Sorry, I had to dive off..
To answer your question about coding it....
The decoding is done in the module, not the reader ring. So if you have the matching key and module, simply changing the reader ring will not effect the operation.
I hope this helps....all you have to do now is find it.........lol
It shouldn't do but it does seem to you do apparently need the correct ring I've never done a test though.
The decoder ring, is in fact just an antenna. It comprises of 2 coils of copper wire wound tight and sealed in a plastic moulding.
One of the coils transmits a radio signal to the key when you turn the Ign on.
That small amount of RF energy is picked up by the "chip" in the key.
The "chip" is in fact an RFID device (radio frequency identification) which has another coil would round it.
This picks up the signal and converts it into a dc current which is stored for a few seconds by a capacitor.
The capacitor energises the "chip" to generate a coded signal which in turn is picked up by the second coil in the decoder ring and sent back to the control module where it is verified, and the immobiliser circuit is released.
You can find the same RFID technology on shop goods, in the tags they use to detect shoplifting. They come in all shapes and sizes.
The antennae are the big boxes either side of the shop doors.
Look inside a software packing box or something similar and you can see the RFID tag, its a flat foil printed circuit, normally on the back of the price ticket.
The spiral part is the antenna and if take a magnifying glass, and look in the middle, you can see the chip which contains the RFID device and capacitor.
