Airbag Light - finally off!

M

Marco

Member
 Hampshire
After a long time and many attempts with generic readers I have eventually managed to clear the Airbag light. I used the INPA software and cable from bmcables.com

Was a bit tricky at first as if you go into the Airbag Module it says it cannot connect (and so I thought the Airbag ECU had gone), but apparently not all the models have them, mine (2003 2.5) doesn't have the Airbag Module, it uses satellites (allegedly). You need to connect to "Safety Modules" as per this post here:

http://www.z4-forum.com/forum/viewtopic.php?f=2&t=48452
{Thank you "powerontap"}

Turns out it was the "seatbelt tensioner left" which I believe is one of the most common causes of the Airbag Light going on (along with the Occupancy Sensor Mat).

The reason I am posting this is I know many people are affected by the Airbag light problem and so I'm hoping this may help someone else. Also, if anybody is in the area (Farnborough) and would like me to assist with their light, I am more than happy to help.....
 
Is it the light with a airbag looking object infront of a person sitting in the seat? Because I noticed mine randomly came on yesterday i hope I don't crash and my airbag doesn't go off! :cry: :!:
 
Haha, yes sounds like that's the one! There are a lot of theories around about whether the (working) airbags would deploy in the event of an accident, and many people seem to think that if there is a fault, BMW disengages the entire airbag sytem. I personally don't know if that's true or not, I find it hard to believe that BMW would turn off all airbags and potentially make it unsafe for a driver in light of one fault with one of the airbags or associated components. My assumption is that whatever is working, will still deploy as per normal procedure..........but I guess you'll only find out if you need them (which I hope you never do)! :driving:
 
Glad you got it sorted and found the correct gear to do it. Airbags used to be a real issue to reset outside of main agent.

In terms of not deploying. Certainly BMW service advise they won't deploy if any error is showing. Personally I tend to favour it being correct in them not deploying. The risk of deploying incorrectly and liability for subsequent injury, seems greater to me than saying 'it doesn't deploy so don't drive it, until fixed'.

I would love a definitive answer though.
 
This is right from a BMW tech document, though never seen/heard about knee airbags but they seem to be a US model thing.

So don't worry, BMW try keep you safe irrespective of the faults! They are just there to warn you that they might not operate properly which is always a good thing to know!

The only caveat is if the fault is in the passenger airbag switch if you have one, so if you have an airbag light on AND a passenger switch, get it checked because if it's a switch fault it will assume that a child seat is fitted and NOT trigger!

Airbag Triggering

Numerous crash and road tests under extreme conditions have been used to set the BMW
triggering thresholds for all possible types of accidents.

The triggering thresholds are primarily divided into 4 groups according to crash severity:
• CS 0: no crash (parking damage) CS=Crash Severity
• CS 1: light crash
• CS 2: crash of medium severity
• CS 3: severe crash

The triggering thresholds have been set depending on the crash severity and including
other factors such as direction, overlap on collision, and depending on the evaluation as to
whether the occupant was wearing a seatbelt or not.

This results in the various trigger thresholds for the activation of the various restraint systems.

Triggering in the event of errors.

If a fault is detected in the seatbelt buckle detection system, it is assumed that the seatbelt
is not fastened. The triggering threshold is lowered. In spite of the fault recognition, an
attempt is made to activate the seatbelt lock tensioner.

If a fault is detected in the seat occupation detection system, it is assumed that the seat is
occupied. The restraint systems are activated.

If a fault is detected in the airbag switch, it is assumed that a child's seat is fitted. The front
airbag and side airbag on the passenger side are not triggered.

Triggering in the event of a crash

The following examples illustrate the actuators that can be activated:
• Front-end crash
• Side-on collision
• Rear crash

Front-end crash

In the event of a front-end crash, a distinction is made between crash severity "light to
medium collision" or "severe collision" (CS 3).

In the case of crash severity from light to medium collision (CS 1/CS 2), the driver's/front
passenger's airbag are not triggered if it is detected that the occupants are wearing seatbelts.

If the occupants are not wearing seatbelts, the driver's and front passenger's airbag would
be triggered.

The seatbelt tensioners are triggered in all cases.

As of crash severity CS 2, the driver's/front passenger's airbag as well as the seatbelt tensioners
are triggered. The safety battery terminal is activated, the electric fuel pump is
switched off, and an emergency call is placed if a correspondingly prepared telephone is
present in the vehicle.
In the US version, the knee airbags are also triggered.

Side-on collision

In the event of a side-on collision, a crash severity distinction is made between medium and
severe collisions.

As of crash severity of CS 2 (medium collision), the side airbag is triggered on the impact
side. In the event of crash severity CS 3 (severe collision), the safety battery terminal is also
activated, the electric fuel pump is switched off, and an emergency call is placed if a correspondingly
prepared telephone is present in the vehicle.

Rear crash

As of crash severity CS 2 (medium collision), the seatbelt tensioners are triggered.
In the event of crash severity CS 3 (severe collision), the safety battery terminal is also triggered,
the electric fuel pump is switched off, and an emergency call is placed if a correspondingly
prepared telephone is present in the vehicle.

Knee Airbag

In the event of a crash of sufficient severity, the gas generator is ignited. The escaping gas
fills the airbag, which tears open the cover of the knee airbag so that the airbag can
emerge.

The airbag spreads out beneath the steering column and/or in front of the glove compartment
and cushions the lower thighs of the occupant.

The support of the lower thighs initiates a controlled forward shift of the upper body, which
is cushioned by the driver or passenger airbag.

The knee airbags can only be seen by the lettering "AIRBAG" on the cover of the airbag
module as well as on the cable connection for the airbag module.
Click to expand...
 
My 2004 Z4 failed its MOT today solely on the Airbag light being on. BMW have passed it the last 2 years but it apparently became law in March that no airbag lights can be on. BMW did check the problem and told me it was the passenger seat sensor and in the event of a crash the airbag would now automatically deploy even if the seat were vacant. On that basis I decided to not do the £400 quoted fix. However, now I have 10 days to get it done..!! If you're in Farnborough Kent I'll take you up on the offer to help people..
 
You can buy a box that sits under the seat, and has a plug that goes into the multi-plug under the seat rather than the occupancy sensor and seatbelt clasp switch.

That basically says the seat is always occupied and the seatbelt is clasped.

So now you have a car that will do what it would have done any way in the event of a crash, but the light isn't on to satisfy another 'rule' that will do nothing except increase the incidence of 'box' sales on eBay that make lights go off.

Thus probably leaving more used car buyers worrying if there are real important faults hidden that they don't know to track down which a light would have told them about.


The rule is just silly and will probably serve to do the exact opposite of what it's intended to do, and that is make SRS devices in most cars generally be left un-repaired where a serious fault exists.




I just blocked my light for my MOT this year. My car will do everything I need it to do in a crash, in my case the light is simply telling me the occupancy sensor expected doesn't match the one actually fitted... but the system works in every single functional way in INPA.

Go figure eh. You've got to go make your car more broken to fit 'rules'

Dave
 
Hi, don’t want to open a new thread, but does anybody know how I can reach the power supply of the passenger airbag in an e85?
Thanks
 
98D5. I have check the seatbelt and seat wiring and are fine. I suspect the power supply to the airbag may have an issue, so I would appreciate advice how to reach it.
 
That code can also point to a fault on the yellow plug to the left of the battery. Have you tried cleaning that? Possibly has too high a resistance.
If it is a prefacelift it can also point to a failure within the SBSL. Facelifts have a different system which is why I keep asking
 
Hi, thank you for your reply. With the help of the various threads here I have checked these and look fine. It is a 2006 facelift. Cheers
 
Well the usually infallible database of fault codes has let me down then, as it only shows that code for the pre-facelift.

When you read the code, what actual wording did you get with it?
1771773595670.png
 
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Another thing to look at: check inside the loom connector at the door pillar for corrosion.

Btw, looking back I can see you were investigating fitting a passenger airbag switch. Has this fault only appeared since you did that?
 
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