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Thread: Audi a6 c5 -- vcds won't open airbag controller

  1. #1
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    Audi a6 c5 -- vcds won't open airbag controller

    All,

    My 2000 Audi A6 C5 2.7t suddenly has the "Airbag" light staying on in the instrument display of the dash. The Autoscan included below shows that I'm now experiencing the "implausible" "crash signal" fault 17931 from the airbag controller. The car still generally runs fine but I would really like to clear this code (and the dash light) ... but my VCDS will NOT open the airbag controller (controller #15, I believe). I want to clear the fault code and see if it stays cleared and my dash light goes out ... or whether the fault code quickly recurs (maybe indicating I need to replace/repair the airbag controller? -- which would mean taking the center console and dashboard half apart -- yuck -- hoping to avoid this -- and certainly don't wan't to tear into this painful repair unnecessarily).

    Although you can't see it in the scan result below, when I ran this scan, VCDS complained when it got to the point of attempting to open the airbag controller. A pop-up window said (basically) "No response from airbag controller". If I attempted to open just the airbag controller (rather than run a full autoscan) to read stored faults, I got the same "No response from ... controller" message. And, if I attempted this again soon, I was told (basically) to a.) shut off the ignition switch, b.) wait 30 seconds, and finally c.) turn the ignition back on and try again. None of this helped/succeeded. I never managed to successfully communicate with the airbag controller. (Unfortunately, I have no seriously older scans of my A6 in its younger days to see if VCDS could ever communicate with my A6's airbag controller.

    Finally, my bottom line question: Should my VCDS be able to open (and perform VCDS functions on) this A6's airbag controller? If the answer is "Yes," how can I make this possible?

    Best,
    Jim

    ====== Latest Autoscan Follows ======

    Code:
    Friday,22,March,2019,15:57:47:27555
    VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
    VCDS Version: 18.9.1.0 (x64)
    Data version: 20190114 DS296.0
    www.Ross-Tech.com
    
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    
    Chassis Type: 4B - Audi A6/S6/RS6/allroad C5 (1998 > 2005)
    Scan: 01 02 03 06 08 15 16 17 18 22 34 35 36 37 45 55 56 57 65 67
              75 76 77
     
    -------------------------------------------------------------------------------
    Address 01: Engine        Labels: 078-907-551-AZA.lbl
       Part No: 4B0 907 551 K
       Component: 2.7l V6/5VT     G   0003  
       Coding: 06612
       Shop #: WSC 00000  
       VCID: 2C5D3500DC60942A51-5124
    
    1 Fault Found:
    17931 - Crash Signal from Airbag Controller 
                P1523 - 35-00 - Implausible Signal
    Readiness: 0110 0101
    
    -------------------------------------------------------------------------------
    Address 03: ABS Brakes        Labels: 8E0-614-111-EDS.lbl
       Part No: 8E0 614 111 A
       Component: ABS/EDS 5.3 QUATTRO D10  
       Shop #: BB 24334  
       VCID: 1C3DE5C08CC064AA21-5106
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 08: Auto HVAC        Labels: 4B0-820-043-MY1.lbl
       Part No: 4B0 820 043 K
       Component: A6-Klimavollautomat D64  
       Coding: 00160
       Shop #: WSC 02325  
       VCID: 2241DB38AEA4525AEB-257C
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 16: Steering wheel        Labels: 4B0-907-487.lbl
       Part No: 4B0 907 487 
       Component: E Lenkrad Elektronik D03  
       VCID: 69D38C14131241026A-4B36
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 17: Instruments        Labels: 4B0-920-xxx-17.lbl
       Part No: 4B0 920 980 M
       Component: C5-KOMBIINSTR. VDO D09   
       Coding: 02264
       Shop #: WSC 00000  
       VCID: 2F67220CED76EF3274-5140
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 35: Centr. Locks        Labels:. 4B0-962-258.lbl
       Part No: 4B0 962 258 J
       Component: Central Lock/Alarm  D33  
       Coding: 15949
       Shop #: WSC 25066  
       VCID: 30652170F048F0CA6D-4ED0
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 36: Seat Mem. Drvr        Labels: None
       Part No: 4B0 959 760 A
       Component: Sitzmemory          D05  
       VCID: 2B5F361CD96E931258-4AEC
    
    No fault code found.
    
    -------------------------------------------------------------------------------
    Address 45: Inter. Monitor        Labels: 4B0-951-173.lbl
       Part No: 4B0 951 173 
       Component: Innenraumueberw.    D03  
       Coding: 00001
       Shop #: WSC 02325  
       VCID: 60C59130E028004ABD-4B1E
    
    No fault code found.
    Last edited by Uwe; 04-02-2019 at 09:08 AM. Reason: CODE tags

  2. #2
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    Hi,

    I would start with the obvious: connectors, fuses, relays associated to your controller. Did you check all that? Since it's the airbag controller, I would probably diconnect the battery first as a safety measure...

  3. #3
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    Quote Originally Posted by Classik View Post
    ......Since it's the airbag controller, I would probably diconnect the battery first as a safety measure...
    I'd go a step further, since it is an airbag module, I would go out to the erWin website and download their recommended air bag service information such that you are certain not to do something that might set off the airbag. Disconnecting the battery is a great idea but maybe there are further precautions about which you should be aware. You don't want an airbag going off while servicing.

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  5. #4
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by jimbondi View Post
    Finally, my bottom line question: Should my VCDS be able to open (and perform VCDS functions on) this A6's airbag controller? If the answer is "Yes," how can I make this possible?
    Yes, it should. But you have to understand that the airbag warning light is on by default, and a happy airbag module turns it off. Thus, even if you removed the airbag control module from the car, or there was a blown fuse that prevented it from powering up, or that almost two decade old control module had simply died of old age, the airbag light would still be on, and VCDS would not be able to talk to it.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  7. #5
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    Hi Uwe,

    Yes, I understand that the airbag dash light always comes on initially, at every car start up, and then should turn off soon thereafter (after self-test checks of the airbag system have passed). It always did that, until about 2 weeks ago. Any ideas/feedback on what exactly, beside a truly bad airbag controller, could cause the current inability of VCDS to communicate with it?

    1.) I've made a coarse/quick visual check for obviously blown fuses (found none yet) ... but could check more thoroughly.
    2.) Have you seen this issue before on a C5 A6? Or, on other older Audis?
    3.) Any recommendation on things I can try to to get VCDS and my airbag controller communicating? I'm hoping there are other possible explanations, beyond a truly bad airbag controller, that might explain the failure to communicate with VCDS.

    Thank you for any further feedback / suggestions / insight you can offer.


    Autoscan Improvement Suggestion: Why not have VCDS report, in its autoscan output, that it has tried, and failed, to communicate with my airbag controller? My autoscan report file comes out completely void of any indication that VCDS has even attempted interaction with the airbag controller. Were it not for the temporary "pop up window" indicating an attempted but failed communication, one would never know, by looking at the autoscan report, that communication had been attempted.


    Jim

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  9. #6
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    C5 list: 23 modules
    Your C5: 8 working + 1 failed
    === So you would have lot of "failed".

    I could suggest Ross-tech those entries could be added to autoscan logfile only if car entry was chosen from Myautoscan.txt for those pre CAN era cars.

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  11. #7
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by _Val View Post
    C5 list: 23 modules
    Your C5: 8 working + 1 failed
    === So you would have lot of "failed".
    Exactly.

    Quote Originally Posted by _Val View Post
    I could suggest Ross-tech those entries could be added to autoscan logfile only if car entry was chosen from Myautoscan.txt for those pre CAN era cars.
    Based on the scans I see here and in our e-mails, very few people bother with modifying the MyAutoScan.txt file for their specific car(s).

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  12. #8
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    Quote Originally Posted by jimbondi View Post
    Any recommendation on things I can try to to get VCDS and my airbag controller communicating? I'm hoping there are other possible explanations, beyond a truly bad airbag controller, that might explain the failure to communicate with VCDS.
    • A lack of power to the module.
    • The lack of a good ground to the module.
    • A lack of continuity between the K-line pin on the module and pin 7 of the diagnostic socket.


    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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