GMC 2009 Envoy Denali Owner's Manual page 8

Power Lumbar
To increase or decrease support, hold the control
forward or rearward.
1-4
On vehicles with power
lumbar, the control is
located on the outboard
side of the seat.
Heated Seats
To heat the entire seat, press the horizontal button with
the heated seat and seatback symbol. Press the button to
cycle through the temperature settings of high, medium,
and low and to turn the heated seat off. The indicator
lights above the button will come on to designate the level
of heat selected: three for high, two for medium, and one
for low. The low setting warms the seatback and seat
cushion until the seat temperature is near body
temperature. The medium and high settings heat the
seatback and seat cushion to a slightly higher
temperature. You will be able to feel heat in about
two minutes.
Your vehicle may have
heated front seats. The
buttons used to control this
feature are located on the
front door armrests. The
engine must be running
for the heated seat feature
to work.