I've changed the sensor twice already, and the guage is dead. When I unplug it, it stays dead at zero. I had a mechanic put a mechanical gauge on there and he says there is oil pressure. The engine runs smooth as silk, so I know there is oil pressure. The engine is freshly rebuilt with a new high volume oil pump, and the pickup tube was tack welded, so I know for a fact that there is pressure. What next? What could this be?

 

Either your gauge is broken or the wire lead for the gauge is pinched and grounded. With the connector off the sensor, your gauge should read max pressure with the key ON.

To help you isolate the problem, unplug C220 and turn your key ON (don't start). See what the gauge does. The gauge wire is in cavity "B", tan wire.

 

Thanks shoebox. When we tested the cable, it showed that it was a negative cable. We sent a positive signal through there and the guage shot up. I just plugged it in and it works now, but there is obviously a short somewhere. How can I begin to look for this short?