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Caterpillar c7 no power no boost

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by BUSbarn, Oct 11, 2017.

  1. Oct 11, 2017 #1
    BUSbarn

    BUSbarn Bobtail Member

    5
    3
    Oct 11, 2017
    Gatesville tx
    0
    We at the bus barn have a 2004 caterpillar c7 that is barely pulling it's self around, very little power and has a few codes such as boost pressure voltage high, oil pressure voltage high, and barometric pressure voltage high. On live mode view from my snap on diagnostic, oil pressure is reading 78.2 psi and will not move no matter if throttled or at idle, boost is at 0.00 and will not move as well. Anyo e ever ran into this issue? Thinking maybe bad sensor or shorted wire but would 1 sensor effect all 3?
     
    BUSbarn, Oct 11, 2017
    BUSbarn, Oct 11, 2017
    #1
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  3. Oct 12, 2017 #2
    ClineER

    ClineER Light Load Member

    229
    139
    Apr 27, 2016
    N.E. Oklahoma
    0
    Check power wires to ecm first. Then cat runs power and grounds for several sensors. With several codes it could just be a broken wire to that sensor group
     
    ClineER, Oct 12, 2017
    ClineER, Oct 12, 2017
    #2
    RET423 and BUSbarn Thank this.
  4. Oct 15, 2017 #3
    carkey351

    carkey351 Bobtail Member

    1
    0
    Oct 9, 2017
    0
    this will sound silly, but have you checked all the the rubber/silicone boots? I know if a boot slips off or is leaking air bad the C7 turns into quite the pooch. Had it happen on an LMTV, (army truck), although it was quite noticeable sound wise that something wasn't right.
     
    carkey351, Oct 15, 2017
    carkey351, Oct 15, 2017
    #3
  5. Oct 15, 2017 #4
    AModelCat

    AModelCat Road Train Member

    29,139
    158,335
    Jul 7, 2015
    Canuckistan
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    I would almost suspect a poor ground on those sensors.
     
    AModelCat, Oct 15, 2017
    AModelCat, Oct 15, 2017
    #4
    BUSbarn Thanks this.
  7. Oct 16, 2017 #5
    BUSbarn

    BUSbarn Bobtail Member

    5
    3
    Oct 11, 2017
    Gatesville tx
    0
    So I'm not sure if I fixed the problem on accident or if what I did put a temporary fix to a bigger issue but I unplugged all three sensors and cleaned the plugs with air, checked with multi meter and plugged them back in and all of a sudden I have boost, I have correct readings on both oil and temp gages and it's got it's power back! I'm still suspecting a wiring issue bad ground or faulty wire but as of now I guess we'll drive it until next time. Thanks for the input guys
     
    BUSbarn, Oct 16, 2017
    BUSbarn, Oct 16, 2017
    #5
  8. Oct 22, 2017 #6
    FoolsErrand

    FoolsErrand Road Train Member

    2,877
    12,169
    Sep 15, 2017
    0
    Ive stripped a few miles of copper wire in my life. Its not uncommon to see salt corrosion or breakdown from age the entire length of a wire. Bad resistance values to the ecm will do all sort of voodoo, wiggling the harness around could have restored continuity. When i worked in avionics we called it gremlins. The ones you cant prove exist
     
    FoolsErrand, Oct 22, 2017
    FoolsErrand, Oct 22, 2017
    #6
  9. Jun 28, 2018 #8
    buster55

    buster55 Bobtail Member

    1
    0
    Jun 28, 2018
    0
    I have a 2002 f750 dump truck with a c7 cat and I’ve noticed the turbo don’t spool like it use to and can’t hear it at all but it still has power but not nearly like it did before. I was wondering if a rubber boot is leaking in front of the turbo or is something wrong with the waste gate not sending boost to the engine?? If anyone knows what it could be that would help out a lot. Thanks
     
    buster55, Jun 28, 2018
    buster55, Jun 28, 2018
    #8
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