GMC 2003 Sonoma Owner's Manual page 12

Power Lumbar
If your vehicle has this
feature, there will be a
control located on
the outboard side of the
front seat(s).
Heated Seats
Press and hold the front of the control until you have
the desired lumbar support. To decrease lumbar
support, press and hold the rear of the control.
If your vehicle has this
feature, the controls are
located on the outboard
side of the front seats.
This feature will quickly heat the lower cushion and
lower back of the driver's and front passenger's seats
for added comfort.
Press the lower part of the switch to turn the heater
on
low. Press the upper part of the switch to turn the
heater on high. Put the switch in the center position to
turn the heater off.
The passenger's safety belt must be engaged for the
heated seat feature to work on the passenger's seat.
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