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D2 - Interior Electrics Airbags, Sensors, climate modules, instrument clusters, switches etc

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  #1  
Old 24th January 2009, 10:49 PM
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Default Airbag warning light - Passenger seat

Here is another very common fault, which seems to hit many D2's with the sports recaros after around 10 to 12 years of life, although it will certainly be based on the number of time the passenger seat is used.

How to diagnose:

The fault is diagnosed using vagcom on the Airbag controller, and expect to see a fault regarding the 'seat occupancy sensor' for the front passenger seat. It will likely be 'intermittent'

You can reset the fault, but it *will* reoccur, it might be a week, it might be a month, but it will.

What is the sensor for ?

The occupancy sensor is used to determine whether anyone is sat in a particular seat. The theory is, that if a seat is unoccupied, then in a crash it can deploy less airbags and reduce the repair cost. There is always a sensor on the passenger seat, and apart from the very early D2's, and the very last ones, there are two sensors for the rear seats too. The drivers seat has no sensor as its fair to assume in a crash that seat was occupied

Where is it?

The occupancy sensor is actually nothing more than a thin, flimsy pressure pad that is bonded on the seat foam underneath the seat covering. It is not a mecanical switch or push to make type contact, instead it is a pressure pad which gives a variable resistance depending on the load on the seat.

Does it affect non sports seats?

No, it doesnt seem to. The sports seats are unique in that the presssure pad is in two parts - It has one part on the main seat base, and another much smaller one on the pullout knee squab. It is this latter one that always seems to fail.

Can I just bypass it ?

Yes, See below

How can I fix it Properly?

The pressure pad is bonded onto the heated foam of the sports seat, and thus the whole item needs replacing. The part is approximately £200 from Audi. Expect to pay 2 / 3 hours labour to have it fitted.

Depending on how long you intend to keep the car, it may be cheaper and more cost effective to consider just buying a 2nd hand passenger seat without the fault. Check with us to see what stock we have.
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  #2  
Old 7th February 2009, 03:54 PM
sutherland sutherland is offline
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Quote:
Originally Posted by Ian@A8Parts View Post
Can I just bypass it ?

No, because it generates a variable resistance and not just a simple short to ground, its just not that simple.
Surely someone can up with a bypass schematic that can be built and plug in under the seat. I see folk have done this for BMWs. I imagine that when the seat is being sat upon it creates a steady resistance or a resistance above a certain point that can be permanently replicated.

Can you advise which plug it us under the seat?
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Old 7th February 2009, 09:01 PM
PsYcHe PsYcHe is offline
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Interestingly enough.. Mine used to do this all the time '98 with Sports seats.

Had the ECUs disconnected when trying to get to the source of a leak, and also tightened the connections on the airbag ECU behind the centre console and it hasn't came back again.

Maybe just got lucky, but might be worth looking at the ECU connections to make sure they haven't worked loose. Are there extra wires to the sensor in the sports seats?
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Old 7th February 2009, 09:10 PM
Simon Wallwork Simon Wallwork is offline
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My 97 A8 has this snag. I've thought of taking the bulb out, but that's not really my style!

I'll have a shot at the connectors, Psyche, but surely all that's needed is to convince the car that the passenger seat is permanantly occupied?

Surely this could be done by shorting a couple of wires with a jumper?

Failing that, how to reset the system?

Ta
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Old 7th February 2009, 10:19 PM
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You can reset the airbag light using VAG COM, have done this. But it just comes back on
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Old 8th February 2009, 08:55 AM
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Its not a simple make or break connection, its a resistance value that determines whethe its occupied or not....

I do agree that it should be possible generate a fake resistance equal to the airbag sensor mat -

There is a unit available for BMW's that does just that, and I bought one last week so when I get chance to test it, i'll let you know.

The correct values for the pressure mat are well documented, so if someone is really handy with their electronics and can knock up the right resistance we may be on a winner... I'm ok with electronics, but draw the line at trying to make any sort of circuit that looks professional
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For parts enquiries and Forum User Administration please contact customer services directly, not me - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537

The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones.

The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff......

The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous.....

The First 20 Audis:

2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey,
2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue,
2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue,
2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey,
2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6,

The Second 20 Audis:

2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue,
2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black , 2007 TT Roadster,
2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black,
2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi)
2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black

Most Recent Audis:

2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8

Everything Else

1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
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