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  • Airbag ECU

    I have the airbag light on, so I bought a reset tool but that failed to recognise the system, so when the MOT was due I took it to my dealership who failed to diagnose the problem (and the MOT), so they took it to their local expert who also failed.
    When the airbag light came on the headlamps dimmed momentarily, my thoughts are to replace the airbag ECU, bought on one ebay, but where is it located on the car?
    Any other views much appreciated.

  • #2
    Have you been moving the seats back and forward?

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    • #3
      Airbag ECU

      Kwoffa,
      I am having issues getting a reply, so if this appears more than once, I apologise.
      Yes, I did move the seats min to max whilst looking for something that may have dropped under, but instead of the light coming on straight away when I parked the car back in the garage it came on the next day 5 miles down the road and the headlamps dimmed just before.
      Plus if it was just a wiring/connector issue BMW would have diagnosed that with an error code?
      I have just found this, so its under the radio:
      http://www.zroadster.net/forum/viewtopic.php?t=26778
      Similar problem if you scroll down far enough, the re-programming is a puzzle, I read that as long as the part number is the same all is OK.
      Thank you.

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      • #4
        So did the dealer just come up with no codes or have no comms with the car at all?

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        • #5
          Airbag ECU

          CW,

          Dealership (and their sub contractor expert) said no comms at all, same as the tool I bought, it did not "log on". I went through all the tips that came with the instructions, sequence of connection/disconnect battery etc but the readout number was from memory, meant no connection.
          Dealership said it could be a wiring problem, but I thought I might start with the ECU as ebay items are cheap enough?

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          • #6
            Bricks...
            The airbag light on after moving seats is a common issue.BMW do an extended harness..which solves the issue you will need one for each seat...i am sorry i cant help with obd port,

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            • #7
              Airbag sensor/ecu is sat on the transmission tunnel below radio and I think you may need to remove console to get to it.

              picture on this thread,

              http://www.z3mcoupe.com/forum/showthread.php?t=16212

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              • #8
                Airbag ECU

                Update, I now have a MOT.

                Could not remove the centre console completely (gearstick/heater controls) but had enough room working through the radio aperture and under the side covers to replace the ECU with an ebay item (£18) same part number 8 374 799.
                Switched on and had the same "no comms" as before from my B800 reset tool, so must be the wiring?
                The 15 amp supply fuse had blown (well spotted Dealership & Local Expert). Replaced fuse and communications with B800 commenced. I got 2 error codes, "supply voltage" (that would be the lack of a fuse?) and "firing circuit, side airbag, front right side". So I'm guessing the error codes are not stored in the airbag ECU as this had been replaced with my ebay item and was sold as "checked and in working condition".
                I reset the light on the assumption the ECU had gone south, hence the MOT.
                The questions I have are:-
                was there a melt down in my front side airbag circuit that caused the blown fuse, i.e. will that airbag deploy when I want it, new ECU appears happy?
                or was there a melt down in the ECU itself?
                and as per some google write ups do I need to get this replacement ECU mapped to suit the cars VIN number?
                But in my case no error codes connected with the moving seat syndrome!

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                • #9
                  Which fuse had blown?

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