This is from an old post, but a great possible "how to".
I shut off the annoying Seat belt minder in under 60 seconds.

1. Ensure the front passenger seat is unoccupied.

NOTE: the next steps (2 to 5) must be completed within 60 seconds.

2. Turn the ignition to the RUN position (do not start the engine).

3. Engage the driver safety belt buckle and wait until the seat belt warning lamp extinguishes.

4. Unbuckle the driver safety belt buckle and wait until the seat belt warning lamp illuminates.

5. Repeat Steps 3 and 4 a further eight times.

6. When the driver safety belt buckle is unbuckled for the ninth time a single chime will be heard. The single chime is confirmation that the Beltminder feature has been disabled.

The Beltminder feature will remain disabled even after leaving the car until the above process (Steps 1 to 6) is repeated.

If you repeat the process the Beltminder feature will be reactivated.

Done this on mine drove me mad

Hi all
Is the seatbelt minder in question the chime that sounds when the passenger seat is occupied but the belt isn't fastened? My 2004 XJ6 has this feature but not on the drivers seat....as far as I know. Maybe it has been disabled.
Pete

Just to prove a point I unfastened my seatbelt today while driving along and there it was! The chiming sound.
Oh well you learn something every day.

Luckily I wasn't spotted by the local constabulary, they would never have believed the excuse