Air Bag Deactivation

[ukchris]

First of all I think a disclaimer is required, what is presented here is just a summary of testing and results, if you decide to follow any of this then you do so entirely at your own risk, do not make any modifications to your car or its safety systems unless YOU are confident, I don't accept any responsibility if anything goes wrong.

So, on to the more interesting stuff. The passenger air bag deactivation bar has had me wondering for a while, it didn't seem it could be that complex. It's a teo pin connector so at first I though it would be just a switch that could easily be replicated, at a recent tech session we found out otherwise. Someone had the bar installed and we confirmed that until it was activated in the computer the air bag light was on, the key here is that the car *knew* it was connected so it must be more than a simple switch.

After a little digging (and a little help!) the wiring diagrams revealed what was inside, the wiring inside the buckle is as follows:

So basically the circuit is duplicated (redundancy?) and consists of a coupld of resistors, the switch bypasses the big resistor enabling the car to identify the switch is present as well as if it is activated or not.

With a little refresher course on Ohms law the circuit can be replicated with a few dollars at Radio Shack as follows:

So, solder all this together in a project box, clip the wires in under the seat and it will disable the passenger air bag in the same way as the deactivation bar / buckle! Here is my prototype for testing:

Now... a few people I have discussed this with raised very valid safety concernes about if it is worth risking an alternative, these are very valid issues that I wouldn't dismiss but I would mention the following points:

1. The car does a self test to identify the switch is in place and operational, if it fails in any way the air bag light will illuminate.

2. When activated the car indicated that the air bags have been disabled by flashing the air bag light for sixty seconds when you turn the ignition on.

3. Although I have tested the circuit as shown above I'm contemplating making it the same as the buckle with a DPST switch as I suppose it gives greater redundancy.

This is just a prototype, I'm trying to get a matching connector so it would slip in the same way (the clips just aren't going to do it for me!).

Again, I stress, this was an experiment, it in no way recommends you do the same or gives any guarantees. If you choose to follow what is outlined here you do so entirely at your own risk.

[ukchris]

It should be noted that to use this for air bag deactivation (with a child seat) the feature must be enabled in the car computer using a PST2 dealer computer. Without doing so the switch will generate an error and the air bag light will be illuminated.

You cannot do this "hack" without having the dealer activate it (or someone else with a PST2).

If you already have the airbag bar installed and are switching to a different seat (without the buckle) you should be able to replace the bar with a switch without any computer changes. As above, all disclaimers apply.

Chris.

[FerDeLance]

It should be noted that to use this for air bag deactivation (with a child seat) the feature must be enabled in the car computer using a PST2 dealer computer. Without doing so the switch will generate an error and the air bag light will be illuminated.

what should one expect to pay for such as service - from OPC or a specialist? thanks

[ukchris]

It should be noted that to use this for air bag deactivation (with a child seat) the feature must be enabled in the car computer using a PST2 dealer computer. Without doing so the switch will generate an error and the air bag light will be illuminated.

what should one expect to pay for such as service - from OPC or a specialist? thanks

It really depends on your dealer, although a quick update with the computer usually takes only a couple of minutes many dealers like to charge you for an hour so it can get costly. If you're installing the actual Porsche bar I think therer is a policy (in some places at least) that they will activate it for free but they may insist you buy the hardware from them. At the end of the day you'll have to ask, you might be lucky and find a local member that has access to the appropriate hardware too.

Are you installing the Porsche bar ir planning on making your own?

Chris.

[FerDeLance]

It should be noted that to use this for air bag deactivation (with a child seat) the feature must be enabled in the car computer using a PST2 dealer computer. Without doing so the switch will generate an error and the air bag light will be illuminated.

what should one expect to pay for such as service - from OPC or a specialist? thanks

It really depends on your dealer, although a quick update with the computer usually takes only a couple of minutes many dealers like to charge you for an hour so it can get costly. If you're installing the actual Porsche bar I think therer is a policy (in some places at least) that they will activate it for free but they may insist you buy the hardware from them. At the end of the day you'll have to ask, you might be lucky and find a local member that has access to the appropriate hardware too.

Are you installing the Porsche bar ir planning on making your own?

Chris.

Thanks for the quick reply. I'm going with the Porsche bar, I thought of a hack myself first but decided it was not worth the hassle and risking the life of my boy was not worth trying a DIY mod with.

I got a nearly new deactivation bar off ebay for 1/2 the RRP, but I guess I'll lose that saving now with the 2 minute computer update :(

[ukchris]

Thanks for the quick reply. I'm going with the Porsche bar, I thought of a hack myself first but decided it was not worth the hassle and risking the life of my boy was not worth trying a DIY mod with.

I got a nearly new deactivation bar off ebay for 1/2 the RRP, but I guess I'll lose that saving now with the 2 minute computer update :(

Call a few dealers, tell them you bought the bar and you understand that because it is a safety item that installation is supposed to be free. If it is indeed free I would think it's an arrangement with Porsche where they pay the dealer so they should be happy to help, if not ask for a price. If it seems ridiculous then look for an independant mechanic or another member with a PST2.

[Richard Hamilton]

I can help with the activation for you, and I'm not a million miles away from London. Drop me an email or PM if I can help.

[mb5885]

Hi,

Just purchased the de-activation bar new kit from Suncoast $150, and manufactured a male buckle to activate switch. Planned to install myself. Is there anywhere or anyone in the LA area that can help me out with the PST2 re-program? Thanks!

[cprenner]

Hi,

Just purchased the de-activation bar new kit from Suncoast $150, and manufactured a male buckle to activate switch. Planned to install myself. Is there anywhere or anyone in the LA area that can help me out with the PST2 re-program? Thanks!

"Manufactured a male buckle to activate switch?" Interesting... More info please!

[silverdude2]

First time responding - here goes

The switch or control you install should stay connected/switched in the event of a crash. You do not want the airbag to become enabled, so make sure you switch has a latch, and your connector is clipped or attached securely. My dealer wants 1 hour to install the bar and deactivate - seems like a ripoff. Anyone near Santa Barbara with a computer?

[jon cave]

On 6/10/2006 at 10:42 PM, ukchris said:

First of all I think a disclaimer is required, what is presented here is just a summary of testing and results, if you decide to follow any of this then you do so entirely at your own risk, do not make any modifications to your car or its safety systems unless YOU are confident, I don't accept any responsibility if anything goes wrong.

So, on to the more interesting stuff. The passenger air bag deactivation bar has had me wondering for a while, it didn't seem it could be that complex. It's a teo pin connector so at first I though it would be just a switch that could easily be replicated, at a recent tech session we found out otherwise. Someone had the bar installed and we confirmed that until it was activated in the computer the air bag light was on, the key here is that the car *knew* it was connected so it must be more than a simple switch.

After a little digging (and a little help!) the wiring diagrams revealed what was inside, the wiring inside the buckle is as follows:

http://i5.tinypic.com/140vg4w.jpg

So basically the circuit is duplicated (redundancy?) and consists of a coupld of resistors, the switch bypasses the big resistor enabling the car to identify the switch is present as well as if it is activated or not.

With a little refresher course on Ohms law the circuit can be replicated with a few dollars at Radio Shack as follows:

http://i6.tinypic.com/140viw0.jpg

So, solder all this together in a project box, clip the wires in under the seat and it will disable the passenger air bag in the same way as the deactivation bar / buckle! Here is my prototype for testing:

http://i6.tinypic.com/140kevp.jpg

Now... a few people I have discussed this with raised very valid safety concernes about if it is worth risking an alternative, these are very valid issues that I wouldn't dismiss but I would mention the following points:

1. The car does a self test to identify the switch is in place and operational, if it fails in any way the air bag light will illuminate.

2. When activated the car indicated that the air bags have been disabled by flashing the air bag light for sixty seconds when you turn the ignition on.

3. Although I have tested the circuit as shown above I'm contemplating making it the same as the buckle with a DPST switch as I suppose it gives greater redundancy.

This is just a prototype, I'm trying to get a matching connector so it would slip in the same way (the clips just aren't going to do it for me!).

Again, I stress, this was an experiment, it in no way recommends you do the same or gives any guarantees. If you choose to follow what is outlined here you do so entirely at your own risk.

Hello! The price of the oem seatbelt bars has gone through the roof since this post and this is the only DIY article I can find online but the pictures are no longer visible. Can someone please help me out with sending these pics again or a link to a newer article or something? Thanks!