Wanted: Airbag Module
#16
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10 years ago Toyota used a stored gas inflator. To describe function, think of a co2 cartridge with a bb shot welded into the neck of the cartridge to maintain pressure. These inflators have an acceptable leak % and after 10 years it may or could be below what they consider acceptable. Here's the smoke and mirror, these inflators are within the chamber and even if they could remove it for inspection, they do not have the equipment or time at ANY deal or service provider to check for pressure so they will automatically suggest replacement. They would have to send it back to the manufacturer (TRW, Takata, Daicel,) to release all the gas and refill them to check for leaks. Now think back to the sigma rate I gave in my earlier and determine probability of failure in your car. Airbags evolve and each manufacturer uses different methods for inflation (stored gas, MGG, pyrotechnic) but the reality is the "inspection" is nothing more then checking the standard diagnostics (electrical) that you get though the idiot light and a recommendation for inflator replacement after the interval suggested by the engineering group. Find me an ASE tech that knows how to inspect an inflator or initiator and I'll show you a liar.
So rough numbers here..........99.99999999% probability a disconnected airbag system won't fire vs a 99.99% probability that a connected old system will fire. I'm going with the latter.
Funny thing, I don't have an airbag in my 951. It's amazing the **** you can pick up on How It's Made huh? LOL.....
Last edited by Jeremy Himsel; 12-18-2008 at 07:37 PM.
#18
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Basically, they do that for a release of liability and to a small degree revenue. That way if there is a problem....it's because you didn't do something that they recommended. Each manufacturer has an "inspection time span" and the number is derived based upon a few factors. Toyota is a great example to use and there is a bit of smoke and mirrors to it.
10 years ago Toyota used a stored gas inflator. To describe function, think of a co2 cartridge with a bb shot welded into the neck of the cartridge to maintain pressure. These inflators have an acceptable leak % and after 10 years it may or could be below what they consider acceptable. Here's the smoke and mirror, these inflators are within the chamber and even if they could remove it for inspection, they do not have the equipment or time at ANY deal or service provider to check for pressure so they will automatically suggest replacement. They would have to send it back to the manufacturer (TRW, Takata, Daicel,) to release all the gas and refill them to check for leaks. Now think back to the sigma rate I gave in my earlier and determine probability of failure in your car. Airbags evolve and each manufacturer uses different methods for inflation (stored gas, MGG, pyrotechnic) but the reality is the "inspection" is nothing more then checking the standard diagnostics (electrical) that you get though the idiot light and a recommendation for inflator replacement after the interval suggested by the engineering group. Find me an ASE tech that knows how to inspect an inflator or initiator and I'll show you a liar.
So rough numbers here..........99.99999999% probability a disconnected airbag system won't fire vs a 99.99% probability that a connected old system will fire. I'm going with the latter.
Funny thing, I don't have an airbag in my 951. It's amazing the **** you can pick up on How It's Made huh? LOL.....
10 years ago Toyota used a stored gas inflator. To describe function, think of a co2 cartridge with a bb shot welded into the neck of the cartridge to maintain pressure. These inflators have an acceptable leak % and after 10 years it may or could be below what they consider acceptable. Here's the smoke and mirror, these inflators are within the chamber and even if they could remove it for inspection, they do not have the equipment or time at ANY deal or service provider to check for pressure so they will automatically suggest replacement. They would have to send it back to the manufacturer (TRW, Takata, Daicel,) to release all the gas and refill them to check for leaks. Now think back to the sigma rate I gave in my earlier and determine probability of failure in your car. Airbags evolve and each manufacturer uses different methods for inflation (stored gas, MGG, pyrotechnic) but the reality is the "inspection" is nothing more then checking the standard diagnostics (electrical) that you get though the idiot light and a recommendation for inflator replacement after the interval suggested by the engineering group. Find me an ASE tech that knows how to inspect an inflator or initiator and I'll show you a liar.
So rough numbers here..........99.99999999% probability a disconnected airbag system won't fire vs a 99.99% probability that a connected old system will fire. I'm going with the latter.
Funny thing, I don't have an airbag in my 951. It's amazing the **** you can pick up on How It's Made huh? LOL.....
I have many left over airbags from 80s Mercedes and BMWs in my shop, I am definately trying to ignite them in the yard, Mythbusters style
#19
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There is very little reason (from a safety perspective) to pull or disconnect the airbags in our cars. The Airbags in our cars really have a bad rap for no real reason. The first is usually......the older bags hit so hard that they'll kill you and the second is .......the age of the system won't allow it to inflate.....I'll try and debunk them briefly without going too geek. Also, to be quite honest an ASE certified mechanic has no clue how an air bag really operates and many of them (not all) are parts changers not system experts or critical thinking diagnostic guru's. If one of the most critical safety components on a car REALLY had a service life of 15 years so many law suits over it you wouldn't be able to buy a used car without a waiver releasing responsibility from the manufacturer in the US. I probably wouldn;t have a job right now either. It's like saying that 15 year old brake hoses (much more delicate from a materials and exposure perspective then an air bag system) won't last that long. It is however a good "safe guard" recommendation to reduce liability. Reason being is that the propellants can degrade over time due to exposure but with the exception of some very early plastic and non-sealed initiators (not in our cars) they are all hermetically sealed which prevents exposure and ultimatly degredation. If the propellant components were under your hood then I'd be inclined be concerned but they're not.
Reality is the first generation air bag systems (early 80's) have a sigma rating in the Σ 5.6 to 5.7 range and have improved since then. The component in an airbag system that is most vulnerable to failure is the wiring in the engine compartment (virtually everything else in the system is sealed). This wiring sees the same exposure (less actually) as your headlights, fan switch, engine harness, etc. Now, take voltage meter to your headlight harness and alternator/battery. You'll probably see about 12.5 at the battery and around 10ish at the lights. So after 20 years of corrosion, heat, and general exposure (along with standard drops based on wire gauge and length) you have a voltage drop of about 20%. Let's say triple the same drop exists in the air bag wiring system (extreme example) and you only have about 4.5V going through the wiring, module, and to the initiator. It sounds bad, but automotive initiator manufacturers build them to fire at a minimum of 1.2V......meaning they account for that stuff and unless you have a car that is an electrical nightmare and severely damaged it won't be an issue. Basically, there are a lot of other electrical components that will flat out not operate before an air bag system so if your not getting a fault on the start-up self diagnostic test, I wouldn't worry about about it because you have a better chance of hitting the lotto then having propellant issues.
Let's talk about the SRS or control module. Just because it has a fault does not mean it won't work despite what the idiot gauge tells you. It MAY not work or be working at optimal conditions but it doesn't mean it's bad. Think of it like an air pressure warning system on your car. The pressure may be a bit low (due to leaks, temperature, whatever) but it doesn't mean you have a flat. In this case, the voltage may be a bit low, but not enough to prevent operation. What it tells you is that something isn't functioning at optimal conditions and you should have it looked at. Even though a ZPP initiator will fire @ 1.2V, the system still wants to see max voltage and not rely on the built in safety of the unit. If you still have the original coil, S&R sensors, DME & KLR, and transmission back up sensor (which all see "severe" conditions") that work I wouldn't be overly concerned with an airbag control module that not only has a higher build standard then the rest of the car's components, but it secured tightly in a dry and secure location. Now if the airbag warning light in your car is flashing then I would have it serviced but it is simply not even reasonable to pull the unit based upon the perception of failure.......or worse......what you read on Rennlist.
Now the second item that people pull the bags for is airbag force. The original airbag systems were single initiator-single inflator systems that packed a lot of punch. The crash requirements back then were for a full sized occupant to survive a 30mph unbelted head on collision. In order to meet these requirements the original bags packed a hell of a punch to keep the fat asses in their cars and to not overpower the airbag. After a bunch of small people (kids and women) not wearing seatbelts were getting seriously jacked up they changed the requirements. Nowadays the newer airbags have belted 30mph requirements so the inflators are not as violent and many cars have seat sensors to determine occupant size and have variable initiator and inflator firing capability. Most cars now have dual initiator airbags. I will say that unless your a 80 lb unbelted occupant, it's probably safer to leave the bags in and operational. If your concerned about the punch of the bag or have a small kit in the car, follow the recommendations on your newer car and have the seat as far away from the dash as possible. The service life for modern initiators and inflators are over 100 years and "MOST" of the older systems are not far behind.
So if that's enough reason to put your air bag back in then I'm glad I could help. If not and it's going to sit on a shelf, grab a video camera, dig a two foot hole in your yard or an open field if your yard is too small, place the airbag in the hole (electrical connector up), grab about 2 50' lengths of wire connected to the leads on the bag, stand back about 30' and connect the other end to a lantern battey and laugh your *** off. If it doesn't fire send me the complete video of it not working and I'll send you $50.
And oh yeah, as far as the it's expensive to replace the dash if one blows comment.......If you hit something hard enough to pop a bag in a 951, you got bigger **** to worry about then the dash.
Reality is the first generation air bag systems (early 80's) have a sigma rating in the Σ 5.6 to 5.7 range and have improved since then. The component in an airbag system that is most vulnerable to failure is the wiring in the engine compartment (virtually everything else in the system is sealed). This wiring sees the same exposure (less actually) as your headlights, fan switch, engine harness, etc. Now, take voltage meter to your headlight harness and alternator/battery. You'll probably see about 12.5 at the battery and around 10ish at the lights. So after 20 years of corrosion, heat, and general exposure (along with standard drops based on wire gauge and length) you have a voltage drop of about 20%. Let's say triple the same drop exists in the air bag wiring system (extreme example) and you only have about 4.5V going through the wiring, module, and to the initiator. It sounds bad, but automotive initiator manufacturers build them to fire at a minimum of 1.2V......meaning they account for that stuff and unless you have a car that is an electrical nightmare and severely damaged it won't be an issue. Basically, there are a lot of other electrical components that will flat out not operate before an air bag system so if your not getting a fault on the start-up self diagnostic test, I wouldn't worry about about it because you have a better chance of hitting the lotto then having propellant issues.
Let's talk about the SRS or control module. Just because it has a fault does not mean it won't work despite what the idiot gauge tells you. It MAY not work or be working at optimal conditions but it doesn't mean it's bad. Think of it like an air pressure warning system on your car. The pressure may be a bit low (due to leaks, temperature, whatever) but it doesn't mean you have a flat. In this case, the voltage may be a bit low, but not enough to prevent operation. What it tells you is that something isn't functioning at optimal conditions and you should have it looked at. Even though a ZPP initiator will fire @ 1.2V, the system still wants to see max voltage and not rely on the built in safety of the unit. If you still have the original coil, S&R sensors, DME & KLR, and transmission back up sensor (which all see "severe" conditions") that work I wouldn't be overly concerned with an airbag control module that not only has a higher build standard then the rest of the car's components, but it secured tightly in a dry and secure location. Now if the airbag warning light in your car is flashing then I would have it serviced but it is simply not even reasonable to pull the unit based upon the perception of failure.......or worse......what you read on Rennlist.
Now the second item that people pull the bags for is airbag force. The original airbag systems were single initiator-single inflator systems that packed a lot of punch. The crash requirements back then were for a full sized occupant to survive a 30mph unbelted head on collision. In order to meet these requirements the original bags packed a hell of a punch to keep the fat asses in their cars and to not overpower the airbag. After a bunch of small people (kids and women) not wearing seatbelts were getting seriously jacked up they changed the requirements. Nowadays the newer airbags have belted 30mph requirements so the inflators are not as violent and many cars have seat sensors to determine occupant size and have variable initiator and inflator firing capability. Most cars now have dual initiator airbags. I will say that unless your a 80 lb unbelted occupant, it's probably safer to leave the bags in and operational. If your concerned about the punch of the bag or have a small kit in the car, follow the recommendations on your newer car and have the seat as far away from the dash as possible. The service life for modern initiators and inflators are over 100 years and "MOST" of the older systems are not far behind.
So if that's enough reason to put your air bag back in then I'm glad I could help. If not and it's going to sit on a shelf, grab a video camera, dig a two foot hole in your yard or an open field if your yard is too small, place the airbag in the hole (electrical connector up), grab about 2 50' lengths of wire connected to the leads on the bag, stand back about 30' and connect the other end to a lantern battey and laugh your *** off. If it doesn't fire send me the complete video of it not working and I'll send you $50.
And oh yeah, as far as the it's expensive to replace the dash if one blows comment.......If you hit something hard enough to pop a bag in a 951, you got bigger **** to worry about then the dash.
In posting and reading over this thread what you said here is pretty much what was going through my mind. If your in a bad enough accident that it goes off, your probably not repairing your car and since you not brain dead, thank yourself for NOT removing the airbag.
So the bag might hit someones face hard and brake thier nose, chip a tooth, or even if it broke thier jaw....the person would recover. What do you think would happen to a person who removed thier airbag so thier head hit the steering wheel or dashboard with the same force.
I removed mine because I have 6pt harnesses and I'm adding a full welded in cage. For a stock 944, it's just plain stupid to remove a perfectly good airbag system.
I'm not going to waste a perfectly good steering wheel by setting it off in my backyard either...because I already know it WILL still be functional.
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#23
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I can believe the bag will last that long , the electronics is something else........
#24
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Bee Jaysus Jeremy thanks for that masterclass on airbags..... They say that everyday is a school day ...!
The blink fault code in Clarkes Garage says that my drivers side ignition pill is open circuit. Id say that means a new steering wheel unit (in brown) along with the Control unit..
I'll have to keep an eye out for them parts......!
Thanks again gents.....!
Dont forget to PM me if you are coming over to Ireland....
The blink fault code in Clarkes Garage says that my drivers side ignition pill is open circuit. Id say that means a new steering wheel unit (in brown) along with the Control unit..
I'll have to keep an eye out for them parts......!
Thanks again gents.....!
Dont forget to PM me if you are coming over to Ireland....
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#25
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I had the same code and it turned out to be the slip ring (clock spring in BMW speak...or maybe it's the other way around). New one wasn't too bad pricewise from the dealer.
#26
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What was the price on a new one? My clock spring is showing a short right now. I plan to bring it inside in the spring and check it over for any pinched wires (since there is a harness on each side of it) but I suspect it is damaged inside somehow from my playing with it. Couldn't resist the urge to repeatedly spin it back and forth while it was off the car.
#28
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Sorry to drag this post up again chaps.. but I sorted out both the airbag issues. I managed to get an airbag control module off eBay for about €40 (seller hadnt a clue what it was for...!) I also got the afforementioned clock spring for the driverside airbag off our OPC Agnews in Belfast for about €85. I replaced the bulbs in the instrument cluster and now all is well....!
Thanks very much for your help lads and the bonus is I got educated as well....! Hopefully now I wont be needing them to deploy.......!
Thanks very much for your help lads and the bonus is I got educated as well....! Hopefully now I wont be needing them to deploy.......!