GMC Yukon Owner's Manual page 45

Power Lumbar
On seats with power lumbar, the controls used to
operate this feature are located on the outboard side
of the seats.
This vehicle may have 2 way lumbar.
To increase lumbar support, press and hold the top
of the control.
To decrease lumbar support, press and hold the
bottom of the control.
The vehicle may have 4 way lumbar.
To increase lumbar support, press and hold the
front of the control.
To decrease lumbar support, press and hold the
rear of the control.
To raise the height of the lumbar support, press
and hold the top of the control.
To lower the height of the lumbar support, press
and hold the bottom of the control.
Release the control when the lower seatback reaches
the desired level of lumbar support.
Your vehicle may have a memory function which allows
seat settings to be saved and recalled. See Memory
Seat, Mirrors, and Pedals on page 2 10 for more
information.
Keep in mind that as your seating position changes, as
it may during long trips, so should the position of your
lumbar support. Adjust the seat as needed.
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