i did a google search. it seems that the number of times you switch the key on/off varies by model. one comment thing mentioned is that the chime gives one ding when disabled. as yours doesn't STOP dinging you might have to try switching 3, 4, or 5 times to see if it works.
it's worth a try right?
2004 Dodge Ram 3500 Seat Belt Dinger Will not Shut off.? - Yahoo! Answers
(you'll have to cut & paste the full link together)
these two posts came from a cached copy of a dead link.
I have done this on many vehicles for customers. Sometimes it takes a few
times. I did a Durango and I had to unbuckle and buckle the seatbelt 5
times. I did it on a Ram reg cab and it would only disable it if I did it
3 times. The first mistake I made the first time was I started the
engine. Just turn the ignition on don't start it.
1. Buckle your seatbelt without the key in.
2. Insert key and turn. DO NOT START ENGINE!!!!!
3. Wait until the seatbelt light turns off.
4. Unbuckle and buckle the seatbelt 3 times.
5 Leave seatbelt buckled.
6. Turn Key to off position and you should hear a chime. If not start
over. Try buckling the seatbelt more than 3 times.
Okay- determined to figure out this damn belt reminder, I tried several
different things and finally succeeded using a different technique:
1. Turn the key to on without starting the engine, but do NOT buckle the
2. Leaving the key on, buckle and unbuckle the belt several times.
3. On the third buckle, mine chimed once.
4. Voila!! Now when starting, the belt chime sounds briefly. After
driving with the belt on, unbuckling the belt activates the instrument
panel light, but NO MORE ANNOYING CHIME!
5. Celebrate with icy cold adult beverage.