Chevrolet 2003 Avalanche Owner's Manual page 11

You can also reshape the back wing area of the lower
seatback.
To increase support in the wing area of the lower
seatback, press and hold the top of the control.
Let go of the control when the lower seatback
reaches the desired level of support.
To decrease support in the wing area of the lower
seatback, press and hold the bottom of the control.
Let go
of
the control when the lower seatback
reaches the desired level of support.
Heated Seats
a -
-
Your vehicle may have
heated front seats. The
buttons used to control this
feature are located on
the front doors. The engine
must be running for the
heated seat feature
to work.
To heat the entire seat, press the horizontal button with
the heated seat symbol. Press the button to cycle
through the temperature settings of high, medium and
low and to turn the heated seat off. Indicator lights
will glow to designate the level of heat selected, three
for high, two for medium, and one for low.
1 -4