# update on infamous 65535 code, airbag control module



## esoxlucios (Sep 17, 2009)

I didn't find this information posted anywhere, so I thought I'd post here. This information applies to p/n 8N8-909-601 (8N8909601).

Recently, my airbag control module in my '01 TTQC, which module was replaced in 2008, failed again, and could not be reset with VCDS. I shipped it off to Airbag Systems for reflash. Came back, worked fine for a week, and went out again during a cold weather spell in Minnesota.

I spoke with Chris at Airbag systems. He said that these modules are notorious for failing during cold weather. And, I apparently had misconstrued some "instructions" he had provided with the reflashed module: 










The instructions indicated that, before reinstalling, you have to splice in a constant 12VDC to the pin shown. The receipt states that failure to do so will void the reflash warranty. Chris explained that this constant voltage is necessary because —for some unknown reason— the units are affected by extreme cold, which he said is a notorious problem that Audi has failed to address even with newer modules.

Also, although Chris is reflashing the unit as a courtesy, I did buy a new module that I read somewhere is the superseded part: 8N8-909-601-TA. I do not know whether this module is improved with regard to the cold weather problem. If anyone else knows, please post.


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## 180dan (Apr 4, 2011)

My module flips my light on when it gets below 45F. I'm in northern CA so this is about 20 nights a winter. I bought one of those ebay airbag light resetters to switch it off each time. I got a new/used module but it does the same thing(less often). So you're saying that I shouldn't keep trying new modules because the problem was never fixed? And what is the procedure for applying a contant 12v to the pin?


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## esoxlucios (Sep 17, 2009)

180dan said:


> And what is the procedure for applying a contant 12v to the pin?


Locate the wire in the wiring harness corresponding to the pin in the diagram . . . . doing so at your own risk. Splice in a constant 12VDC, such as the cigarette lighter, which is nearby. You'll need a multimeter to confirm. You can get splicing unions at RadioShack or, alternatively, expose a small amount of the wire in the harness and solder in the 12VDC constant, and then seal up with liquid electrical tape. You will be doing in this in two locations: (1) at the airbag wiring harness location; and (2) at the cigarette lighter 12VDC-constant wire location (or other suitable 12VDC wire, if you locate one different).


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## 180dan (Apr 4, 2011)

esoxlucios said:


> Locate the wire in the wiring harness corresponding to the pin in the diagram . . . . doing so at your own risk. Splice in a constant 12VDC, such as the cigarette lighter, which is nearby. You'll need a multimeter to confirm. You can get splicing unions at RadioShack or, alternatively, expose a small amount of the wire in the harness and solder in the 12VDC constant, and then seal up with liquid electrical tape. You will be doing in this in two locations: (1) at the airbag wiring harness location; and (2) at the cigarette lighter 12VDC-constant wire location (or other suitable 12VDC wire, if you locate one different).


I hate splicing into something that my life could depend on. I wonder why some modules trip at low temps and some don't. Audi really should cover this in a recall since it's so widespread. I mean, what are the odds of me having this issue then buying a used one with the exact same problem? I'll give this procedure a try soon since I have my old module laying around somewhere.


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## darrenbyrnes (Jan 4, 2005)

I always wondered why that code popped on in the cold. I also have one of those eBay resetters. Works like a charm. I guess I have another little project to do this summer...


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## esoxlucios (Sep 17, 2009)

Update:

Today, I installed the new superseded part number (8N8-909-601-TA) and followed Chris' instructions (the instruction sheet pictured in original post and the fine print on the receipt provided with the reflashed unit). It was a lot of work to locate the correct wire to splice.

_It does not work._

When 12VDC constant is supplied to that pin, the entire car turns on (like turning the key on). The blower fan comes on, the instrument cluster comes on, the radio comes on. If you were to follow those instructions without additional improvisation, your car's battery would be dead in a couple of hours. Not an ideal solution. I have no idea where he got the idea to advise customers to do this, but I will touch base with him by e-mail tomorrow.

The only thing I can think of to do, assuming that supplying that pin with 12VDC is the correct thing to do, is to install as 12VDC diode so that current cannot flow from that pin back out to the car, but can only flow in to the airbag control module, Even still, it's possible that 12VDC supplied to that pin may, in fact, activate the car's electrics by flowing back out of some other one of the control module's pins.

Another question I must now ask is whether the superseded part number (8N8-909-601-TA) actually resolves this problem, even though Chris said that Audi has yet failed to even acknowledge this issue.


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## 180dan (Apr 4, 2011)

OK, let me get this straight. You need to use the new, superseded module and tap a 12v constant? You can't even use the original module to do this? I think the way to fix this is to figure out what about temperature loss causes the problem to begin with. Does anyone have any ideas about what electronics are affected by cold temperature?


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## esoxlucios (Sep 17, 2009)

180dan said:


> OK, let me get this straight. You need to use the new, superseded module and tap a 12v constant? You can't even use the original module to do this? I think the way to fix this is to figure out what about temperature loss causes the problem to begin with. Does anyone have any ideas about what electronics are affected by cold temperature?


Here's what Chris at Airbag systems told me:



The Audi airbag control modules are notorious for failing in cold weather. He gets them returned regularly from owners in Minnesota and northern states
Audi has not yet acknowledged, let alone addressed, the problem
the control module needs a constant 12VDC to "keep it warm" (sounds implausible to me, but that's what he said)


I read somewhere that the superseded part "TA suffix" was supposed to fix the 65536 error caused by low voltage during the self-test, but I cannot find on what forum I read that.


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## esoxlucios (Sep 17, 2009)

Talked to Chris again. He said he's never heard of this issue (all the car's electrics coming on when that pin is connected to 12VDC when the car is off). He says he gets 50 to 70 Audi modules every winter (later in the call, he said "20 or 30").

I asked him how many other customers have adopted his advice, and he said lots over the last 7 or 8 years. 

He suggested cutting the preexisting 12VDC going to the airbag module (the pin identified in the OP), and instead supplying that directly from the battery (or cigarette lighter or whatever), and this will prevent the car's electrics from energizing. He said that all the other pins are solely for connection to the airbag sensors and CANBUS system (_i.e.,_ no other way to energize the car's electrics, as I was concerned about).

He said that providing a constant 12VDC to the unit keeps it warm to the touch, and seems to remedy the problem. However, he conceded that he has been unable to reproduce the problem in his workshop by putting the module in the freezer.

Here's my theory: The issue is not temperature; the issue is low voltage. It has been suggested on other threads that the 65535 error code results from low voltage when the unit is doing a self-test, and this results in writing garbage back to the EEPROM (hence, you have to ship off to Airbag Systems or other places for reflash). I had read that the superseded part (mentioned in my earlier posts) addresses this low-voltage issue (perhaps by delaying the self-test, or not running the self-test when the voltage is below _x_ — I dunno). But, when the ambient temperature is really cold (below 20° F), the output voltage of the car's battery is lower. And, it can drop down below 10.5 or even 10 during cranking. This problem is exacerbated if you have relocated the battery to the trunk area and have an insufficient gauge cable running up to the starter solenoid.

If my theory is correct, and the superseded part number addresses this low-voltage problem, then the real fix is to install the updated part, not to hack into the wiring harness and supply constant 12VDC. I wish I could say that my car would be a test of this, but sometimes these problems don't arise until years later.


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## speed51133! (Aug 5, 2002)

i live in wisconsin, and it gets below freezing almost half the year.

NEVER had this happen or heard about it....


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## 180dan (Apr 4, 2011)

Thanks for the info Esox. The funny thing is, my original module would trip my airbag all year round. As long as it got cold at night(SF nights are cold even in summer), the light would be on in the morning. When I replaced it with a used module, the light came on only after the coldest nights in winter. The battery was the same for both modules. So each module must be tripped at different voltages?


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## speed51133! (Aug 5, 2002)

San Francisco cold? Hahaha...people in Alaska have these cars...


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## esoxlucios (Sep 17, 2009)

Update to this thread. It is now one year later since I installed the 8N8-909-601-TA control module and no problems. Temps got down to -24ºF, but my car was in a garage where it was probably only down to -4ºF, and I also had the battery connected to a desulphating-type trickle charger.


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## G60DUBS (Feb 5, 2005)

I live in WI and this winter has been brutal!!  Last week when I started my 01 A4 at about -14 degrees the air bag light came on. I scanned it and got the crap 65535 code. So now i'm sourcing a used module and hopefully that doesn't already have the internal memory issue. I might wait till it warms up before installing it....who knows.


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## Aaron16V1.8l (Aug 12, 2007)

I know its not Minnesota cold, but during a recent bout of ~0 degree weather, my airbag light came on and I got the 65535 code. I installed a used module with the same coding from another TT and it seems to be working fine (the light has gone off), but it also hasn't gotten down to zero again either. If that didn't work, I was going to try the ebay tools that reflash the controller through the obd port. As the OP found though, I think the only long term solution is getting the updated module unless one can tolerate reflashing the controller every winter. Given that temps this cold are relatively rare here, I am going to see how long this used controller lasts... I really don't want to spend 600$ on an airbag controller.


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## 20v master (May 7, 2009)

I've got this issue, with controller model 8N8 909 601. When you replace the controller, is it just plug and play or do you have to code it via VAG COM?


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## Aaron16V1.8l (Aug 12, 2007)

From the research I did, this is what I learned:

- Only brand new air bag controllers can be coded with VAGCOM
- You can't change the coding of a used module with VAGCOM. 
- The modules like the model # you cited came in two flavors apparently, which are for cars with and without seatbelt indicators. This should show up as different codes when scanned by VAGCOM. I think with indicators has the workshop code 10103, and without has 10102. To have the light go out, your replacement module must have the same coding (since you can't change it). I was lucky in that the donor car was coded the same as mine so it was plug and play.


I ended up not buying it, but I have heard good things about the Ebay Chinese reset tools that reflash the controller through the OBD port - good things meaning the light goes off. How it accomplishes this I have no idea.


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## G60DUBS (Feb 5, 2005)

I did ended up buying that Ebay resetter for $37 after my orig post earlier. Seemed like maybe it was the last one . I did find a used module also but won't have that in my hands for a couple days. Hopefully it has the same part number, otherwise i'll wait for the ebay thing to show up. I'll post up again in a couple weeks when i've tried both. :thumbup:


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## 20v master (May 7, 2009)

Aaron16V1.8l said:


> From the research I did, this is what I learned:
> 
> - Only brand new air bag controllers can be coded with VAGCOM
> - You can't change the coding of a used module with VAGCOM.
> ...


There are North American TT's with and without seatbelt indicators?  I haven't removed the module from my racecar, but plan on doing that soon and hoping it works in my daily. The issue I have with the ebay reset tools is like you said: how they're turning the light off is unknown, which makes me quesetion functionality of the airbags. I don't just want the light to go off, I want the safety features designed into the car to work if I should happen to need them.


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## racin2redline (Sep 25, 2008)

^x2 and i didn't know you couldn't change the coding on the modules.. So you could potentially buy a used one with different coding and have it not work? I'd really like to fix mine. Last idiot light I have left is the airbag


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## G60DUBS (Feb 5, 2005)

Could someone with the ebay resetter and a Vag maybe confirm that after resetting the light all parts of the air bag system respond like their supposed to? I'm not going to volunteer to reset my light then crash my car to see if the bags pop


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## Aaron16V1.8l (Aug 12, 2007)

See this thread:
http://forums.vwvortex.com/showthre...ontroller-using-VCDS-pursuant-to-instructions

I was wrong in that it is the software code that is different among modules, not the workshop code. The module coding limitations still stand (you can't recode a used module). I was also partly wrong in that it is seatbelt sensors as opposed to seatbelt indicators as the source of the difference. I am not sure whether that applies to North American TTs, or whether people ran into this problem ordering used controllers from European cars and trying to install them in US versions. Again, see that thread which is also by the OP which I found when researching this problem.

I have no idea how the ebay tool works. If you use it, apparently it gets rid of the 65535 code and the light goes out. I did come across threads where people used the resetter, and after another cold snap, the light would come back on. Then they would repeat the process. To me, that suggests that the controller probably remains functional after usage of the tool, but its not going to fix the underlying cause of why it throws the 65535 code in the first place. Here is a good thread which weighs the pros and cons of using a used controller or reset tool:

http://forums.tdiclub.com/showthread.php?t=269354&page=2


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## G60DUBS (Feb 5, 2005)

Wow, some interesting comments in that 2nd link....some are pretty ignorant as far as i'm concerned, but everybody's allowed their opinion. I've had years of experience with company's that reset air bag computers and seat belts and have had almost no issues at all. Reusing a deployed air bag itself however is something that I would never do. I've seen thousands of crashed vehicles where the air bags didn't deploy. Some damage I couldn't believe the bags didn't pop, and other's where I can't believe the accident caused the bag to blow it was so minor. There's nothing at all wrong with installing used air bags and modules in other cars. I mean we are all driving around with USED air bags in our cars every day and we trust them. Sorry, that other thread got me off topic....I'm going to use that ebay resetter and not have a second thought about it :thumbup:. Eventually I'll have to replace the module because like you said, it's not really "fixing" the root problem of the corrupt memory issue I'm guessing.


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## esoxlucios (Sep 17, 2009)

20v master said:


> I've got this issue, with controller model 8N8 909 601. When you replace the controller, is it just plug and play or do you have to code it via VAG COM?


Sorry, been "out" for awhile and just saw this.

It's been a year, but my recollection was that it did need to be code with the VAG COM, by inserting a code for your model of car (tells it how many airbags, whether there's a seatbelt sensor, inter alia).


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## 180dan (Apr 4, 2011)

I use an ebay resetter each time my light comes on(about 10 times a winter) and never had any problems. I've checked for problems via vag com and the airbag module shows as having no codes. So I think the resetter is pretty safe and doing it's job. It would still be interesting to figure out what about the cold temp is making the code pop up in the first place. I like the idea of the battery voltage dropping in cold weather. But wouldn't the same thing happen when you run the battery down and can't start the car? My light didn't come on when I did this the other day and needed a jump....


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## racin2redline (Sep 25, 2008)

I wonder if this resetter would work on my allroad air suspension module -_- it's been lopsided in my driveway for a few days now


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## lite1979 (Sep 9, 2005)

I think this resetter is only for safety restraint type airbags; not stock suspension airbags. I have seen the Allroads modified with VAG-COM to have lower/higher ride height, so I would check your Allroad with a good licensed version of VAG-COM to see if there's anything you can do to remedy your situation.

Sounds to me like you have a leak in your system. Diagnose it and fix it quickly so you don't wear out the compressor.


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## G60DUBS (Feb 5, 2005)

Well my E-bay resetter came the other day and it works like a charm. Air bag light has been out ever since :thumbup:


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## ne2i (Jan 4, 2004)

which ebay reset tool did you use? 
Please provide me a link. 

Thanks!


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## lite1979 (Sep 9, 2005)

Small bump here. I still have the 65535 code, though it shows as intermittent. It really angers me that I can't get this Airbag light to go away, especially since I've never crashed the car. I was hoping after I put my glovebox back in last week that I'd be able to clear the codes, but I'm getting a "controller refused to accept code change" error in VCDS. 

Has anyone else bought a new airbag controller for his TT here? Ross-Tech says that's the only way to fix this. I think I should get a free one from Audi, since I never got to "use" the one that's in my car.


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## mugen85r (May 11, 2003)

lite1979 said:


> Small bump here. I still have the 65535 code, though it shows as intermittent. It really angers me that I can't get this Airbag light to go away, especially since I've never crashed the car. I was hoping after I put my glovebox back in last week that I'd be able to clear the codes, but I'm getting a "controller refused to accept code change" error in VCDS.
> 
> Has anyone else bought a new airbag controller for his TT here? Ross-Tech says that's the only way to fix this. I think I should get a free one from Audi, since I never got to "use" the one that's in my car.




Lite, have you got this resolved?


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## lite1979 (Sep 9, 2005)

Nope. The light is still on with the same code. Either ejg or 20v Master posted a solution to it: Buy a compatible airbag controller from Ebay and code it to match your vechicle. That's a kind of generic response, but hopefully whoever it was will chime in and give us some insight. I'd really like to have airbags in my vehicle when I drive it, and at this point, I haven't for most of the time I've owned it. Similar to other drivers, it came on one night when it was very cold out, and it hasn't gone away since.


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## 20v master (May 7, 2009)

lite1979 said:


> Nope. The light is still on with the same code. Either ejg or 20v Master posted a solution to it: Buy a compatible airbag controller from Ebay and code it to match your vechicle. That's a kind of generic response, but hopefully whoever it was will chime in and give us some insight. I'd really like to have airbags in my vehicle when I drive it, and at this point, I haven't for most of the time I've owned it. Similar to other drivers, it came on one night when it was very cold out, and it hasn't gone away since.


I didn't code anything. If the part number is the same, it'll work as is. I installed a controller from an 01 225 into another 01 225, same p/n, with no coding changes, cleared the code, and the light has been off since.


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## lite1979 (Sep 9, 2005)

Thank you, kind sir! I'll be ordering a good airbag unit for my '01 as soon as I can, then. I have VCDS, so I'll be able to clear the code (and this time it should actually go away ).


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## Wolfeie (Oct 22, 2015)

Do any of us actually know what the result of having the "Air Bag" idiot light on means? It's the only fault on my '01 180TTqc that I bought at the end of Oct, 2015. I bought one of the Chinese reset gizmos and it works just fine to extinguish the light until the next cold night - of which I get plenty.

I'd really like to know if my airbags will still work! New modules are spendy and if it will fail just the same on the next cold night, what's the point?!?

Wolfeie


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## esoxlucios (Sep 17, 2009)

esoxlucios said:


> Update to this thread. It is now one year later since I installed the 8N8-909-601-TA control module and no problems. Temps got down to -24ºF, but my car was in a garage where it was probably only down to -4ºF, and I also had the battery connected to a desulphating-type trickle charger.


Update to this thread: It has now been three (3) years since I installed the superseded control module with low temps as described in my Jan-2014 post, above, and I have had no problems. I even had a battery fail during that time (thus, causing very low voltage and cold weather, combined). The fix appears to be getting the newer module, and not splicing wires, or purchasing eBay reset kits, or any other weirdness.


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## lite1979 (Sep 9, 2005)

It's an internal memory fault most of the time. Sometimes, it's on because you disconnected a component of the system (seat, steering wheel, glovebox) and have to reset it with the appropriate software. In my case, resetting the code has not made it go away, and my airbags won't work until I source a replacement controller. The point is not to have severe head trauma, and that's worth a lot to me.


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## Usmcff1985 (Jun 1, 2016)

Just had this same code pop up on my Audi TT 01. Like many others the code came on during a cold winter day. I purchased a $20 VW/Audi airbag reset tool on ebay ebay. Light gone. I tried 3 other Vag obd tools ranging from $60 to $450 and the $20 tool works!


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## abacorrado (Apr 5, 2005)

Usmcff1985 said:


> Just had this same code pop up on my Audi TT 01. Like many others the code came on during a cold winter day. I purchased a $20 VW/Audi airbag reset tool on ebay ebay. Light gone. I tried 3 other Vag obd tools ranging from $60 to $450 and the $20 tool works!


 Could you post a link to said ebay tool?


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