GMC 2004 Sierra 1500 Pickup Owner's Manual page 11

Power Lumbar
You can increase or
decrease lumbar support
in an area of the lower
seatback.
To increase support, press and hold the front of the
control. To decrease support, press and hold the rear of
the control. Let go of the control when the lower
seatback reaches the desired level of support.
You can also reshape the side wing area of the lower
seatback for more lateral support.
To increase support, press and hold the top of the
control. To decrease support, press and hold the bottom
of the control. Let go of the control when the lower
seatback reaches the desired level of support.
Your vehicle may have a memory function which allows
seat settings to be saved and recalled. See Memory
Seat on page 2-69 for more information.
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