Got a Volvo truck with an N-14 Cummins engine, 400 hp, 94 model, that the oil pressure warning beeper is coming on when at idle.  Looking at the gauge when this happens it is above 30 lbs, doesn't do it all the time.  Last trip to elevator started doing it after running all day, would come on everytime it dropped to idle, didn't seem like the gauge acted right so I shut the truck down, got a cup of coffee, restarted engine and acted ok for the next hour till I was done.

A couple of months ago someone posted with the low oil pressure on the n-14 and one of the replies made reference to a plastic tab that gets broken or something allowing the low pressure, I think.  Anyone know about this?    Where does this engine gets its pressure for the gauge, rear main?

I should also mention that on this truck we had a problem with it shutting off.  It would die going down the road, would only last for 2-3 seconds but then come back on.  Took it to a JD dealer that was suppose to be good with trucks, spent way too much chasing the problem, thought it was fixed and did the same thing on the way home, went straight to a truck shop.  Ended up being a wire shorting out in the ignition harness, they never did tell me where in the harness it was.  Maybe the wire for the oil pressure sending unit is shorted too?

Any ideas?