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Replacing ignition switch with push button

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I have a 2005 Cayenne Turbo with Entry & Drive.

Instead of leaving the dummy key in the ignition, it seems that conceptually it wouldn't be too hard to replace the dummy key with a push button. Does anyone have the pinout of the ignition switch module? 

It seems likely, however, that there is some intense communication happening between the ignition switch module and the computer, so it is probably tougher than I'm thinking.

Has anyone attempted this before? 

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the dummy key contains a RFID "pill" which allows the immobilizer to code the DME to allow the car to start.  If you jury rigged a push button, you would still have to insert the key before the car would actually start.

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So does the dummy key need to be programmed to my ignition? I have the dummy key on order, and I assumed that it was just plastic, and that it would work if I had the key fob in my pocket.

So I'd need to have the ignition switch with the dummy key back inside the dashboard if I wanted to have a push button start where the key currently is?

Do you know the pinout of the ignition switch? it sounds like I'd probably have to tear the switch apart in order to get a push button working.

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The, dummy or real, must carry the RFID pill with a code to match your immobilizer or the system will not work.  The RFID pill must be within a certain distance of the key slot for it to be recognized or nothing would happen. If you mounted the key in the switch and put it behind the dash, anyone that got into the car could start it and drive off as you have neutralized the security system.

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I guess I'm misunderstanding the dummy key and entry & drive system. I thought that it is intended to leave the dummy key in the ignition all the time, and that it wouldn't actually start the car unless I have the genuine, only-for-my-car keyfob near the ignition switch (like in my pocket). 

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The fob turns the alarm system off and gets you into the car, but a real or dummy key must be in the ignition for the system to work. 


I have done some additional research, and the car is reading the RFID from your fob, or from the real key (they both have it).  The dummy does not have the pill, which is why it sells so cheaply (around $20 at retail), but requires the fob be nearby.  So to add a push button start/stop, you need the button and some additional electronics to control both the "start" and the "stop" functions, which are normally controlled by the DME and security system via the key.  On a car without PED, the key functions are simple make/break circuit systems, with the PED it is a bit more complicated as both the DME and immobilizer/security networks are involved.

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  • 3 weeks later...

As far as I know the Dummy key is nothing more then a piece of plastic!

I just bought my Cayenne Turbo and the Dummy Key wasn't with the car,

so I ordered a new key from the dealer without any vin!

When I received the Dummy key and put it in the ignition it started right up with the key in my pocket,

so the dummy key isn't coded it is just a plastic key to start the car when the normal key is present and detected.

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