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Thread: VCDS Limitations when replacing new moules on a MQB Platform

  1. #21
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by DV52 View Post
    This strongly suggests "unidirectional" - I think (if I understand Uwe's use of the term correctly)
    Yes, that's what I mean.

    But it's nice to have empirical confirmation (thanks kamold) to what is claimed in the documentation.

    -Uwe-
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  2. #22
    FoRT jyoung8607's Avatar
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    Quote Originally Posted by DV52 View Post
    The other question that you haven't asked is: is it possible avoid CP errors when swapping constellation modules? The answer is YES (well....... it's a type of YES in theory). I've not done this, but theoretically, if it's possible to hot-swap any of the constellation modules after a successful CP challenge/response process has been completed (i.e. post ignition switch-on) - it should be possible to avoid CP errors. Of course this would only apply for the current ignition cycle - once the ignition is switched-off and if the replaced module remains installed, a CP error will occur at the next ignition switch-on
    That would be a very interesting experiment. I can tell you the VIN gets announced on the bus continuously, in a multiplex message repeating every 800ms. And for MQB, there's some signature-looking stuff embedded in the message I had previously thought was CP related. PQ has a similar cyclic mux message but with a different ID and there's no signature in it.
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  4. #23
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    An example scenario:
    Turn car to accessories.
    Unplug instrument cluster.
    Plug in foreign instrument cluster (used) and you WON'T get a CP message immediately.
    Newly installed cluster will power up and display as normal.
    However this does NOT have any bearing on immobilizer. So if you try and actually start the car, it will fail as immo adaptation has not been performed.

    If as an alternative the cluster is NEW, it will immediately display CP active on the cluster (as new parts ship with CP already enabled, and no FEC).
    Likewise if ignition is cycled, or the cluster installed whilst the car is off (also this will result in ABS coding being wiped....always take an autoscan and full vehicle admap before starting anything like this!)

    So while the VIN might be being broadcast continuously after initial ignition on, it appears it's not for CP purposes.
    2011 Skoda Octavia vRS TDI DSG wagon|Revo Stage 1|Race Blue|Leather|Dynamic Xenons w 6000K|THA475 Amp+active sub|Whiteline ALK|RVC|Discover Media
    2009 R36 wagon|Biscay Blue|RVC|Tailgate|ECU and DSG tune|LED DRL/Indicators|Full colour MFD|Quad LED tail rings| Climatronics upgrade| Dynaudio retrofit | B7 RLine Flat Steering Wheel|3AA CCM|B7 Adaptive Cruise with Front Assist|TPMS Direct|Discover Media retrofit|PLA 2.0|Lane Assist|BCM Retrofit|HBA/FLA

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  6. #24
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by jyoung8607 View Post
    That would be a very interesting experiment. I can tell you the VIN gets announced on the bus continuously, in a multiplex message repeating every 800ms.
    Do you know which module is sending those messages?

    -Uwe-
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  7. #25
    FoRT jyoung8607's Avatar
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    Quote Originally Posted by Uwe View Post
    Do you know which module is sending those messages?

    -Uwe-
    I'm 99% sure it's the gateway, but I'd have to isolate every bus or test a lone bench gateway to be sure. With my current rig I can only tell you it isn't coming from anything on Extended CAN.

    On MQB, the VIN is muxed in a cyclic message 0x6B4 and it has the funny prefix. On PQ, the VIN is muxed in 0x5D2 the exact same way, but the prefix is all zeros on the only test car I've looked at so far. Unfortunately the test car is, uh, not in factory condition... it's the R36 Passat in kamold's signature. We are working with him to port openpilot to the PQ35/PQ46/NMS family. So I can't say what a factory B6 or B7 Passat would do, or exactly when CP might have been introduced or whether it exists in any form on those vehicles.
    Silence gives consent.

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  9. #26
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    Then the question, what would be the use case of two gateways matched to the same car?

  10. #27
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    My VW Up is sending on 0x5D2 every 200 ms on powertrain.
    It takes 3 messages for complete VIN
    Code:
    199.5  05D2  8  01 5A 5A 5A 41 41 5A 44
    399.6  05D2  8  02 44 30 33 37 35 31 38
    600.0  05D2  8  00 00 00 00 00 57 56 57
    ^ms
    The same for an Audi TT 2007 BUB

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  12. #28
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by downtime View Post
    Then the question, what would be the use case of two gateways matched to the same car?
    I did not have any particular use in mind. It was more an academic question that would confirm whether CP actually works the way it is described, i.e. "unidirectionally".

    -Uwe-
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  14. #29
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    Quote Originally Posted by jyoung8607 View Post
    I'm 99% sure it's the gateway, but I'd have to isolate every bus or test a lone bench gateway to be sure. With my current rig I can only tell you it isn't coming from anything on Extended CAN.

    On MQB, the VIN is muxed in a cyclic message 0x6B4 and it has the funny prefix. On PQ, the VIN is muxed in 0x5D2 the exact same way, but the prefix is all zeros on the only test car I've looked at so far. Unfortunately the test car is, uh, not in factory condition... it's the R36 Passat in kamold's signature. We are working with him to port openpilot to the PQ35/PQ46/NMS family. So I can't say what a factory B6 or B7 Passat would do, or exactly when CP might have been introduced or whether it exists in any form on those vehicles.

    CP exists on PQ for cars such as the 2016 5N Tiguan, 2016 Jetta, T6 Transporter etc that have the Discover Media/Composition Media etc head units. However the CP scheme is simplified, and contains only the instrument cluster as CP master and the 5F infotainment as a module.

    Also, I'm not sure what you are insinuating regarding my vehicle's condition...I bought it like that
    2011 Skoda Octavia vRS TDI DSG wagon|Revo Stage 1|Race Blue|Leather|Dynamic Xenons w 6000K|THA475 Amp+active sub|Whiteline ALK|RVC|Discover Media
    2009 R36 wagon|Biscay Blue|RVC|Tailgate|ECU and DSG tune|LED DRL/Indicators|Full colour MFD|Quad LED tail rings| Climatronics upgrade| Dynaudio retrofit | B7 RLine Flat Steering Wheel|3AA CCM|B7 Adaptive Cruise with Front Assist|TPMS Direct|Discover Media retrofit|PLA 2.0|Lane Assist|BCM Retrofit|HBA/FLA

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  16. #30
    Verified VCDS User DV52's Avatar
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    Quote Originally Posted by kamold View Post
    An example scenario:
    Turn car to accessories.
    Unplug instrument cluster.
    Plug in foreign instrument cluster (used) and you WON'T get a CP message immediately.
    Newly installed cluster will power up and display as normal. ........................
    Kamold:............. except that it appears (I don't know why) that in the case of a used cluster at least, a successful CP interrogation process must have been completed before "hot swapping" the module.

    After reading these posts, I had thought that I had a solution to dealing with CP error on the hex17 module on my MQB test bench: simply energize the cluster module after activating my simulated ignition switch - allowing sufficient time for the CP master to complete its task?

    Alas not successful - same CP error occurs!! Admittedly the test-bench is a very unique set of conditions - but the experiment does add further insight into the mysterious CP process. All I have to do now is understand why - hopefully not as difficult as my current other quest: finding the answer to meaning of life!!

    I suspect that once the CP master records an error on a module - all subsequent attempts to hot-swap further modules are infected with the same complaint (in the newly introduced module). Kind-of similar to jyoung's observations about the transmission of repeated VIN messages on the CAN bus - perhaps?
    Don
    Last edited by DV52; 10-03-2019 at 07:28 PM.
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