CAT ET not communicating in a 04 379

Discussion in 'Peterbilt Forum' started by C15Mike, Apr 29, 2018.

  1. C15Mike

    C15Mike Light Load Member

    54
    27
    Sep 15, 2016
    0
    HI I went to hook up my laptop with cat et to my truck today and its not communicating with the ECM. When I bought the truck last year the dealer had to hotwire the ecm to read it, I figured whatever they did they would of left, But they didn't just my luck. I have a constant 12.8 volts to the "B" wire so its not that wire however I have no idea where the other 3 wires in the connector go. Its a 6 pin J1939 connector and has 4 wires total in it. Its a 04 379 with a MBN C15, does anyone have a wire schematic or know where these wires go to in the ECM? Any help is appreciated. Thanks!
     
    Javi08 Thanks this.
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. pushbroom

    pushbroom Road Train Member

    1,769
    7,205
    Sep 1, 2012
    0
    An 04 should be J1708 which is 6 pin vs J1939 which is nine pin.
    Between pin c and e should be 12v.
    A and B should have continuity to the pins on the ECM.
    Post the last six of the S/n for the Pete digrams
     

    Attached Files:

  4. C15Mike

    C15Mike Light Load Member

    54
    27
    Sep 15, 2016
    0
    last six are 813048 Thanks
     
  5. pushbroom

    pushbroom Road Train Member

    1,769
    7,205
    Sep 1, 2012
    0
    Cat and Pete diagrams attached. Check for power and ground first. If you have good power and ground but cannot hookup you have a datalink issue Let me know if you need help deciphering the diagrams or tracking down a circuit.
     

    Attached Files:

    spsauerland, Oxbow and Muddydog79 Thank this.
  6. C15Mike

    C15Mike Light Load Member

    54
    27
    Sep 15, 2016
    0
    Awesome thanks pushbroom!!
     
  7. Muddydog79

    Muddydog79 Heavy Load Member

    820
    2,147
    Apr 14, 2016
    0
    Same engine, same problem here. Thanks for the info fellas.
     
  8. DblElowboy

    DblElowboy Bobtail Member

    16
    4
    Aug 4, 2019
    Atlanta
    0
    we have a 16 glider with a MXS Acert that was unable to connect as well. It reported 1939 data link problem or something can’t remember the exact wording. If it throws codes it does not show a check engine light on the dash either. You can also not check the codes by the cruise control/set method. How do you further diagnose a data link issue? Thanks
     
  9. pushbroom

    pushbroom Road Train Member

    1,769
    7,205
    Sep 1, 2012
    0
    Have you ever been able to hook up to the truck? Gliders kinda suck for diagrams because no idea whose engine harness is on it and if they added the extra datalink in the cab or not.
     
    Goodysnap and spsauerland Thank this.
  10. DblElowboy

    DblElowboy Bobtail Member

    16
    4
    Aug 4, 2019
    Atlanta
    0
    Yes it used to connect without issue. Also check engine light would come on when codes were thrown. Now it doesn’t . Can unplug sensors and drive with no CEL. Low coolant sensor is only one that will show on dash.
    Where and exactly what is the data link?
    It’s a Pete 389 model forgot to add that earlier
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.