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Cat 6.6 oil pressure issue.

Discussion in 'Shop Talk' started by partsandservice, Jun 27, 2020.

  1. partsandservice

    partsandservice Senior Member

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    563c wheel buncher JCB00321. Oil pressure reads 34psi continuously, engine running or not. Found engine oil pushing into the plug, so I replaced the pressure sensor which changed nothing. Ohm tested the three wires to ecm plug all checked ok. Three wire sensor. I have 5volts supply voltage . The signal wire has 1.66 volts engine on or off. When I have the oil pressure sensor unplugged. The signal wire reads voltage close KIMG0842.JPG to 12v. Any ideas would be appreciated . KIMG0843.JPG
     
  2. Nige

    Nige Senior Member

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    5v power is stabilized sensor supply voltage from the ECM.
    1.66v ought to be pull-up voltage from the ECM seeing as the EOP sensor is a PWM type.
    Can't explain the 11.11v with the sensor disconnected.
    Do you have a schematic.? I can send you one if you need it.

    I think that looks like an ECM or software issue.
    Try re-flashing the ECM with the latest engine software . If that doesn't fix it then I'm thinking the ECM has a fried board component.
     
  3. JD955SC

    JD955SC Senior Member

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    you could unpin that signal wire from the ECM and sensor and replace it with a temporary jumper wire to see what she reads. I am moving to that as a standard trouble shooting technique because that way it tells you very quickly where the wire(s) in question are good or bad or if it’s the component.
     
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  4. partsandservice

    partsandservice Senior Member

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    Well other than the wire, that flash/ecm replacement takes me out of the picture. Thanks for the offer on the wiring schematic but I already have one.
     
  5. Mark250

    Mark250 Senior Member

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    I agree with that. I am now in the habit of unpinning the wires directly at the ECM connector and hard wiring the sensor just to confirm that the harness is not an issue
     
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  6. partsandservice

    partsandservice Senior Member

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    After paying more attention to the wiring harness, I discovered that pin1 and pin 3 on the sensor plug we're backwards. Pin 1 should be 5v ref and pin 3 should be signal wire . Swaped them and all works good . Thanks.
     
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  7. Nige

    Nige Senior Member

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    I wonder how long it had been like that..?
     
  8. partsandservice

    partsandservice Senior Member

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    Me too . This machine has exhaust issues and is locked out and will only run 30 seconds at a time. While I was determing that there was nothing I could do because factory password are needed . When I was looking at the data I realized that the oil pressure was at 34 with the engine off. Needed to be fixed anyway !
     
    Mike L likes this.