How to measure the voltage on DPFE?

I took apart the connector from the DPFE sensor and saw it, but I had no idea how to measure the voltage on the DPFE sensor without any modification on it. How do you access the electrode? On which point do you contact your probe from the RCL meter?

Year and engine size please.

Here's the link I used to diagnose the bad sensor on my '01.

DPFE Sensor check (http://rockledge.home.comcast.net/RangerPictureGallery/DPFE-Voltage-Test.html)

Year and engine size please.
'01 3.8L. It is enclosed by black plastic. Without cutting the harness, how can I measure the voltage? I cannot access any metal part keeping the circuit connected.

A pin or or a strand of thin bare wire can be pushed in from the back and the voltages taken off there with the circuit operating.

Good link roadrascal. A safety pin is a good tool to insert into the connector to use as a place for the voltmeter to hook to.

I was able to get the faulty DPFE sensor on my '01 Windstar replaced under the emissions warranty. You may want to check with a dealer before paying for a part.