Chevrolet 2009 Impala Owner's Manual page 33

Shoulder Belt Height Adjuster
The vehicle has shoulder belt height adjusters for the
driver and right front passenger positions.
Adjust the height so that the shoulder portion of the belt
is centered on the shoulder. The belt should be away
from the face and neck, but not falling off the shoulder.
Improper shoulder belt height adjustment could
reduce the effectiveness of the safety belt in a crash.
You can move the adjuster up just by pushing up on the
shoulder belt guide.
After the adjuster is set to the desired position, try to
move it down without squeezing the buttons to
make sure it has locked into position.
Squeeze the buttons (A)
on the sides of the height
adjuster and move the
height adjuster to the
desired position.
Safety Belt Pretensioners
This vehicle has safety belt pretensioners for front
outboard occupants. Although the safety belt
pretensioners cannot be seen, they are part of the
safety belt assembly. They can help tighten the safety
belts during the early stages of a moderate to severe
frontal and near frontal crash if the threshold conditions
for pretensioner activation are met. And, if the vehicle
has side impact airbags, safety belt pretensioners
can help tighten the safety belts in a side crash.
Pretensioners work only once. If the pretensioners
activate in a crash, they will need to be replaced, and
probably other new parts for the vehicle's safety
belt system. See Replacing Restraint System Parts
After a Crash on page 1-74.
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