GMC Yukon Denalid Owner's Manual page 24

CAUTION:
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A safety belt that is improperly routed,
not properly attached, or twisted will not
provide the protection needed in a crash.
The person wearing the belt could be
seriously injured. After raising the rear
seatback, always check to be sure that
the safety belts are properly routed and
attached, and are not twisted.
3. Make sure that the safety belt in the center
seating position is not caught between the
two seats and is not twisted.
24
Folding and Tumbling the Second Row
Seat(s) from the Third Row Seats or
Outside
CAUTION:
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Using the third row seating position while
the second row is folded, or folded and
tumbled, could cause injury in a sudden
stop or crash. Be sure to return the seat
to the passenger seating position. Push
and pull on the seat to make sure it is
locked into place.
To fold and tumble the seat from the third row
seats, if your vehicle has them, do the following:
1. Make sure that there is nothing under, in front
of, or on the seat.
Notice: Folding a rear seat with the safety
belts still fastened may cause damage to the
seat or the safety belts. Always unbuckle
the safety belts and return them to their normal
stowed position before folding a rear seat.