Late to the party, but my post #7 should help regarding the wiring. But keep in mind, info is for a 3.2 L6 not a v8.

http://www.peachparts.com/shopforum/showthread.php?t=271652

The oil pressure sender is part of this harness. It's inexpensive and easy to R&R if wiring repair doesn't correct pressure indication at gauge.