Hummer H2 2009 Owner's Manual page 14

Rear Seats
Heated Seats
Driver Side RSA Heated
Seat Button shown
1-10
On vehicles with rear
outboard heated seats, the
buttons used to control this
feature are located on the
Rear Seat Audio (RSA)
panel.
M
(Heated Seat): To heat the seat cushion, press the
button with the heated seat symbol.
A heated seat symbol will be shown in the RSA display to
indicate that the feature is on. Press the button to cycle
through the temperature settings of high, medium, and
low, and to turn it off. Indicator bars next to the symbol
will designate the level of heat selected: three for high,
two for medium, and one for low.
The heated seats are off when the ignition is off.