06 w900 speedometer jumping all over

Discussion in 'Kenworth Forum' started by abtrucker, Feb 11, 2014.

  1. abtrucker

    abtrucker Light Load Member

    131
    30
    Oct 23, 2011
    Alberta
    0
    My speedometer will be working fine, then randomly just jumps up or down. It will even happen when the truck is idling. It will kick the cruise off when it happens, and when it happens under load I can feel the motor kind of lug. I have replaced the speedo sensor with no luck. Truck is 06 w900 with a CAT engine and 18 speed eaton trans. Any ideas??
     
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  3. jameslawton

    jameslawton Light Load Member

    257
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    May 1, 2013
    Tulsa OK
    0
    Check for loose yoke nut on tranny and also where Speedo wires go from ecm to tranny they rub there
     
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  4. Jabber1990

    Jabber1990 Road Train Member

    1,174
    278
    Jan 10, 2013
    Jackson, MO
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    "do you know how fast you were going?"
    "no officer I honestly don't"
     
  5. Whitey14243

    Whitey14243 Medium Load Member

    359
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    Aug 12, 2010
    Moreland, GA
    0
    I'm experiencing same thing on my 2000 W900L with 7CZ CAT with 18 speed Eaton Fuller. Noticed one day when exiting the highway and came to a stop and went to change my Qualcomm over to off-duty it still had blue screen as if I were still driving and that's when I noticed speedometer was bouncing and tacking out. Then it would go to 0 and stay. I recently changed speed sensor and left back out and it now only does this when I come to a stop and I flip the gray button to the low side of the gear.... Any ideas on what's causing this??? Thanks
     
  6. jameslawton

    jameslawton Light Load Member

    257
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    May 1, 2013
    Tulsa OK
    0
    Same thing yoke nut loose can cause Speedo to move why stopped and it might be worth it to get wires from speed sensor to ecm changed if they get worn or untainted they can get interfaces from other wires and make it bounce also if you have a volt meter check you alt and see if you have any ac current off your alt ecm don't like any ac current bad diode in alt can cause it
     
  7. cumminsISB

    cumminsISB Light Load Member

    176
    10
    Feb 5, 2011
    D'Lo, Ms
    0
    Anybody ever find the cause and fix. Mine is doing same thing except with cruise on when the needle drops back.it causes the cruise to catch up. It causes the truck to surge. When cruise is off it's not as bad.
     
  8. jameslawton

    jameslawton Light Load Member

    257
    65
    May 1, 2013
    Tulsa OK
    0
    That is usually caused from loose nut on tranny yoke if its loose replace the nut and strap kit
     
  9. cumminsISB

    cumminsISB Light Load Member

    176
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    Feb 5, 2011
    D'Lo, Ms
    0
    Checked mine a couple weeks ago. Was not loose then but Will check it again.
     
  10. jameslawton

    jameslawton Light Load Member

    257
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    May 1, 2013
    Tulsa OK
    0
    U wont be able to turn it by hand but if u take drive line down and try and tighten even 1/2 -1 turn can make it bounce I tighten them with a 3/4 or 1in impact they should be very tight depending on transmission but between 600 to 900ft lbs
     
    cumminsISB Thanks this.
  11. cumminsISB

    cumminsISB Light Load Member

    176
    10
    Feb 5, 2011
    D'Lo, Ms
    0
    You wouldn't happen to know the part number for the nut and strap kit, would you?
     
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