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S3 Seats in A3 - Airbag Light - Solved at last

Discussion in 'A3/S3 Forum (8L Chassis)' started by FactionOne, Feb 15, 2008.

  1. FactionOne

    FactionOne Administrator
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    Right folks,

    OK, So in most (if not all) cases when you install S3 seats in an A3, you can't simply plug the airbags on the seats into the wiring on the car.

    Often the car has a three-wire firing mechanism and the airbags on the S3 seats are two wire. From what I can work out looking at the wiring diagrams there is perhaps a fundamental difference in the way the bags are fired - so if you choose to attempt to modifiy either end of the loom and connect the seats that's up to you. If both the bags in the seats fire and you're left covered in expensive leather/alcantara and foam, don't say I didn't warn you!

    So, without the airbags connected, the A3 will throw a fault code and the light on the dash is illuminated. This causes two things; firstly, it's damn annoying. Secondly, and perhaps more importantly, from what I can work out it means that the airbag controller won't even attempt to fire any of the other airbags in the car.

    This means that in an ideal world it would be possible to somehow 'confuse' the car into thinking that the seat airbags are connected, clear the fault code, and everything should be hunky-dory. No warning light and working dashboard airbags.

    OK, so ste_1210 got in touch with me as I'd done some investigating into this issue a while ago; and the other night we were chatting away with him in front of his car and me in front of a pile of wiring diagrams for the A3 and S3.

    We eventually decided that the 'resistor method' would be the most likely fix; and certainly the best thing to try first. For those who haven't seen the other threads, this involves bridging some of the wiring loom on the car with a resistor of a suitable value so that it thinks the airbags are present.

    After a bit of checking diagrams and discussion between us, we worked out the following...

    Each side (driver and passenger) has three wires in the plug for the seat.

    Driver:

    Yellow/Blue
    Yellow/Green
    Brown (Earth)

    Passenger:

    Yellow/Brown
    Yellow/Grey
    Brown (Earth)

    ...The Brown wire on each side does literally just go straight to earth, the remaining two feed back to the airbag controller.

    Based on that information we figured that the plan is to ignore the earth connection and bridge the other two on each side with a resistor.

    Based on previous discussion, 4.7Ω looked like the most likely value for the resistor; so ste_1210 got himself down to Maplin and picked up some resistors. He bridged the two pins in the plug with a 2W 4.7Ω resistor, and used VAG-COM to try to clear the fault code.

    ...The code cleared, the light went out! :)

    So, while some of the details may change depending upon the MY of your car, and indeed the seats (wiring colours etc.), the theory is sound and it is possible to get around this.

    I guess I have to make a disclaimer and say that if you want to try this procedure, it is of course at your own risk - especially if there are any variations on what we found; but we can say with confidence that it works - and I'm more than happy to try to help others out with any variations they may find.

    Regards,

    Rob.
     
    dirtychinchilla likes this.
  2. FactionOne

    FactionOne Administrator
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    Also, it's worth noting that if you want to avoid getting the warning light in the first place (because you don't have VAG-COM to clear it with); you can swap the seats over and install the resistor with the battery on the car disconnected.

    That way when you reconnect the battery the car will never know the difference!

    ...Remember though, you may need radio codes and similar if you disconnect the battery.

    Regards,

    Rob.
     
  3. ste_1210

    ste_1210 Member

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    id like to say a big thanks to rob for his help probly would of cut the wire on the dash if couldnt find a way around.
    and as said is tryed and tested on my own car and is working sweet
    2w resistor is needed as the lower watt resistors didnt work for some resson.
    always a good idea to insulate the resistor well incase it touches the seat and will earth it out and kick the airbag light back in which happed to me on testing you can buy the connector blocks from audi for £2 and make propper plugs which i have done saves alot off hassle and makes more dureable

    resistors can be bought from maplin for 40p

    so for less then £5 you can say bye bye to annoying airbag light

    hope this all this helps others
     
  4. FactionOne

    FactionOne Administrator
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    Teamwork mate!

    Regards,

    Rob.
     
  5. HTC

    HTC Active Member

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    I have this image in my mind with the two of you walking around the car with white coats and clip boards, discussing and recording findings.

    Nice write up, and cheers for the info.
     
  6. vwaudigroup

    vwaudigroup New Member

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    Hi,this resistor is posiblle fit to A6 4B(c5)??I swap seats and I have now diferend conectors under seats and on the seats
    airbag light is now ON
    Thank you.Mike
     
  7. Cobra88

    Cobra88 Active Member
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    Mine went straight in with no Airbag light problem.

    Guessing you mixed car & seats Pre/Post facelift ??

    I also checked wire colours first and where identical here
    but my seats are 2002 & car is 2001

    Regards
    Rick
     
  8. Chunk11

    Chunk11 New Member

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    I am attempting the resistor method to fool the airbag system in thinking that all is okay. I know in your guide that you used 2w 4.7 ohm resistors but I have only been able to get 3w 4.7 ohm resistors do you think that these will still work?
     
  9. Squirrelofdoom

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    Should still work. The resistance value is the same, just the power rating is different. Basically you'll be able to whack more current down your 3W resistor, but that shouldn't make any difference in this case
     
  10. Chunk11

    Chunk11 New Member

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    Another happy customer the 3w 4.7ohm resistors worked for me once the fault code was cleared
     
  11. dirtychinchilla

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    Hey guys,

    Just resurrecting this thread for some help. Is there any chance that someone could take a photo for me of the bridging that they've done? I don't quite understand what's meant by "bridged the two pins in the plug".
     
  12. epox

    epox Active Member

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    Think about it? What does a bridge do? Joins one side to the other....:think:
     
  13. dirtychinchilla

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    Hah yeah, I just don't want to do it wrong, though. So you literally just bend the legs of the resistor and put it in each terminal of the plug?
     
  14. epox

    epox Active Member

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    Yep
     
  15. dirtychinchilla

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    Easy peasy! Just need to source a resistor now :) and get the code reset afterwards. Thanks a lot.
     
  16. dirtychinchilla

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    Hi guys,

    Just resurrecting this thread as I haven't yet fixed my airbag light. I'm planning to do this but I'm just worried that I might plug the resistor in and the airbag will pop immediately. Is there any risk of this? I was planning just to disconnect from the battery.

    If the airbag does pop, can I just stuff it back in, or what?

    Obviously, I'm no mechanic :p
     
  17. dirtychinchilla

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    Well, I unplugged the battery and put the fuses in. I just pushed them into the holes where the wires enter the housing. I reconnected the battery (keeping out of the aim of the airbags). Unfortunately, the light is still on, but I'm optimistic that it just needs the codes reset. I'm going in to have my tyres changed tomorrow, so hopefully I can convince the chap just to reset the codes, and hopefully the airbag light will go away!
     
  18. dirtychinchilla

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    I got the codes reset today, for anyone in doubt, and the light is now gone. Thanks a million, Rob.
     
  19. dirtychinchilla

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    Guys, I've got the airbag light on but not fault codes...any ideas?
     
  20. sean_s3

    sean_s3 Member

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    Are you scanning the airbag module with vcds ? When my airbag light came on the fault code was for the drivers side igniter , fitting a new slip ring solved it.
     
  21. dirtychinchilla

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    I only have a basic diagnostic reader, so I don't think I can read the right sort of codes. I'll get the manual and have another look though
     
  22. dirtychinchilla

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    I've got an "U480 CAN-Bus OBDII OBD2 EOBD Trouble Code Read Diagnose Tester Diagnostic Scanner"
     
  23. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow...
    Staff Member Moderator Audi S3

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  24. dirtychinchilla

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    Ah man, that's annoying. Well I have no chance, and I don't own a laptop anyway so it's not like I could achieve anything with the lead.

    I'm trying to get in contact with the guy that reset them previously. Hopefully he'll get back to me and say he can do it. I don't want to hassle the guy though.

    Do you think most mechanics would mind if I dropped in just to ask them to clear my codes? Would they do it for free?
     
  25. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow...
    Staff Member Moderator Audi S3

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    Won't know until you ask one :)

    Dealer will charge you but your local garage may oblige for nothing more than beer tokens

    <tuffty/>
     
  26. dirtychinchilla

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    That is a very good point :p thanks for the advice. Hopefully They'll do it for me!

    My MOT is this weekend and I think the car is screwed. It's even more screwed if the airbag light won't turn off!
     
  27. dirtychinchilla

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    A friend is going to do it for me, thankfully. Now, it's just got to passed the damned MOT!
     

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