Fix for Airbag light (airbag bypass)

[BlueZHP]

I recently purchased a used 04 ZHP sedan with 115,000 miles on it. The owner told me that it had an intermittent airbag light that would come on after someone sat in the pass. seat and the light would clear randomly. I got him to take $200 off the asking price. The previous owners records showed that the passenger seat occupancy mat was replaced at 49,000 miles.

I didn't want to take the whole seat apart so I installed a Passenger seat occupancy mat bypass module.
http://i711.photobucket.com/albums/ww115/briandude25/airbag.jpg

Installation consisted of cutting the pass airbag mat wires loose and splicing the bypass module. After this was done the airbag light has not come back on. My airbag light was off when I installed the bypass. The airbagRX website states you may have to have a dealer clear the airbag light.

I purchased the bypass at http://www.airbagrx.com/

I hope this helps anyone with this problem.

[09mageec]

I have this same problem and its very annoying. Anyone who sits in the passenger seat always thinks something is wrong with their airbag haha. Anyway thanks for the advice!!

[gr330zhp]

Sooo now the airbag really doesnt work??

[Crickett]

I've considered doing this too, but have yet to find a definitive answer on whether the airbag will always deploy or not. I think the bypass module's electronics emulate the resistance of a passenger so the airbag will always be deployed; does anyone know for certain?

[kayger12]

Sooo now the airbag really doesnt work??

No- bypass tricks the computer into thinking someone is sitting there, so it fires no matter what.

Looks like a pretty good option for someone who doesn't feel like tearing the seat apart.

Bookmarked the website for the future.

Nice find, Blue- thanks for posting.

Droid X. Tapatalk. Use it.

[kayger12]

I've considered doing this too, but have yet to find a definitive answer on whether the airbag will always deploy or not. I think the bypass module's electronics emulate the resistance of a passenger so the airbag will always be deployed; does anyone know for certain?

Correct. According to their website the bag will always fire regardless of occupancy.

Droid X. Tapatalk. Use it.

[Crickett]

Correct. According to their website the bag will always fire regardless of occupancy.
Perfect! Now to dig up the DIY to put together the correct resistors & other bits. (I always love soldering my own electronics. :biggrin)

[danewilson77]

The "con" to this is that in any accident you have....BOTH airbags will go off.......vice just the one side. Your car always thinks someone is sitting over there in the passenger seat. The occupancy sensor is there to save a $3k airbag, should no one be sitting there, when you get into an accident.

I recommend fix the problem correctly...in the long term.

[gr330zhp]

Ahhhhh I see. BMW had replaced my mat at 30k i believe, luckily it was under factory warranty. Hopefully wont nned another

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[johnrando]

A little off topic, but do our passenger airbags have the weight sensors that manage deployment if a kid is in the passenger seat?

[09mageec]

The "con" to this is that in any accident you have....BOTH airbags will go off.......vice just the one side. Your car always thinks someone is sitting over there in the passenger seat. The occupancy sensor is there to save a $3k airbag, should no one be sitting there, when you get into an accident.

I recommend fix the problem correctly...in the long term.

Agreed lol, I want the absolute least of amount my beautiful Alcantara interior ripping haha

[danewilson77]

Yes....I believe they will only become active, above a certain weight.

[Marcus-SanDiego]

Agreed lol, I want the absolute least of amount my beautiful Alcantara interior ripping haha

Plus the cost ($$) of the airbag deploying.

[kayger12]

I'm going to go outside of the box here and say that I'd rather have both bags deploy.

If the car is going to take a shot solid enough to deploy the bags, it's going to be an insurance job and I'll be paying a $500 deductible whether it's one bag or both.

Taking it a step further, airbags are only supposed to be good for ten years, at which time you are supposed to have them replaced iirc. With that in mind, I'd rather have the bag deploy and have it replaced at the insurance co's expense...

...or am I being crazy here?

[Ryans323i]

The only con to that line of thought that I can think of, is an added $3k to the bill, could be just enough for the insurance to "total" the car.

[Marcus-SanDiego]

Kayger, you are crazy. But I agree with you on this one. I don't have a problem with this. You're right. If the airbag deploys, there is likely enough damage to make a claim on your insurance. So, why not?

[kayger12]

The only con to that line of thought that I can think of, is an added $3k to the bill, could be just enough for the insurance to "total" the car.

To be honest, Ryan-- if the car was that close dollar-wise to being totaled, I wouldn't want it repaired-- I'd rather they total it.

[kayger12]

Kayger, you are crazy.

Yeah, I'll give you that. :)

[Ryans323i]

$3k worth of body work is a lot. But I can't argue with your reasoning. If your car's totaled, you'd probably walk away with a $16-17 (maybe more) check and the possibility to replace what you've lost. If my car's totaled I get maybe a $6k check. With over $14k worth of mods, I'd be screwed. It's my own fault, I know. But it's a fear I think about every time I drive.

[danewilson77]

So I will play bad guy advocate here.

What is the speed/force necessry to deply airbag? Idk.

But let's say that speed/force is x. Let's say you hit object at speed/force x....and it deplots airbag....but only causes superficial damage to bumper and front end. The airbag deployment unecessarily could total car? Maybe?

It also kills me that we would be anal enough to get a cover for an oil drain pan....but not ensure our airbag system is properly functioning. Noy saying I'm not the same....just offering food for thought.

EDIT: oops...almost forgot. Keith...you crazy mon.

Droid! Srs Legitness!

[kayger12]

So I will play bad guy advocate here.

What is the speed/force necessry to deply airbag? Idk.

But let's say that speed/force is x. Let's say you hit object at speed/force x....and it deploys airbag....but only causes superficial damage to bumper and front end. The airbag deployment unecessarily could total car? Maybe?

It also kills me that we would be anal enough to get a cover for an oil drain pan....but not ensure our airbag system is properly functioning. Noy saying I'm not the same....just offering food for thought.

EDIT: oops...almost forgot. Keith...you crazy mon.

Droid! Srs Legitness!

Valid points, DW.

And it varies from manufacturer to manufacturer, but typical airbag deployment trigger is about 14 mph into a fixed object or 25 mph into a moveable object. That's with a square hit on the front end. Angle impacts require higher speeds.

[danewilson77]

Good data brutha. Thanks!

Droid! Srs Legitness!

[Crickett]

A little off topic, but do our passenger airbags have the weight sensors that manage deployment if a kid is in the passenger seat?
I do believe so, John. From what I remember when reading up on the electronics required to bypass the seat weight sensor, there were two different resistance values that would trigger different airbag firing speeds/force/whatever. One value would indicate a full-sized person in the seat & one to indicate a lighter passenger (e.g. a child).

Also, I'm with Keith on this one: if I'm in an accident that's severe enough to pop one bag, I'd prefer the second to go too. The potential added repair costs don't outweigh the alternatives if I'm carrying a passenger & that bag doesn't fire. It's just a safer failure mode.

[das boots]

Reviving a very old thread. And also, I like to keep this going until.......I'll make it as short as I can. I am having a hard time resetting my oil reset. Evidently, I have a busted reset knob. Vince scanned the car and found out that the driver's airbag has a fault. The airbag light on the cluster does not come on. The cluster was loose and can be wiggled. So deductions was somebody already had access to the cluster possibly removing the air bag lamp so the airbag lamp will not show. Possible driver side air bag malfunction or some wiring somewhere. I will end up openning up my cluster since I will have to replace the reset knob (after market already ordered). To see if the lamp was removed. If it is, do I reinstall the lamp or live it alone? Do I spend the $$$ to T/S the air bag problem? Is this a dealer fix or an indie (Shane) can have this done? Wondering aloud. Thanks.

[danewilson77]

The airbag problem can probably be easily fixed (Drivers side - whew!) by replacing the seat belt tension or seat belt switch on the drivers side. The code you got, should have pointed you in a direction here.

The lil LED in the cluster may only be "taped over" / "covered up". Lets hope so.

This way....you....fix your knob with the parts ordered.....and are able to troubleshoot and repair the drivers side airbag problem.

If he removed / disabled / damaged the LED for the SRS airbag warning....I would just buy a new cluster and return the knob parts (Or sell online). The mileage WILL resynch to your cars computer.

[das boots]

The airbag problem can probably be easily fixed (Drivers side - whew!) by replacing the seat belt tension or seat belt switch on the drivers side. The code you got, should have pointed you in a direction here.

The lil LED in the cluster may only be "taped over" / "covered up". Lets hope so.

This way....you....fix your knob with the parts ordered.....and are able to troubleshoot and repair the drivers side airbag problem.

If he removed / disabled / damaged the LED for the SRS airbag warning....I would just buy a new cluster and return the knob parts (Or sell online). The mileage WILL resynch to your cars computer.

Need a little kick in here. Why is it a easy fix on drivers than on passengers side? Where is the seat belt switch? Would replacing the seat belt tension meaning the whole seat belt from the B-Pillar? The code scan was not able to go forward from the diagnosis since the lamp was not lit on the cluster. It looks more like not tape over in front. Will see in the back when I open it up. How easy damaging or bad is removing the lamp or LED? Buying a new cluster would cost a pretty penny.

[danewilson77]

The passenger side has the evil "Passenger side occupancy sensor" that goes bad. You won't be replacing that, if that's the fault. You either live with the fault, bypass the switch, or buy a new seat. I still have the occupancy sensor hanging in my garage, from when I attempted diy.

I will fill ya in on more later...gotta run to job #2.

[das boots]

Will wait for your pointers. Thanks.

[danewilson77]

The passenger side has the evil "Passenger side occupancy sensor" that goes bad. You won't be replacing that, if that's the fault. You either live with the fault, bypass the switch, or buy a new seat. I still have the occupancy sensor hanging in my garage, from when I attempted diy.

I will fill ya in on more later...gotta run to job #2.

Yes...I am quoting myself. More info....

The common culprits are:
1) Seat belt pre-tensioner (a pyrotechnic device that tensions the seatbelt in the event of a collision);
2) Passenger seat occupancy pad (detects whether there's someone in the passenger seat, doesn't deploy passenger airbag if there's no passenger)
3) Door air bags (will light up the airbag light if they are disconnected while the car is electrically powered, such as durnig a window regulator repair - even though there's no problem with them)

If you're certain it's the seat belt pre-tensioner, check the below diagrams. I would provide the part numbers, but you'll need to know the manufacture date (not model year) to pick the right parts... manufacture date should be on the driver's door jamb sticker, I think.

For the most accurate diagrams and part numbers, click "select another car" on RealOEM, and put in the last 7 digits of your VIN.

http://www.realoem.com/bmw/partgrp.do?model=EV53&mospid=47725&hg=72

[das boots]

URL..no workie. And aside from this, anybody have the wiring diagram or a pic of the driver side airbag and the various connecting plugs to connect the air bag? Anybody done a write up on opening up the door cards and what looks like inside?

[danewilson77]

Mmm....it opened up for me when I posted. Now it doesn't. Will fix.

[danewilson77]

Here it is.

http://www.realoem.com/bmw/partgrp.do?model=EV53&mospid=47725&hg=72

HTC Thunderbolt+TT

[danewilson77]

URL..no workie. And aside from this, anybody have the wiring diagram or a pic of the driver side airbag and the various connecting plugs to connect the air bag? Anybody done a write up on opening up the door cards and what looks like inside?

Just disconnect battery and remove door panel using a window regulator DIY. Really. What car do you have? ///M3?

http://www.skene.org/bmw/window/index.html

HTC Thunderbolt+TT

[das boots]

Finally opened. Window Regulator DIY it is. Thanks.