2007 E61 - what MOST module sends light to the M-ASK?

Discussion in '5 Series' started by Oddsocks, Jul 9, 2019.

  1. Oddsocks
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    Oddsocks

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    A week ago my idrive display stopped, the radio doesn't work and the old business SATNAV DVD won't eject. Using my foxwell NT520 diagnostics tool for the CID (central display) it gave code A46D declaring it as 'malfunction due to peripheral' or 'malfunction of CID by reset of MOST ring'.

    Using the foxwell on the CID module and getting live data, voltages and light levels are good, LVDS is OK but 'monitor status to bus = switched off'. Presumably it should state switched on but is dependant on th e M-ASK getting what it needs from the MOST bus???

    The foxwell live data and tests indicate the M-ASK is working ok (my DIS laptop has a flat battery so can't do any moredetailed tests!).

    I've done some googling as it's often the case that the M-ASK unit has failed (this then doesnt initialise the idrive CID). However,after checking glovebox fuse 34 was ok so today I took the M-ASK out (the car is Jan 2007 build so has the M-ASK 2) and can hear the drive spinning up and trying to read the installed DVD.

    When I take the MOST fibre connectors out of the M-ASK, I can see the M-ASK is generating light, but there is no light coming from the disconnected cable - which indicates the ring is broken. My question is - in a basic E61 (just business satnav and no fancy hifi options) - what module sends light to the M-ASK and what module is next to receive light from it (I don't have a CD changer). Googling implies the TCU is in the loop somewhere but I've not found a thread/diagram showing where that is in an E61.

    At some point in my testing i saw live data that implies there are only 2 MOST users - is that expected (and how would it get that info if the ring is broken?

    I have ordered the MOST loopback plugs from Amazon that should arrive tomorrow to help with faultfinding.

    Last question - what do you usethe MOST Diagnostic port for ((or rather how do you use it ) that issituated in the glove box ( I finally found a youtube video showing where it is, but not what to do with it). Is it just a case of checking its correctly looped and has light?

    My dash is in bits at the moment but I don't need the car until Monday so have time to hopefully solve this.

    Thanks

    Dave
     
  2. JasonH
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    JasonH

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    Your TCU is in the boot under the floor, right in the middle behind the back seats. You can access it in seconds, just need to undo two clips holding the boot floor and take our the whole flexible carpeted floor out (the bit that lifts up to access the spare wheel well).

    The TCU will have a green MOST connector - in and out.

    MULF's and TCU's are notoriously prone to failure.

    You need the MOST connection behind the glovebox if you are reflashing the CCC or CID. It's far far to slow to do it via the OBD2 socket.
     
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  3. Oddsocks
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    Oddsocks

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    Thanks Jason - after I posted this last night I changed browser from google to firefox and asked the same question in their search engine and finally found an image from the US that showed the E61 TCU. Amazon have just delivered by MOST connectors so I'll do some more testing tonight.

    Dave
     
  4. Oddsocks
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    Oddsocks

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    Some progress made last night but still not resolved..
    1. With the MOST fibre disconnected at the MASK and TCU, there is no light shining from the cable at either end. Light was shining from the MASK unit but not from the TCU.
    2. Connecting the fibre at the MASK, light was seen at the other end (at the TCU). If I used the loopback connector and removed the input fiber from the MASK I saw light coming back to the MASK, indicating that both fibres were good and that the MASK and TCU are the only modules in the MOST loop.
    3. With the receive fibre still disconnected from the MASK, I reconnected the TCU MOST fibres and as soon as I did, light appeared at the MASK end. I did a bit more experimenting (I have short length of spare fibre) and as soon as the TCU received an input light it generated an output one.....is this just the TCU doing an internal loop? Shouldn't the TCU generate an output light even with no input?
    4. The foxwell analyser shows no stored faults for either MASK or TCU. The CID still give A46D, malfunction due to peripheral. Live CID data still shows monitor status to bus = switched off
    5. Using the foxwell to perform active tests on the MASK buttons, it correctly detects all of them (power, volume, forward/back and eject)....Given that it detects the eject button but does action it it still seems to me that the MOST is fauly - i wouldnt have thought it needed the MOST ring to be up to action the eject? The CD/DVD in the unit is still being spun up.
    6. With the MOST fibre disconnected from the TCU, the car dashboard shows SOS error. With the fibre reconnected this error does not show (which indicates that the TCU is detecting the input fibre
    Questions....
    1. Should the TCU be generating light on the MOST output even with no fibre connected (it isn't)
    2. Should the MASK eject button work even with no MOST ring connected.
    3. With the TCU bypassed by the loopback (so just the MASK is in the loop), should the MASK function correctly (I.e. a MOST loop with one user is acceptable). The Foxwell live data test in this scenario did report 1 MOST user, but then occasionally toggled to 2. With the TCU in the loop it always reports 2 users.
    4. Am I ok to still exclude the CID itself - if that was teh faulty unit I would still be able to get audio?


    Thanks
    Dave
     
    Last edited: Jul 11, 2019
  5. JasonH
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    JasonH

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    A long time ago when I had a faulty MULF and the car was under warranty BMW didn't have a replacement MULF in stock so they fitted a loop connector in place of the MULF. Obviously nothing MULF related was functional but everything else was restored and worked perfectly.

    The MOST is a loop.

    On my MULF there are also a host of electrical connections so I suspect some functionality is wired.
     
  6. Oddsocks
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    Oddsocks

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    Thanks - that supports my theory that the MASK should work on its own with the TCU disconnected - but its not. Time I think to buy a used module.

    I also found this useful youtube thsi morning it implies that the MASK is the only light generator, the other modules need the input light before any light is passed on.
     
  7. slim_boy_fat
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    slim_boy_fat WARLORD Site Supporter

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    If it comes to that, have a word with either Quarry Spares or FABDirect, both specialist BMW breakers. They might be able to find a module with the exact same part number [sometimes parts are superseded by 'updated' ones which might not be exact matches] - this might save you having to code the replacement to the car? :cautious:
     
  8. Oddsocks
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    Oddsocks

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    Thanks for the recommendations -unfortunately I didnt see it after I'd placed an order. I had put my original part number in RealOEM and printed out the list that were 'bilaterally replaceable' and then bought one on ebay that matched (I'd been looking for some days). I had noticed that many sellers on ebay put the wrong part number in the title or in the detail - so i checked each image for the part number and the fact it was M-ASK 2 (and not the earlier ones that mentioned E60 on the label).

    From what I'd read, I assumed that the MASK would power up etc but if the replacement used unit had not previously been coded with modules that existed in the recipient car those would need coding - from my perspective I didn't think that would be a problem as I don't have a CD changer, no HIFI amp, just the basic TCU for bluetooth (and basic bluetooth).
    I'll update when I receive it (expected Wednesday). If it does need coding I have used the tools some years ago to change my battery from 80 to 90 so can probably do it after a bit of googling.

    Thanks for the responses.

    Dave
     
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