fammdw

Here is how you disable the seat belt chime in your 2007 - 2008 Explorer:

-Turn car keys to power up but not start the car.
-Wait till the seatbelt light goes out (takes up to 20 seconds)
-Buckle and unbuckle the seat belt 3 times
-Turn your park lights on then off once
-Buckle and unbuckle the belt 7-12 times till the seatbelt light comes on with a solid glow. Keep the seatbelt buckled this time until the light goes out.
-Unbuckle the seat belt - Seat Belt light flashes rapidly
-Once the seatbelt light stops flashing, buckle the seatbelt - Leave it buckled
-Start up your vehicle
-Seat Belt light will flash rapidly again indicating the disable was successful.

This disables the programing on the computer on board. To turn it back on to chime. Repeat these steps.

Note - I only know for sure that this works on a 2007 Explorer.