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Andrew1971

My little accident with me lupo

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How annoying is this. If only I knew this earlier when I had the whole dash board off. 

Due to passenger air bag. I take it i am the only one this has happened to on this forum.

Andrew 

If this is not a single use ecu then do I need to remove it. Unless I disturbed the wiring to it.

Edited by Andrew1971

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I've also heard that it's a one hit wonder... have no proof of this though. Something to do with super capacitors and charge retention once the battery has been ripped out during the crash process. The airbag still needs power even if there's no engine or battery to ignite it...  easiest is to try swapping them over to eliminate a loom fault. But like @Rich says, it's a right pain to get to. I've never needed to. Ever.

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3 hours ago, mk2 said:

I've also heard that it's a one hit wonder... have no proof of this though. Something to do with super capacitors and charge retention once the battery has been ripped out during the crash process. The airbag still needs power even if there's no engine or battery to ignite it...  easiest is to try swapping them over to eliminate a loom fault. But like @Rich says, it's a right pain to get to. I've never needed to. Ever.

What about if you disconnect the airbag itself??

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Assuming the Gti shares the same mounting position - my stripped lupo come in handy - its not that buried, only slightly further forward than the clutch pedal:

4n5wKP.jpg

Please ignore the dust.. HTH

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14 hours ago, Skezza said:

What about if you disconnect the airbag itself??

That won't make any difference as the airbag hasn't been ignited. I think it's to ensure the car is effectively reset with a new ecu, so if the worst was to happen again, all the airbags would deploy correctly. I will double-check this but I'm 99% certain the airbag ecu is a one-use only affair and needs to be replaced if an airbag goes off.

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22 hours ago, lupogtiboy said:

That won't make any difference as the airbag hasn't been ignited. I think it's to ensure the car is effectively reset with a new ecu, so if the worst was to happen again, all the airbags would deploy correctly. I will double-check this but I'm 99% certain the airbag ecu is a one-use only affair and needs to be replaced if an airbag goes off.

My point is: @mk2 suggested it was to do with maintaining a current into the airbag itself, even when there is no connection to the battery. Disconnect the airbag? What about when a car is left for 2 years and the battery dies?.... unless the airbag has super caps as well? However super caps maintain charge for a limited period of time. They're not batteries..... So they would eventually die as well.

It seems very strange to me. Perhaps it's my software engineering background, but software is software..... it doesn't change when it feels like it. Lines of code. Hence why I am asking if the reasons they're one-hit are hardware based? Physical limitations..... Perhaps there's a tiny little jump pack or something that shoots a higher than average voltage??? However from my 30 seconds on Google, I'm reading that an airbag can actually be deployed with significantly less than 12v, so it doesn't appear to be that either. It almost sounds like a simple transistor would suffice the actual task of deployment. I just wonder if we dismantled a good module and a 'used' module, whether there would be any actual difference. If not, then it's just an EEPROM right? A software 'fuse'. Flash the original EEPROM using the many many tools available. Module fixed? I'm almost tempted to try it in the name of science. I'm sure I could find a knackered old Lupo with a blown or belching engine, backup the EEPROM, run it into a wall, reload the backup after changing the airbags, see what happens.

Of course, I'm not recommending ANY of this, including the flashing of the EEPROM's etc. I'm just keen to know exactly why they're one hit? If it's just to 'ensure consistency' or reliability then why not just have every unit one hit, especially safety units? Hopefully someone less cynical than me will explain that there's a scientific reason and not because VW fancied cashing in on cars that had been in a crash.

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Is it worth taking a punt with your safety by using an airbag module that has deployed and may not fire the airbags again in the event of a crash? I value my life so despite the costs involved in replacing the controller, I value being alive a lot more than the money it costs. Plus if I had passengers in the car and they failed to go off and I knew it was a controller that had already been involved in an accident and may not work, how would you feel? Guilty as sin I'd hope. But hey, it's your life, if you want to risk it with something that's already done its job then go ahead. And lets not forget that the airbags could deploy without being in an accident, have you seen an airbag go off? By the time your face hits it, the airbag is already deflating so as not to cause more harm than good, so being hit in the face by an airbag going off when it shouldn't be can cause all sorts of problems, not least to say some pretty serious burn marks on skin.

Oh and another thing, people seem to blame VW for designing the safety systems they use in their cars, I'm pretty sure like most manufacturers they use companies that specialise in these things and their are made to the specifications that the manufacturer wants. 

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Most airbag controllers contain an electromechanical G-force sensor that is a "one time use" sensor. Once it has experienced enough G-force to deploy the bags, the behavior of this sensor is unpredictable at best. In other words, VW does not make the "Crash Data Stored" code unclearable via the normal diagnostic API simply because they want to sell more airbag modules.

This was the answer I was looking for. No need for my experiment now and considering the forces that can be exerted in an accident, I suspect only the most trivial of accidents would avoid damaging this sensor.

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2 hours ago, lupogtiboy said:

Is it worth taking a punt with your safety by using an airbag module that has deployed and may not fire the airbags again in the event of a crash? I value my life so despite the costs involved in replacing the controller, I value being alive a lot more than the money it costs. Plus if I had passengers in the car and they failed to go off and I knew it was a controller that had already been involved in an accident and may not work, how would you feel? Guilty as sin I'd hope. But hey, it's your life, if you want to risk it with something that's already done its job then go ahead. And lets not forget that the airbags could deploy without being in an accident, have you seen an airbag go off? By the time your face hits it, the airbag is already deflating so as not to cause more harm than good, so being hit in the face by an airbag going off when it shouldn't be can cause all sorts of problems, not least to say some pretty serious burn marks on skin.

Oh and another thing, people seem to blame VW for designing the safety systems they use in their cars, I'm pretty sure like most manufacturers they use companies that specialise in these things and their are made to the specifications that the manufacturer wants. 

I wasn't having a go and I am certainly not putting a price on life..... although considering you live in a country where only the wealthiest in society (or tax funded aristocrats) get the best healthcare, there is a fairly strong argument for some life being more valuable than others. Seems to depend whether you're someone special or not. Sorry if that sounds all a bit socialist'y.

I wanted to know if there was a scientific reason. It's all well and good saying "I value life a lot more than money", well for some that depends on whether the difference between them and a homeless man is their job, right? I will openly admit, and I shouldn't because we're supposed to encourage good behaviour, but I will openly admit to driving around a few years ago with a resistor behind my cowling because the clock spring on my red Lupo had gone. This was before the cheap Chinese knockoffs were popping up and an OEM clock spring was more expensive than I expected. I subsequently repaired the OEM one, at some effort with a soldering iron and my sanity. Would that be considered safe? Now you can get a cheap one for less than the cost of 2 pints of beer. 

I was keen to know if it was purely a software fuse or if there was some valid science behind this. I write software, therefore I have seen some oily tricks that I don't consider remotely ethical. Planned obsolescence. There's a G-Sensor built-in to the module (bad design imo, but we can gloss over that). Once that G-Sensor has been tripped, a certain amount of force has already been exerted on it. The sensor is now unreliable or perhaps unpredictable............ OR, it's completely fine and designed to survive multiple accidents, however, like you said, it is not worth taking the risk with something designed to mechanically detect an impact or not. I would totally agree with that. There clearly is valid science here.... and that's all I was asking.

Like I said, wasn't having a go..... it's a good debate and now the debate has been concluded by the thread posted above.

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Skezza, I wasn't having a go at you or anyone else, it's like this as it's a safety-related item. I've never taken one apart to see what they are like inside, if I get the chance then I will. The quote above boils my blood a bit as they are blaming VW for not being able to have this module reset, I'm sure that it's not by VW's design but the company that makes them for VW. Yes I'm sure there are parts that are built to fail, but generally not safety related parts that are there to save your life, not work for 5 years then stop, or we'd all be buying seat belts and airbags every other year.

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The sensor to the best of my knowledge is a semiconductor accelerometer, usually manufactured by Analog Devices. So think playstation controller sensor that can tell which way you're moving it... they are very tough little buggers. Surprisingly accurate too. But the way the crash sensor works is not by G-force. They actually 'listen' to the shock waves that are generated as the vehicle crumples. The activation pulse is only generated by the controller when it recognises an appropriate shape or waveform. The waveforms are characterised during trial crumples... Then a DSP chip does the recognition. It's a fair bit more complex than a simple g sensor.

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Hi All

Thank you all for the replys. I am tempted to get an air bag ecu from eBay but would it work as it 

should. I am getting to the stage of being not worth it. I got a little thinking of what to do.

Andrew

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9 hours ago, lupogtiboy said:

Skezza, I wasn't having a go at you or anyone else, it's like this as it's a safety-related item. I've never taken one apart to see what they are like inside, if I get the chance then I will. The quote above boils my blood a bit as they are blaming VW for not being able to have this module reset, I'm sure that it's not by VW's design but the company that makes them for VW. Yes I'm sure there are parts that are built to fail, but generally not safety related parts that are there to save your life, not work for 5 years then stop, or we'd all be buying seat belts and airbags every other year.

The reason I continue to buy VW and decided not to buy another BMW is the exact opposite of that. I've always found VWs are indeed built to last. Both my Lupos lasted like absolute warriors. I've never found a part that seemed designed or destined to fail, like on certain other brands. There's planned obsolescence and there's simply poor design. The second is forgivable..... but I've only ever driven old VWs so no opinion on new ones. 08 is the newest, that's ancient these days really.

Trust me, I continue to root for VAG all the way. Didn't buy a second A4 for nothing.

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46 minutes ago, Andrew1971 said:

Is the air bag ecu the same in every model of lupo.

Andrew

I would have thought so.

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