Mike,
Welcome to CHR, and as you're finding out we're not so hung up with things being in the right section around here, unlike some "other places", but one thing that riles folks is to have the same thing posted in several places, because they all show up when we hit "Today's Posts". You might want to PM a Moderator, like mrmustang, and ask that the second thread be deleted - just a suggestion.

Like Mike (34_40) said, check your continuity on the white/red wire, either with an ohm meter or using a test light. I suspect that your "idiot light" used the low pressure switch as a path to ground, with power being supplied to the lamp at all times, just waiting for the low pressure to complete that circuit. Your new sensor is a variable resistor which changes with oil pressure. It is grounded at the connection to the block (you cannot use a full coverage of teflon tape or sealer, as it will insulate your connection. A wrap on the bottom couple of threads is OK if you have to have it). As you have done, power to one terminal of the indicator, and the other side hooked to the sender. Are your OPG connections marked?? If not and if you have a good ground at the block you might try reversing your connections at the gauge and see if that might be your problem?