Toyota SIENNA 2011 Quick Reference Manual page 172

Seat belt pretensioners (front seats)
Pre-collision seat belts (front seats of vehicles with pre-collision
system)
If the pre-collision sensor detects that a collision is unavoidable, the
pre-collision system will retract the seat belt, thus enhancing the
effectiveness of the seat belt pretensioner in a crash.
The same will happen if the driver makes an emergency braking or loses
control of the vehicle. (→P. 307)
1-3. Adjustable components (seats, mirrors, steering wheel)
I n f o r ma t i o n P r o v i d e d b y :
The pretensioner helps the seat
belt to quickly restrain the occu-
pant by retracting the seat belt
when the vehicle is subjected to
certain types of severe frontal
collision.
The pretensioner may not acti-
vate in the event of a minor frontal
impact, a side impact or a rear
impact.
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