Locked my XJR and my nearby XK8 gave a warning beep. Fob for each does not work on the other car. Figured out boot of XK8 was not fully shut. Posting just because interesting.

 

Scratch what I wrote. The XK8 fob works only on the XK8. The XJR works fully on both. Someone explain that.

 

the solar wind

 

I find that very surprising but I'm guessing that the codes required by the two cars are very similar but one car has a slightly improved design and has a more tightly restricted spec.

Richard

 

Did you ever add fobs to either car? At some point one of the XJR fobs was added to the XK8 (or you mixed the fobs up and added the XK8 fob to the XJR). The fobs don't know what car they are programmed to, only the car knows.

 

Surely you can only program a fob to one car? The XJR fob fully works on both cars.

Richard

 

Bear in mind you are programming the car to recognise the fob, not the fob to recognise the car when you add one. The cars can't communicate with each other or send a signal back to the fob. Programming the fob to another car doesn't delete the code from the first car.

It's exactly the same as if you got a matching lock for the key - the first lock wouldn't somehow stop working.

 

I once owned a 1998 Ford SHO, clicked the key fob and a Ford Truck in the area unlocked along with my car. Hit the lock function and both vehicles locked.
wj

 

Make sense.
Hear is the entire story.
Sort of lost one of my XJR keys and only XJR fob. I say sort of because I drove the car home one night and couldn't find the key and fob the next morning. I suspect my golden retriever or a grandchild. I refuse to blame my memory.
Had a spare XJR key and a spare fob that I think came from the XK8. As @dibbit says I programmed the XJR to the XK8 fob. So we now have one fob (the long time XK8 fob) that just works on the XK8 and one that works on both. I think I remember the cars can remember 5 fobs. I guess what to do is go through the program procedure on the XK8 5 times with its original fob to clear out the fob linked to the XJR.

 

You should look up:
The Effect of Gamma Rays on Man-in-the-Moon Marigolds.
I think they have something on this.