I too have to place my briefcase on the passenger seat for easy access. This "weight" (just a normal case) sets off the seat belt alarm which is annoying for a good 30 seconds. I do attach the seat belt to avoid this but still this seat sensor is TOO sensitive! There is also a problem when getting out of the car - I cannot lock the doors without unlatching said passenger seat belt or I get a major alarm going off. It is inconvenient to say the least and for the price of the vehicle I would expect some way to fix this. Anyone know of anything? I tried ALL the methods suggested for other Toyota vehicles - pressing and holding the ODO button, fastening and unfastening the seat belt, etc. TO no avail. In fact NO "b-on" or "b-off" symbol appeared.

That all said I love my vehicle. I have converted the back to a work area for surveying equipment - all seats down. Am getting 27- 29 mpg on mostly highway driving. Fun!