Oil Pressure Gage ok, but warning lamp is on/off

[DBF]

Left home without the FSM (dumb).



200 miles into the trip, the engine temp gage in the dashboard started flipping irregularly between normal (1st mark) and a point 2/3 of the way to the first mark.



Another 100 miles, we stopped and checked into a motel (with internet). After coming out to drive from the entrance to the room, the red lamp in the shape of an old oil lantern with drips started flickering on/off.



Checked oil level, it's in the middle of the safe range. The oil pressure gage right next to the warning lamp is where it usually is, almost to the second mark in range.



The engine is running just fine.



Any ideas as to what the cause of this could be? What turns on that lamp? I thought the oil pressure sensor was in behind the power steering pump - is that correct? Are there two sensors?



All help appreciated.



Regards, DBF

 

[MWehmeyer]

DBF - my 91 FSM shows that the oil pressure sender and oil pressure light are on separate wires (ground is via the sender housing). Those two lines go to a 10 way connector on the back left side of the engine outboard of the fuel filter. The sender is on the left side of the block center. On my rig the oil light line is Grey and the temp sender is violet with a yellow trace.



Check the connector and make sure it's clean.



Hope this helps - Mike

 

[southpaw]

A new sender can be purchased at napa they are cheap the senders take a lot of heat and vibs so they malfunction giving bad readings. If it is the sender it is located behind and below the fuel injection pump into the block. It sets in a webb recess so a special thin wall deep socket is needed to remove and install . I dont remember the size but it maybe a 1 1/8 inch. I would bet this is your problem. happy hunting.

 

[Moab4x4]

My oil light was flickering but my aux mechanical oil guage (plugged into port above oil filter) read everything OK pressure wise. The two wires are indeed for two sensors. One is a linear adjusting resistance for the guage and the other is a switch. My switch was going bad. I bought a replacement at local parts house cheap and one from C for a bit more, but the one from Cummins was beefier. I don't know if it makes a difference reliability wise, but the sensor weighed a little more and castings seemed thicker. I am sure either would have worked fine, but I returned the cheap one.

My standard deep socket fit. I don't remember the size either...