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Cat 2WS codes 26, and 34 where are these sensors?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Big Josh, May 14, 2012.

  1. May 14, 2012 #1
    Big Josh

    Big Josh Bobtail Member

    12
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    Jan 30, 2011
    Oklahoma
    0
    I got a check engine light today, so I flashed the codes and got 26 (barometric pressure voltage high) and a 34 (secondary engine speed loss of signal). Does anyone know where these sensors on the engine? Anyone have specs on these sensors what they should read (volts or ohms)? My truck is a 1995 Kenworth W900. Thanks
     
    Big Josh, May 14, 2012
    Big Josh, May 14, 2012
    #1
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  3. May 15, 2012 #2
    Mr. Haney

    Mr. Haney Road Train Member

    2,693
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    Dec 17, 2008
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    The Atmospheric Pressure sensor mounts to a plate on the left hand side of the engine block. A code 26 doesn't mean that you have a high voltage fault.........it means somehing is wrong with this sensor or wiring harness to the sensor

    Code 34 isn't the secondary engine speed sensor.........it's the only engine speed sensor on this engine and is located in the side of the front structure cover, close to the air compressor. If this sensor fails the engine will stop running. You need to get it checked out quickly, before it leaves you stranded.

    You need to have some plug up a laptop with CAT ET to see if both the codes acurred at the same time. You maybe having a wiring harness issue, instead of a sensor issue.
     
    Mr. Haney, May 15, 2012
    Mr. Haney, May 15, 2012
    #2
    Big Josh Thanks this.
  4. May 15, 2012 #3
    Big Josh

    Big Josh Bobtail Member

    12
    0
    Jan 30, 2011
    Oklahoma
    0
    Well I don't know of any local shops that have Cat ET. I would either have to go to Oklahoma City to Cat or KW, or to Cat in Witchita Falls. I called the Cat service dept. and of course they said bring it in. He said there are 2 engine speed sensors on that motor. I found the sensor next to the crankcase vent hose (blow by hose) by the fuel filter was broken. I was told that was the atmospheric sensor. This truck originally had a 435 5EK in it but it broke the crank at 1.6 million. So this engine is a little new to me as far as sensor placement. When I bought the engine used and got a new 40 pin to 70 pin connector from Cat these have been my only problems.
     
    Big Josh, May 15, 2012
    Big Josh, May 15, 2012
    #3
  5. May 15, 2012 #4
    Big Josh

    Big Josh Bobtail Member

    12
    0
    Jan 30, 2011
    Oklahoma
    0
    Mr. Haney could you PM me. I cannot send you one yet I dont have enough posts. I wanted to ask you some questions not related to this thanks.
     
    Big Josh, May 15, 2012
    Big Josh, May 15, 2012
    #4
  7. May 16, 2012 #5
    Big Josh

    Big Josh Bobtail Member

    12
    0
    Jan 30, 2011
    Oklahoma
    0
    Well get the ole girl fixed up. It was the sensor located next to the blow by hose was darn near broke in half. Maybe some careless filter changing from the boys at the SpeedCo?? Not sure just seemed odd it would break like that. The other problem was the sensor that reads the cranks signal. Both were pretty spendy. 188.00 for the atmospheric sensor and 140.00 for the other one.
     
    Big Josh, May 16, 2012
    Big Josh, May 16, 2012
    #5
  8. Apr 11, 2013 #6
    Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    Hesperia, Ca.
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    Whats the purpose for the atmospheric sensor and if its not working (fault code 26) would it effect the engines performance it what way ? I posted this same question on on the cat codes thread. I didn't want to start a new thread, I figure I would revive the older ones.
     
    Diesel Dave, Apr 11, 2013
    Diesel Dave, Apr 11, 2013
    #6
  9. Apr 11, 2013 #7
    morehp

    morehp Medium Load Member

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    Jun 18, 2012
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    The ECM uses signal from the boost sensor and atmospheric sensor to determine the fuel that will be delivered , the ECM also calibrates its other pressure sensors from that sensor, if there is a high voltage fault or open circuit to that sensor the ECM sets a default of 100kpa
     
    morehp, Apr 11, 2013
    morehp, Apr 11, 2013
    #7
    Diesel Dave Thanks this.
  10. Apr 12, 2013 #8
    Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    Should the sensor be replaced or should I have it checked before ? And what do you mean by default of 100kpa ? The truck still runs ok but feels a little rough.
     
    Diesel Dave, Apr 12, 2013
    Diesel Dave, Apr 12, 2013
    #8
  11. Apr 12, 2013 #9
    morehp

    morehp Medium Load Member

    699
    206
    Jun 18, 2012
    0
    Troubleshoot the code , replace the sensor or wiring that is causing the active code,
    The default 100kpa~ 15psi setting will allow the engine to run untill problem is fixed,
     
    morehp, Apr 12, 2013
    morehp, Apr 12, 2013
    #9
  12. Apr 12, 2013 #10
    CatPowerC15

    CatPowerC15 Medium Load Member

    347
    90
    Feb 18, 2010
    Siler City, NC
    0
    2WS has 2 speed sensors, cam and crank.
     
    CatPowerC15, Apr 12, 2013
    CatPowerC15, Apr 12, 2013
    #10
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