T190 low oil pressure light

[BeaverDamVa]

I have a 2007 T190 4500 hours. Engine oil pressure light keeps coming on 04-09 code. It comes on at about the same point every time, a few minutes after the cooling fan kicks into high and the temp gauge is about 1/3 into the green and only at full throttle.

What I have done. Changed the oil and cut the filter open. Filter was free of metal flakes. Replaced the sending unit. Put mechanical gauge in. Gauge reads 65 at idle cold 76 at full throttle. 42 at idle and 57 at full throttle when the light comes on. I've gone so far as to get the light to come on and swapped in the gauge and had my wife drive up a hill and the oil pressure varied between 54-58 psi. Checked voltage, 8.09 cold and 8.03 at temp that trips light. Looked for rodent damage. I can't find any. Disconnected the battery; + terminal was loose, cleaned terminals and made sure they were tight. Light still came on.

One thing is that it had previously thrown some other codes. First was an RPM sensor fault at start up but it ran fine: doesn't run fine when the sensor is unplugged, and went away? Then a couple times there was a fuel pressure code but checking and cleaning the plug seemed to stop that. I also tried jiggling wires to try to get it to trip no luck. Light comes on immediately when sensor is unplugged and goes off when plugged back in.

 

[Roadworthy]

It sounds more like a computer or electrical problem than an oil pressure problem. You may just have a loose or oxidized connector somewhere in your system. Try checking or reseating connectors.

 

[BeaverDamVa]

I am suspecting the Controller 6688439. Currently unavailable through Bobcat $1054 when available. I would expect a bad connector/wire to be more inconsistent in its presentation. A company refurbishes them for a fee. They want you to go through the wiring and plugs before you reach out to them. I did jiggle the harness from the controller back to the oil pressure sensor as I checked it for rodent damage with no change to the presentation. It is starting to be an older machine and I hate unplugging connectors without a good reason. But I guess I am at that point.

 

[BeaverDamVa]

Well, I let the brain rest overnight and since the controller was only sending one code and voltage was 8v on an 8v system I decided to back probe the oil pressure sensor. This was after confirming with a second dial gauge that the pressure was at 57 pounds when the light triggered. The two gauges were within a couple pounds of each other. From searching the internet light should come on around 27 pounds and 2.35 volts at full throttle. Well it triggered with the sensor reading right around that voltage. I bought a cheap sensor off Amazon. I have an OEM incoming. I don't know what the voltage should be for 57 pounds but obviously it should be higher.

The good thing is I found some things in the electrical system that would have been an issue in the future digging around in the guts of the machine. Lost a bunch of time being cheap though.