Trying to find signal wire on O2 Sensor

[bwhite757]

I was given the diagram below from a dealership, however I'm having a hard time time finding the signal wire, the ground is definantly the ground on the diagram, but I'm getting 2.5 volts on pins 3 and 4, however pin 4 does fluctuate a little, pin 3 stays a constant 2.5v. You guys got any ideas??? B/C it's becoming a PITA to fire the truck up, test for voltage, and then wait 30-45 minutes for the pipes to cool down enough for me to hook the volt meter to another wire..

http://bcwhite.net/images/o2sensor.JPG

[Painless]

One thought, and apologies in advance if you've already thought of it:

Are you giving the O2 sensor enough time to warm up and start sending the correct signals before you measure voltage? I would say at least 5-10 mins to be safe (if it's not internally heated).

[Smith03Jetta]

Bosche normally uses a BLACK wire as the signal wire on it's O2 or Lambda Sensors.

[bwhite757]

Actually after some more reading, I've found out that yes, the black (pin 4) wire was my signal wire, and what do you know, my vehicle uses a 5 volt signal.. Ugh, guess my 1 volt EFIE is more or less a paper weight..

[Smith03Jetta]

The EFIEs that I've seen are designed to work with the 1-5 volt sensors. The point of the EFIE is to reduce whatever input voltage by a certain percentage. I've never heard of an EFIE that is designed to work on a 1 volt O2 sensor. I didn't know there was such a thing as a 1 volt O2 Sensor. It may be 1 volt at idle but it will go up higher as you are driving.

[dennyk159]

My understanding is that the EFIE is supposed to add from ~.5 to 1.0 Volt to the O2 sensor signal.
You're trying to make a lean condition appear rich... But I have never used one...