Hi there;
Does anyone know how to test this sensor? I've tested the resistance and that was okay. Whil engine running the voltage dropped according the tables in Chiltons, but what I do not under stand, is how it works.

there is a Red/Gray and a Gray wire.... The gray wire shows the dropping voltage, but I do not measure any voltage at the gray/red one.. Can anyone tell me if this is okay? There are no faultcodes.

best regards Ton van der Sluijs
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Gy/R is a ground (SIG RET). The circuit is a voltage divider; as the sensor resistance drops, so does the voltage dropping across it, so the voltage in the EEC rises, indicating the change.

 

Goodmorning Steve
Thanks a lot for your reaction; It did crossed my mind as well that it was a ground, but I thought that the gry/rd should have the maximum voltage, but it was wrong. The way you explained it made a lot clear to me about the whole sensor system.
The reason for checking the sensor was, that my truck runs at best when the air outside is dry and warm. I did blocked off the EGR, and I because the incoming air doesn't get warmed up by that, the mixture is probably to rich, because of the voltage doesn't drop far enough. I'm thinking about an electrical solution to influence PCM the idea as if the EGR warms up the incoming air. what is your oppinion about that?

best regards Ton