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Old 03-02-2017, 07:31 AM   #1
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Join Date: Apr 2009
Location: MD
Posts: 268
Hacking the Child Seat Air bag Deactivation system

Without the Por$che Child Seat and deactivation bar. Hacking is probably the wrong term, as I didn't bypass the system; I emulated it at a fraction of the cost.

In my 2003 Boxster S the only way to safely use a child seat is to disable the passenger air bag, and the entire hardware for this is not readily available. The system has two parts: A bar that bolts to the seat rails and a Porsche seat with a custom buckle to plug into the bar. The bar is still available (at about $230) but the seat is long out of production (and was about $600 when it was new). Without the custom buckle there is no way to easily activate the system. So your only option is a garage sale find of an old seat, which if only for appearance reasons will likely have seen better days.

Have a two year old grandson who I needed to occasionally (more like rarely) pick up from daycare and wanted to also be able to take for a spin with the top down. Definitely not worth the cost of the official Porsche child seat and deactivation bar, even if the entire assembly was still available. Not liking this option or price, I decided to build the circuitry to emulate the insertion of the buckle into the bar. It's so easy that even this guy could do it.

I found online a diagram of the circuitry that's housed in the buckle-receptacle portion of the deactivation bar and copied it. It's only 4 resistors and a double-pole double-throw switch. If you use a solderless breadboard (normally used just for prototyping - Amazon sells them) to build it, it's an easy project, once you figure out how to read the logic of the circuit (which was new to me). Mounted it all in a project box (which could have been a lot smaller, but hey, it works) and it's behind the passenger seat so nobody sees it. The beauty of a breadboard is that you can try different layouts for the board until you get it right. The connector for this is under the front of the passenger seat, and I couldn't find a factory connector to fit so I just cut off the connector and used insulated spade lugs.

You're know it's working right (and the car is programmed correctly) if when you flip the switch the airbag light flashes for 60 seconds at startup (10 seconds for cars built pre April1, 1999) and the light is off (normal) when the switch is in the off position.

If you want to check your work before plugging it in ( which I highly recommend) the resistance should be 2.25k ohms with the switch open and 255 with it closed. My resistors were a little off (take it up with my quality control department that accepted resistors that were slightly out of spec) but it still worked perfectly. And even though I'm an economist and not a hardware guy, this was an easy project. Of course, I refuse to accept any liability for your actions.

See pics and circuit diagram at

Boxster 986 Passenger Airbag deactivation switch - Album on Imgur

I initially mounted the switch on a wire that I intended to thread towards the front of the passenger seat, but I realized that it was easier in many ways to just mount the switch to the box, so I redid it slightly (the blue wire in the picture that had the switch on the end is gone).

My indie shop did me a favor and coded the car's computer (I doubt if a dealer would have activated it). It cannot be activated with a durametric, but they had one of the older Porsche tools.

As soon as we get another nice day that little boy is going for a top down cruise.


Last edited by Cbonilla; 03-13-2017 at 08:02 AM.
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