GMC 2004 Yukon XL Owner's Manual page 88

The passenger sensing system works with sensors that
are part of the right front passenger's seat and safety
belt. The sensors are designed to detect the presence
of a properly-seated occupant and determine if the
passenger's frontal air bag should be enabled
(may inflate) or not.
Accident statistics show that children are safer if they
are restrained in the rear rather than the front seat.
General Motors recommends that child restraints
be secured in a rear seat, including an infant riding in a
rear-facing infant seat, a child riding in a forward-facing
child seat and an older child riding in a booster seat.
Your vehicle has a rear seat that will accommodate
a rear-facing child restraint. A label on your sun visor
says, "Never put a rear-facing child seat in the front."
This is because the risk to the rear-facing child is
so great, if the air bag deploys.
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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.
Even though the passenger sensing system
is designed to turn off the passenger's frontal
air bag if the system detects a rear-facing
child restraint, no system is fail-safe, and no
one can guarantee that an air bag will not
deploy under some unusual circumstance,
even though it is turned off. General Motors
recommends that rear-facing child restraints
be secured in the rear seat, even if the air bag
is off.