Background: I pulled the engine from my car for a rebuild prior to installing a turbocharger but didn't notice the wire connecting the oil sending unit and the block....and ripped it out when we dropped the motor. No more connection. (whoops) I never got that repaired when I put the engine in the car. Started car, runs fine, put 600 miles on it so far, no oil light on in dash. Everything was going hunky-dory.
Recently, the oil light began flickering at low RPM, so I checked the oil, it was a little low, I added some oil, it went away.
I started the car the other day to take it for a drive (I only drive it once or twice a week), and the oil light came on in full force, so I immediately took the car home and began looking for problems. I checked inside the valve cover, and there's plenty of oil splashing around at idle, my turbo return line is still leaking, so there's oil going through there. The car still has plenty of oil in it.
The only change I made recently to the motor, was to include an oil line restrictor mounted on the turbo itself where the feed line comes in, and I doubt that's related, if anything, that should've increased pressure.
Question: Is there another sensor besides the sending unit plug that is telling the ECU to trigger the light in the dash? I have to believe there is one, since the light wasn't on before, and now it won't go away. This wouldn't be an issue if I had a oil pressure guage to read the pressure, but I don't have one. The car is not smoking, there was no drop in performance when the dash light started acting up, and there is no general chaos going on under the hood.
There's only the one sender that turns on the dummy light. Your problem could be either a bad sender, or the sender wire is shorted to ground. I'd find out what the problem is before running the engine any more.
So that sensor with the wire ripped out of it is what's causing the light? Odd, it wasn't lighting up before. I think I'm still going to drop the pan and see if the pickup is screwed up/broken off or something before I run it again just in case.