2010 Toyota Yaris Owners Manual - Page 92

1-3. Adjustable components (seats, mirrors, steering wheel) Seat belt pretensioners (front seats) The pretensioner helps the seat belt to quickly restrain the occupant by retracting the seat belt when the vehicle is subjected to certain types of severe frontal collision. The pretensioner may not activate in the event of a minor frontal impact, a side impact or a rear impact.