So, there's been a lot of talk about getting new keys, programming keys, etc. But I have a slightly different question: what exactly is in the key fob and is it really needed?

To be a little more specific I have to explain that I have a partial key fob that I was given by the dealer when I bought my X-Type (they did make me pay for it and I think it was ~$50.00). It consists of the "switch blade" key but not the buttons or battery. I asked for it because I ride a motorcycle and keep my riding gear in the trunk and have to get it out before riding away. I've always done that and I have had a spare key for my car on my motorcycle keyring. That wasn't a problem when I drove a car with old fashioned "blade" keys, but with the Jaguar I didn't want to have a heavy set of keys on my motorcycle keyring. A (partial...) solution was the partial Jaguar key.

The key unlocks the doors but won't start the car. That's ok because all I need it to do is give me access to the trunk. I never use it to operate the car.

That said, does anybody know if I could program the key (via the approach presented in the Replacing key - X Type 2004 or would the lack of some electronics in missing part of the key fob interfere with the key operating the car.

I suppose I could simply try the key programing approach but I'm concerned that the car may decide that something bad is happening and totally lock me out by preventing even my regular keys from working.

Anybody have any ideas?
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Jaguar: Grace, Pace, and Space - Sir William Lyons

 

As I understand it the part of the fob with the keyblade has the electronics for the immobiliser. The part with the buttons on it has the electronics for remote access.
As I mentioned in an earlier thread, on the UK X Types if you have 2 keys that will start the car then you can program a 3rd yourself. Don't know about US versions.
The method is in the earlier thread.