GMC 2004 Sierra 1500 Pickup Owner's Manual page 71

In addition to the air bag off switch, your vehicle may
have the passenger sensing system. The passenger
sensing system is designed to turn off the right
front passenger's frontal air bag when an infant or small
child in a rear-facing infant seat, a forward-facing
child restraint, or a booster seat is detected. In addition
to the passenger sensing system, you may use the
air bag off switch located on the instrument panel to turn
the air bag off. See Air Bag Off Switch on page 1-76
and Passenger Sensing System on page 1-81 .
Never put a rear facing child restraint in the right front
passenger's seat unless the air bag is off. Here is why:
{
CAUTION:
A child in a rear-facing child restraint can be
seriously injured or killed if the right front
passenger's air bag inflates. This is because the
back of the rear-facing child restraint would be
very close to the inflating air bag. Be sure the air
bag is off before using a rear-facing child
restraint in the right front seat position. If you
secure a forward-facing child restraint in the
right front seat, always move the right front
passenger seat as far back as it will go.
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