GMC 2015 Sierra Denali Owner's Manual page 67

3-14 Seats and Restraints
Adjust the height so the shoulder
portion of the belt is on the shoulder
and not falling off of it. The belt
should be close to, but not
contacting, the neck. Improper
shoulder belt height adjustment
could reduce the effectiveness of
the safety belt in a crash. See How
to Wear Safety Belts Properly on
page 3-11.
Push down on the release button to
move the height adjuster to the
desired position.
Move the adjuster up by pushing up
on the shoulder belt guide.
After the adjuster is set to the
desired position, try to move it down
without pushing the release button
to make sure it has locked into
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, near
frontal, or rear 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. If the vehicle has rollover
capable roof-rail airbags, safety belt
pretensioners can help tighten the
safety belts in a rollover event.
Pretensioners work only once. If the
pretensioners activate in a crash,
they will need to be replaced, and
the vehicle s safety belt system will
probably need other new parts. See
Replacing Safety Belt System Parts
after a Crash on page 3-16.
Rear Safety Belt Comfort
Guides
Warning
A safety belt that is not properly
worn may not provide the
protection needed in a crash. The
person wearing the belt could be
seriously injured. The shoulder
belt should go over the shoulder
and across the chest. These parts
of the body are best able to take
belt restraining forces.