DPFE Voltage Testing

[DGreatest]

I've looked all over this place and can't seem to find the answer so hopefully somebody here knows. I am trying to test my DPFE sensor. There are 3 wires going into the sensor. I've found websites that say to test the brown/light green wire for a specific voltage and the brown/white wire for a specific voltage. My question is, am I supposed to touch the middle wire at all during the tests or should I just be grounding the negative tip when testing the wires? Any clarification is appreciated.

 

[DGreatest]

Nevermind. Stupid question. I left the middle wire alone and used the negative battery terminal for ground. Voltage came out correct.

 

[2000StreetRod]

EGR info

The following thread may help: EGR System O&T