2012 Kenworth ISX Cummins intermittent engine brake

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by FarmTrucking4020, Jan 20, 2022.

  1. FarmTrucking4020

    FarmTrucking4020 Bobtail Member

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    Nov 6, 2018
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    I have a 2012 Kenworth T660 with the ISX Cummins. I am having trouble with the 3 position engine brake not working all the time. This problem has been going on for a while now but it’s really starting to bother me. Most of the time I have to downshift before it will work. Other days, like yesterday, it worked flawlessly. As soon as I took my foot off the throttle it started working. Today, it worked two times at the very start and one time at the very end after I down shifted twice. I notice too, if I switch between the three positions of the brake, it will quit working for an extended period of time. I bet tomorrow when I fire it up, it will work just fine, and then not the next day. Before I take it to the shop and pay $175/hour for them to throw parts at it, is there anything I should look at first? Appreciate any input.
     
    Last edited: Jan 20, 2022
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  3. BoxCarKidd

    BoxCarKidd Road Train Member

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    Start with tapping the clutch pedal when it does not work.
     
  4. AModelCat

    AModelCat Road Train Member

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    Would also check that the throttle pedal is fully releasing. All it takes is for the ECM to see 1% throttle command and you'll have no jakes.
     
    baha Thanks this.
  5. FarmTrucking4020

    FarmTrucking4020 Bobtail Member

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    Nov 6, 2018
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    I think you're spot on but I would like to check it before replacing if possible. Do you know if the throttle pedal measures based off resistance like a fuel gauge? It would be real easy for me to check that with my volt meter
     
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