What weight oil are you using? These can be finicky with anything other than the required oil. I would make sure you eliminate the obvious by making sure you have a good battery charge and connections. Also check the connections to the the sending unit. You can check the pressure with a seperate tester guage if you have one available. You can also test the sending unit. I have not personally seen, but unfortunately have been told, that several of these have had problems with partial blockage of the pickup screen.
I would install a mechanical oil pressure gage to make sure that oil pressure is the problem. If the screen is partially blocked you will see reduced pressure at all RPM's. Could also be a blocked oil filter that the internal bypass has also failed. -- Chuck
The wife called and said the light was on all the this morning. So she called me...I asked if it was making any noise and she said no. So I am thinking and hoping it the pressure switch...gonna change it tonight
I had a 93 F-150, the oil pressure light came on about 1999 or so. Some where around 2008 it went out (guess the bulb burned out) when I scrapped her last year the engine was still running strong. Nothing else on the truck worked but......