I just discovered this problem in my 91 EF Si and it is BUGGING THE **** out of me! When I have a passenger in the car and they get out when the car is on and close the door, this annoying *** little beep starts and WONT STOP! Its the beep the car makes when you dont put your seatbelt on when you start it up. I have made sure all the doors are closed, I have messed with the seat belt buckles - nothing stops this beep unless I turn off the car and start it again. What might cause this and how can I stop it? I am going INSANE. Thanks...

 

disconnect the plug under the passenger seat, that should stop it!