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A weird new one: SPN 1231 FMI 9

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by PermanentTourist, Apr 4, 2023.

  1. Apr 4, 2023 #1
    PermanentTourist

    PermanentTourist Heavy Load Member

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    It says "Emission System No Comms Detected. 25% derate"

    And the truck goes into auto shutdown.

    It's been sitting for a couple of days and got jumpstarted and then this began.

    Is it a loose wire or perhaps a blown fuse somewhere or something?
     
    PermanentTourist, Apr 4, 2023
    PermanentTourist, Apr 4, 2023
    #1
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  3. Apr 4, 2023 #2
    PermanentTourist

    PermanentTourist Heavy Load Member

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    I checked the fuse in the power distribution box, I unplugged and replugged the ACM... now on my way to Walmart in an Uber so I can buy a proper voltage tester (it's 10pm here and it's the only thing that's open)
     
    PermanentTourist, Apr 4, 2023
    PermanentTourist, Apr 4, 2023
    #2
  4. Apr 4, 2023 #3
    JB7

    JB7 Heavy Load Member

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    Possible causes: • Over/under voltage supply to the ACM module • Fault set during a reprogram event • Loss of power to the ACM • Loss of ground to the ACM • Loss of ignition switch power to the ACM • Open in the CAN-H/Can-L communication circuit to the ACM
     
    JB7, Apr 4, 2023
    JB7, Apr 4, 2023
    #3
    PermanentTourist Thanks this.
  5. Apr 4, 2023 #4
    PermanentTourist

    PermanentTourist Heavy Load Member

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    Yes, I have that PDF too lol
     
    PermanentTourist, Apr 4, 2023
    PermanentTourist, Apr 4, 2023
    #4
  7. Apr 5, 2023 #5
    Hammer166

    Hammer166 Crusty Information Officer

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    ~8600+' and loving it!
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    Had something very similar in a DD13. Shortly after delivery this truck dropped the driveline because the front u-joint wasn't tightened up. It did a good job of wrapping and pulling some of the wire harness. 2 years later the communication line to the ACM finally grounded out where it had been pulled tight against the OneBox. IIRC, he was in the shop for a week before they finally found it after running out of parts to throw at it.
     
    Hammer166, Apr 5, 2023
    Hammer166, Apr 5, 2023
    #5
    Oxbow and PermanentTourist Thank this.
  8. Apr 5, 2023 #6
    PermanentTourist

    PermanentTourist Heavy Load Member

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    That's exactly why i'm going under there with the multimeter. It is ~probably~ the harness and a grounded wire, but I want to be sure. Even if I don't end up changing the harness myself, I don't want them throwing a new ACM at me for no reason.
     
    PermanentTourist, Apr 5, 2023
    PermanentTourist, Apr 5, 2023
    #6
    JoeyJunk and Hammer166 Thank this.
  9. Apr 5, 2023 #7
    PermanentTourist

    PermanentTourist Heavy Load Member

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    48 states + Canada
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    Update: I found the bad wire!

    Spliced it with some random wire i scavenged from a 12v charger, and i'm good to go. Saved myself at least a couple grand and a two day delay...
     
    PermanentTourist, Apr 5, 2023
    PermanentTourist, Apr 5, 2023
    #7
    Oxbow, Magoo1968, IH9300SBA and 2 others Thank this.
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