I'm sure that some of you are annoyed with the seatbelt BEEP. If so this is for you. 

This will work for all Scion / Toyota. 

It can be turned off. 
1.) Power on (ignition on will do) 
2.) Set trip/ODO to ODO (if its already on ODO you will have to cycle through) 
3.) Power off 
4.) Power on w/brake on 
5.) (Within 6 seconds), press and hold the ODO for 10 seconds or more 
6.) While STILL holding the ODO *after 10 seconds*, buckle BOTH seatbelts. Now release the ODO 
7.) You will see in the trip display either a "b on" or "b off" 
8.) Press the ODO to toggle between "b on" or b off" YOU WANT "b off" 
9.) Now power off. 

If battery is disconnected, you may lose your setting. Default is always "b on"