Checking Power to Oxygen Sensors?? How??

I'm trying to wire up a Innovate LC-1 Wideband Oxygen Sensor and from what I gather I can wire it directly into the existing oxygen sensor harness that plugs into the factory narrowband oxygen sensors. It's for my Megasquirt setup.

How can I test the factory oxygen senser harness to decipher which one is giving me +12V, Ground, and Signal wire? There is 1 black wire and 2 white wires. From what I gather, black (signal), white (+12v), and the other white (Ground). Does the body of the oxygen sensor serve as a ground?

I have tried to find which one is power by using a Multimeter, 1 lead on the battery ground and the other probing both of the white wires, key on and engine running, and still have found no voltage.

Is there something I'm missing or is there no +12v being supplied to the oxygen sensors? Do they need to be connected for the +12v to be detected or can I unplug them and probe the connector like I have been doing.

I have been doing this for the past 5 hours and my head is spinning. Any advice will be appreciated!!!
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I would have to look at a wiring diagram at work tomorrow but you should have 12v at one of those wires for your heater circuit. And yes. the O2 gets one of it's grounds through the O2 body.
Yea there should be 12V going to them, I believe it's a red wire because I found it chaffing where it comes out of the rubber grommet in the firewall and I put in a inline fuse since I needed more length cuz I cut out the bad part. With key on it had 12v going through it. Also I think the orange wire that goes to the back of the intake is also an 02 sensor ground but it's been awhile.