Toyota Prius 2011 Manual page 86

1-4. Adjustable components (seats, mirrors, steering wheel)
Adjusting the seat belt shoulder anchor height (front seats)
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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. 257)
86
Push the seat belt shoulder
anchor down while pressing
the release button.
Push the seat belt shoulder
anchor up.
Move the height adjuster up
and down as needed until you
hear a click.
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.