Seatbelt Warning

My car freaked me out on Friday and I'm hoping you guys can guide me on how to stop it.

I arrived back at the airport after a weeklong trip to the west coast - threw my backpack onto the passenger seat and started driving home. After around 10 mins I got a seatbelt warning chime and light - I checked I was actually buckled in (I was) and after 20 seconds or so the chime stopped.... I assumed that a sensor was about to fail and was quietly annoyed. 5 mins later it went off again. This time I noticed it was the passenger seat that was alarming. It had mistaken the weight of my backpack as a passenger and was getting annoyed that it wasn't buckled in.

Is there anything I can do to turn this annoying warning off, or am I prohibited by my own car from putting anything of decent weight into the passenger seat?

I had the same thing happen when I sat my bag on the passenger seat. I could not find any solution in the owner's manual. I now put my bag in the back seat, I guess we could buckle the bag in the front seat?
Anybody else with a better solution?

Sorry to say this but there is now way to turn that system off for the passive safety. There is a seat mat sensor in the passenger seat called a OC3 seat mat. Basically what this sensor does it detect a person in the seat and then classifies them by weight and thus would adjust how hard the airbag would be deployed in a accident. Of course this sensor also turns on the warning light telling you to buckle the passenger seat belt.

Hmm. That's a pain.
I hate to turn off the airbag, as I do carry passengers, but it seems a little silly that my backpack with 4 days of clothes in it would set off a fasten seatbelt alarm. I was hoping I could just disable the warning.

Only way to turn that chime is off is if you ever get the car coded. A few of my clients get their car coded for that. Obviously getting the car coded is not a dealer service and you do it at your own discretion.