okay so i plugged up the a/f gauge today... tapped to the pur/wht wire on the drivers side o2 sensor, above the connector, then i grounded and used a pink wire under the steering colum to give it power, i plugged the battery cable back in...no go, nothing.. ground is good i tested it with a current tester, and power is good also.. what could be the problem....

 

well, you test a ground by checking the resistance between that point and a known good ground, with the power de-energized ofcourse.

You really don't want to run the meter off of one of the wires under the dash, you want to use that wire to turn on a relay that is powered from either a fused link to the battery, or to a fused link on the fuse box. Especially if you have multiple meters.

That should get you started with good power to the meter.