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No start. How does ECM get oil pressure signal?

4226 Views 26 Replies 9 Participants Last post by  bukhntr
I'm working on a no start situation and I believe I may have lost lube oil pressure. Does the ECM require an oil pressure signal to start or will the engine start with no pressure until the HPOP reservoir is empty?

Does anyone know how the ECM gets the oil pressure signal? I know the sending unit on top of the HPOP supplies the dash guage with information but does it also signal the ECM that there is adequate oil pressure to start?

The HPOP is full. Engine has plenty of oil. I have changed the CPS and IPR and have tried disconnecting the ICP, but still no start.

I have checked for codes and have none except for low ICP signal when I disconnected it and a TPS signal which I always have since I spliced the wire for my idle throttle control.

Am I missing something here? /ubbthreads/images/graemlins/shrug.gif /ubbthreads/images/graemlins/confused.gif
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The mechanic is correct in the fact that the engine will not run without oil pressure, but the oil will be depleted from the HPOP reservoir and prevent the injectors from working. If there is oil in the reservoir, then you have oil pressure. The only oil pressure signal that is fed to the PCM is from the ICP and that signal is used to control the IPR.
If you don't have smoke out the exhaust when cranking, then you aren't getting fuel into the cylinders. Use a guage to check your fuel pressure, then use a guage to check your oil pressure from the HPOP. If your pressures are correct, then you may have electrical problems. Have a Buzz test done, then get back to us and let us know what you have found so far.
Do your diagnostic step by step in a logical sequence and it will be a lot easier to locate the problem. Good luck.
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