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Discussion Starter · #1 ·
I had the CEL pop on while driving Friday, took it to the shop this morning. Already done and back in my hands. It had one code set for Oil Pressure Switch no signal which had unplugged itself, most likely not completely seated at the factory. And one pending code for EGT Sensor fault. I should add I'm a 21 year employee of the dealership and our diesel techs are chomping at the bit to get there hands on the ED to diagnose and learn, so it got done pretty quickly. The tech ordered an EGT sensor just in case that comes up again later. What's odd is that the gauges never faltered, oil pressure was dead center of the gauge all weekend, my tech did comfirm that the digital readout is bs which had been said here in the forums, and oil temp was also normal. So doesn't look like any issues other than teething pains so far.
 

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What's odd is that the gauges never faltered, oil pressure was dead center of the gauge all weekend, my tech did comfirm that the digital readout is bs which had been said here in the forums, and oil temp was also normal. So doesn't look like any issues other than teething pains so far.
I'm not following...

You said the gauges showed normal.

Your tech says what the gauges say is BS...

Ummm...no offence here, but how is your tech more informed than the design and engineering team that built the truck?

Did you mean the CEL was BS?
 

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Discussion Starter · #3 ·
The truck is equipped with an oil pressure switch, it's either on or off. The CEL simply came on because because it was not receiving a signal from the switch. The digital reading in the EVIC is a computer generated estimate based on rpm. That is what he confirmed. Calling it BS was maybe not the best term I could have chosen but it tells me that that generated value has questionably accuracy.
 

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The truck is equipped with an oil pressure switch, it's either on or off. The CEL simply came on because because it was not receiving a signal from the switch. The digital reading in the EVIC is a computer generated estimate based on rpm. That is what he confirmed. Calling it BS was maybe not the best term I could have chosen but it tells me that that generated value has questionably accuracy.
So the EVIC isn't part of the system, then? I mean, how was the EVIC showing you anything, if the switch triggering the system was not being seen? (Get what you're saying, and have heard this before, but unclear as to how the EVIC is actually getting any data to work from if the switch was seen to be "disconnected".)
 

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Discussion Starter · #5 ·
So the EVIC isn't part of the system, then? I mean, how was the EVIC showing you anything, if the switch triggering the system was not being seen? (Get what you're saying, and have heard this before, but unclear as to how the EVIC is actually getting any data to work from if the switch was seen to be "disconnected".)
That's a good question. Why did the gauge continue to show normal and the digital readings as well if the switch was unplugged? I'll visit with the tech when I get a chance.
 

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Wait a minute here! Did I just read that the digital readouts are fake? Just an estimated value based on other performance data inputs? And this came from a tech? Well I'll be darned! That would take some stupid for RAM to try and pull that one off.
 

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Wait a minute here! Did I just read that the digital readouts are fake? Just an estimated value based on other performance data inputs? And this came from a tech? Well I'll be darned! That would take some stupid for RAM to try and pull that one off.
The oil pressure switch in the ram Cummins has always been a dummy switch. As long as there is more than 6-7psi to trigger the switch it pretty much just changes position just to give owners some piece of mind. I would have thought the ED would have gotten a real gauge though, with all the other gauges and switches and knobs I thought something as important as oil pressure would have made the list.
 

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So the EVIC isn't part of the system, then? I mean, how was the EVIC showing you anything, if the switch triggering the system was not being seen? (Get what you're saying, and have heard this before, but unclear as to how the EVIC is actually getting any data to work from if the switch was seen to be "disconnected".)
Its unrelated to the switch. It guesstimates from rpm only is what I gather
 

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It's correct - the oil pressure sensing is just a switch and the gauge in the cluster is a "dummy".

The oil pressure switch is "open" (i.e. not grounded) when it has sufficient pressure. THis is why your disconnected switch appeared perfectly normal to the ECU and it continued sending the "dummy" values to the cluster.
The fault gets stored in the ECU if the pressure is indicated as normal with the engine off which is clearly not possible.

All's well that ends well.
 
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