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Audi B6 1.8T troubles

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  • Audi B6 1.8T troubles

    I am hoping for some help from here; because I much prefer this forum over others.

    My 2004 B6 1.8t would randomly shut off and not restart. After setting for a bit it would restart. It now will only run about 5 minutes and turn itself off. Then after a few minutes it's ready to start again.

    I am unable to connect to the ECU - vagcom says unable to connect to controller.
    I am able to connect to all the other controllers in the car.

    I swapped the cam position sensor just to rule it out - no difference.

    I made a bench harness that I was able to connect the vagcom to the ECU out of the car.

    In the TCU I get fault 18258 - Powertrain Data Bus: missing from ECU
    P1850 - 003 - Mechanical Failure

    I have checked power and grounds to the ECU. I also checked continuity for the k-line from the ECU to the diagnostic plug - that's good
    I have checked the continuity for the Can High and Can Low lines from the ECU to the TCM; and the ECU to the engine harness plug - all good.

    Beside the ECU there is a large 40A fuse that was blown; I replaced that. From the wiring diagram I think that is for the secondary injection pump.

    I have swapped fuel pump relays and inspected every single fuse I could find.

    According to Ross-Tech k-line test the voltage should be below 9V with the ignition turned on. I have 38V. I have tried to unplug all the controllers (ECU, TCU, ABS, Cluster, Airbag, each door module, convenience module, Radio, Climate control, SAIP, HID module) in the car and it made no difference. I get 14v key off and 38v with key on. The factory radio is currently unplugged.

    Should I continue with this k-line ordeal?
    I'm also concerned that the ECU is bad, is there a better way to test it?

    Any input is greatly appreciated.

    //-\\ ((_)) //)) //

  • #2
    Could you run the car with the data Comms lines cut to the engine ECU as a test? So you would get lots of errors as the module couldn't communicate but if the car runs it points in the direction of the fault.

    Sent from my Moto G (5) using Tapatalk


    • #3
      I will try that today.
      //-\\ ((_)) //)) //