Seat belt and parking brake warning enable

The previous owner had the seat belt and parking brake audio annunciator (buzzer) disabled. It works for other things, so I'm guessing it was disabled in the systems computer. The warning lights in the instrument cluster work. I've heard of the dealer disabling it for people in later generation Tundras, but I can't find anything on how it's done in 2006. Can you tell me how I can enable these warnings?

 

https://itstillruns.com/disable-seatbelt-alarm-toyota-5552324.html
Maybe this will help?

 

Thank you for your quick response.
I don't think this is correct. Pressing and holding the trip odometer button like that is how one resets the maintenance interval warning light. I.E. time to change the oil. One hols it in until the dashes in the odometer display count down to zero and it's reset. BUt I tried it anyway because i just changed the oil and don't mind. It did not work. First off it mentions "between your trip odometer and your odometer reading. Well mine is integrated into one readout. Pressing the button changes between ODO, Trip 1, and Trip 2. Pressing and holding resets the displayed trip. It also mentions that "B off", or maybe "B on" in my case, would be displayed in the information center display. I have no information center.
Thank you for the suggestions, do you have any other ideas?