Oil pressure gauge problems

[Hemiterry]

Hey guys ! I’m about to go nuts trying to get an accurate reading on my oil pressure gauge on my 2006 International 5600i with a CM870 ISX. First of all I have a mechanical oil pressure gauge verifying that I have 20psi at idle and 40psi driving. I have replaced the sending unit, electrical connector, and the gauge on the dash. This was all done on a fresh oil change and oil filter. At morning startup the gauge reads 60psi and as the oil warms up it drops down to 10 to 20 when cruising and changes readings erratically when hard on the throttle. The big problem is it sits at about 5 psi at idle when hot which sets off the stop engine and engine warning lights. Once again, my mechanical gauge reads perfect pressure at idle to hard loads. Any help would be greatly appreciated.
Thanks, Terry

[Bengy88]

What does insite say the oil pressure is? Always compare the readings in insite to the readings the truck is giving. If insite is reading low oil pressure I would pull a schematic for your engine and load test the wires to the sensor, you can do this by unhooking both sides of the circuit and wire a headlight to run off of the circuit, you want to make sure it is burning good and bright.

[Rawze]

(08-23-2022 )Hemiterry Wrote:  ... The big problem is it sits at about 5 psi at idle when hot which sets off the stop engine and engine warning lights.
...

is this on the mechanical gauge and the sensor reading?.. or just the sensor, but not the mechanical gauge?.

Also, maybe check the +5 volt supply line to the oil pressure sensor. That supply voltage is connected to more than one sensor. Looking up the ECM wiring diagram on Quickserv.com is the place to see what all it connects to.

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If the pressure is actually falling off too much, change the oil filter and see if the pressure comes back up to normal levels for a while again. If it does, then you have an excess soot-packing issue that is getting into the oil and clogging up the filter. That would be very bad.

[Hemiterry]

The mechanical gauge is reading properly and within oil pressure specifications, I just can’t get the electronic gauge to match the mechanical gauge. I’m confident I have proper
Oil pressure. I’ll check the reading on Insite. Thanks

[SemiSweet]

Are you sure the sending unit is a genuine oem Cummins replacement with matching part #? Not an eeBay/Aamazon lookalike? I tried to save some doll hairs once and bought a MAP sensor off eebay and with the key on the damn thing read 4/5 psi manifold pressure lol. Threw that thing right in the garbage.

I’ve seen this with oil/coolant temp sensors as well . They can have different working input/output ranges which don’t correlate with the gauge itself.

I have a little mighty vac hand pump kit which has a bunch of fittings and a mechanical gauge on it. You could use something like this to verify the pressure sending unit.

[Hemiterry]

Yes it’s a genuine Cummins sending unit but now that you mention it the electrical connector was not. I just ordered a new sending unit and connector, both genuine Cummins and I’m gonna start over. A few guys have said they’ve had sending units that were bad right out of the box. Thanks, Terry

[marek4792]

Since you're talking connectors and sensors, make sure you didn't get the set for exhaust or intake air pressures for older engines. I know their pins are different for each purpose, I would rule that out too..

[Hemiterry]

(08-24-2022 )marek4792 Wrote:  Since you're talking connectors and sensors, make sure you didn't get the set for exhaust or intake air pressures for older engines. I know their pins are different for each purpose, I would rule that out too..

Thank you I’ll definitely check that out.

[Rocky]

I have a question and a thought. I've had the exact same issue. My question is; what ended up being the correct part number for the sensor you needed?

My thought was that we both replaced the pigtail connector for the sensor. I don't know about you but every time I make an electrical connection, I use the solder connection with heat shrink. How convenient is it that a majority of soldering metals melting points are just above 200f? Coincidence?