. Is'nt the gray supposed to be the + wire for the sensor? Which one goes to the ecm?

Anyone familiar with this?

 

black is control whites are heat non polarity dependent.That enough info?

 

Thanks! This is hard to determine without a shcematic.

Thanks again. Russ