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!