GMC 2008 Yukon Denali Owner's Manual page 17

Automatic Release Fold and Tumble
Feature
The transmission must be in PARK (P) for this feature
to work.
Folding and Tumbling the Seat(s)
CAUTION:
{
Automatically folding and tumbling the seat
when someone is sitting in the seat, could
cause injury to the person sitting there. Always
make sure there is no one sitting in the seat
before pressing the automatic seat release
button.
To fold and tumble the seat, 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.
Overhead Console
Buttons shown, Panel
Button similar
When accessing the third row seats, if your vehicle
has them, from the outside of the vehicle, press
the button on the panel behind either rear door.
One press of the button automatically folds
the seatback flat and tumbles the seat forward.
There will be a slight delay between the folding of
the seatback and the tumbling of the seat.
2. From the front seats,
press one of the
automatic seat release
buttons located on
the overhead console.
1-13