Originally Posted by Troy Sloan:
It's very easy and not uncommon at all for these lights to end up reversed from what you may think they should be. To verify which is which, just turn on your ignition without starting the car so both lights a lit. Then disconnect the small wire from the spade connector on the alternator. The light that goes out is the alternator light and the one that stays lit is the oil pressure. Easy peasy!
Ha, I was going to recommend pulling the wire off the oil pressure sending unit, then going for a short drive.