Take out the stock sending unit just above and in front of the oil filter, and check the pressure with a mechanical gauge that is known good.....better if you use one that shops use, or borrow the "tool" from Auto Zone or like that.
Your stock set up is crap. Its just a glorified warning light, and will read "NORMAL" as long as it sees a min. of 6PSI. You can fix that problem by jumping out the resister an the back of the circuit board where the gauge is.....BUT, I highly recommend you buying a decent quality mechanical dash mounted gauge. The parts stores sell them with everything you will need for under $20. I mounted mine just under the ash tray area....wired its light to the ash tray light....so I can even dim it.
BTW: Your oil pressure should be 40-60 PSI @ 2000RPM.