air bag reset

carlberry64 · Post by **carlberry64** » 22 Mar 2010, 22:12

hi
i am re building the front end of my 2006 C5 as it had front end smash.
the drivers steering wheel airbag deployed.
i have replaced this and still get a fault warning saying
airbag/seatbelt fault
does this have to be reset and if so how do i if possable do it.
thanks

addo · Post by **addo** » 22 Mar 2010, 23:26

The airbag controller unit has to be removed, its stored data cleared and then it needs reinstalling.

I CANNOT speak for later than 2001 cars, but have dissected a couple of airbag controllers now and want to make the following clear (because there is an unbelievable amount of hysteria and misinformation around)...

When the airbags or pretensioners go off, the physical processes which occur in the airbag controller are wholly repeatable. A little ball shoots along a plastic tunnel against spring force. If it goes hard enough, electrical contacts are bridged and stuff happens like seatbelt pretensioners firing (bet yours have gone off - please check) and airbags deploying. At the same time, a whole bunch of current and very recent data is "frozen" into the airbag computer.

Nothing is broken, or spent up, other than the airbags/pretensioners.

I personally would have 100% confidence in a third party "reset" of a used controller, in terms of it working fully in another crash. Again, I restate this is a personal opinion.

You might try "Tachosoft" or "airbagreset" for the apropriate service.

Regards, Adam.

carlberry64 · Post by **carlberry64** » 23 Mar 2010, 08:48

addo wrote:The airbag controller unit has to be removed, its stored data cleared and then it needs reinstalling.

I CANNOT speak for later than 2001 cars, but have dissected a couple of airbag controllers now and want to make the following clear (because there is an unbelievable amount of hysteria and misinformation around)...

When the airbags or pretensioners go off, the physical processes which occur in the airbag controller are wholly repeatable. A little ball shoots along a plastic tunnel against spring force. If it goes hard enough, electrical contacts are bridged and stuff happens like seatbelt pretensioners firing (bet yours have gone off - please check) and airbags deploying. At the same time, a whole bunch of current and very recent data is "frozen" into the airbag computer.

Nothing is broken, or spent up, other than the airbags/pretensioners.

I personally would have 100% confidence in a third party "reset" of a used controller, in terms of it working fully in another crash. Again, I restate this is a personal opinion.

You might try "Tachosoft" or "airbagreset" for the apropriate service.

Regards, Adam.

hi adam thanks for the reply, how can i tell if the seatbelt pretensioners firing has accured? also where will i find the airbag controller do i just need it resetting or can i just get one from the breakers yard and replace.

thanks

addo · Post by **addo** » 23 Mar 2010, 10:00

If the seatbelts have pretensioners, they may be in the buckle stalks - look for a wrinkled or distorted stalk. If the pretensioner is at the reel end, it usually damages the plastic B pillar mould with explosive force. By the parts diagrams, I think it's at the bottom of the B pillar; maybe under the carpet. Look for a reel that doesn't retract properly anymore, or an odd wrinkle in the belt near its anchoring end.

An educated guess puts the control module in your centre console, just forward of the gear lever. Treat it gently at all times, and leave the battery disconnected for at least 15 minutes before tinkering with it. It is best generally to either buy a new one and have it configured to your car's body computer, or to reset the old one. I'm not sure that plugging in a unit off a scrapped car will work.

wheeler · Post by **wheeler** » 23 Mar 2010, 10:43

On a C5 the pre-tensioners are in the inertia reels but on a mk2 C5 (which i assume this is due to it being a 2006 model ?) there is also an extra pyrotechnic pre-tensioner on the passenger side only lap part of the belt where it bolts to the floor.
I dont see a problem with using a 2nd hand ECU as i dont think they are VIN coded, the other features (knee & curtain airbags etc) can be re-configured with lexia to match whats fitted to the car, aslo the ECU is indeed under the centre console.
It would have to be from a mk2 though as a mk1 is completely different, the only problem i can see with that is whats the chances of finding a mk2 C5 in a breakers that hasnt been smashed ?

Post by **Paul-R** » 23 Mar 2010, 11:56

addo wrote:Look for a reel that doesn't retract properly anymore,

That would surely describe every C5 built? There are many posts on this C5 "feature" so I don't think you can use that as an identifier.

carlberry64 · Post by **carlberry64** » 23 Mar 2010, 11:57

wheeler wrote:On a C5 the pre-tensioners are in the inertia reels but on a mk2 C5 (which i assume this is due to it being a 2006 model ?) there is also an extra pyrotechnic pre-tensioner on the passenger side only lap part of the belt where it bolts to the floor.
I dont see a problem with using a 2nd hand ECU as i dont think they are VIN coded, the other features (knee & curtain airbags etc) can be re-configured with lexia to match whats fitted to the car, aslo the ECU is indeed under the centre console.
It would have to be from a mk2 though as a mk1 is completely different, the only problem i can see with that is whats the chances of finding a mk2 C5 in a breakers that hasnt been smashed ?

hi wheeler thanks for that.
your right there is no chance of finding one as i spent the best part of 2 days searching the net and phoneing aroung loads of breakers.

this extra pyrotecechnic pre-tentioner would this also cause the airbag/belt fault indicator.

Also when i pull the passengers seat belt it makes a clicking sound would this indicate the pre-tentioners has gone off.

thanks

falling-out-with-my-car · Post by **falling-out-with-my-car** » 23 Mar 2010, 17:33

the air/bag light may be flashing due to the fact that the steering wheel has at some point been removed and the airbag electrical wiring cassette that goes around the steering colunm has been fractured these cost around £80 to buy new.

I couldnt find all of my airbag faults and wanted them turned off. fortunately someone on here found a way and the airbag everlasting bulb went out for good.

addo · Post by **addo** » 23 Mar 2010, 18:45

Carl, I suspect the C5 is "clever" enough that it would only set off the seat belt pretensioners for a passenger if there is one in the car. After all, it didn't fire the passenger airbag.

However, I cannot be sure as it will possibly be a good few years before I actually work on a facelift C5!

To note generally - when a reel pretensioner fires, it often locks the reel, so in addition to not retracting, it won't extend.

carlberry64 · Post by **carlberry64** » 23 Mar 2010, 19:01

falling-out-with-my-car wrote:the air/bag light may be flashing due to the fact that the steering wheel has at some point been removed and the airbag electrical wiring cassette that goes around the steering colunm has been fractured these cost around £80 to buy new.

I couldnt find all of my airbag faults and wanted them turned off. fortunately someone on here found a way and the airbag everlasting bulb went out for good.

hi falling-out-with-my-car

Its not the airbag light that goes out after a few seconds as it should,
its in the display on the dash in the centre that gives the indication airbag/seatbelt fault.
i replaced the drivers air bag and still get the fault.
thanks

carlberry64 · Post by **carlberry64** » 23 Mar 2010, 19:04

addo wrote:Carl, I suspect the C5 is "clever" enough that it would only set off the seat belt pretensioners for a passenger if there is one in the car. After all, it didn't fire the passenger airbag.

However, I cannot be sure as it will possibly be a good few years before I actually work on a facelift C5!

To note generally - when a reel pretensioner fires, it often locks the reel, so in addition to not retracting, it won't extend.

hi addo
ye i thought that, think it must be the module needs resetting.
Is this forund to the rear of the centre console under the rear ash tray i looked earlier and seen a small box there.
thanks

addo · Post by **addo** » 23 Mar 2010, 19:22

I don't know for sure. It will be a diecast box about five inches square, and held down with three or four screws. There is always a bold arrow pointing to the front of the car, on the box top.

carlberry64 · Post by **carlberry64** » 23 Mar 2010, 19:24

addo wrote:I don't know for sure. It will be a diecast box about five inches square, and held down with three or four screws. There is always a bold arrow pointing to the front of the car, on the box top.

is it a seperate box to the ecu or is it the main ecu also known as the airbag module

addo · Post by **addo** » 24 Mar 2010, 08:03

It's a specific airbag controller. Common brands marked on the top include Bosch, Autoliv, Breed. Look just forward of the gear lever in this photo for a visual cue:

Often there is a separate controller for lateral (side) airbags.

wheeler · Post by **wheeler** » 24 Mar 2010, 08:53

carlberry64 wrote:
addo wrote: Is this forund to the rear of the centre console under the rear ash tray i looked earlier and seen a small box there.
thanks

If its the same as the mk1 then the small box under the rear ashtray is the yaw sensor/giro for the ESP system. Does the car have ESP ?
The airbag ECU is roughly in the same position as the one in the picture in front of the handbrake & gearlever. Most of the airbag ECU's are now made of black plastic as opposed to the diecast metal.