GMC 1995 Suburban Owner's Manual page 23

Power Lumbar Adjustment
To adjust the power
lumbar, press the front
of the lumbar switch
at the side of the seat.
Press the front of the
switch to increase
lumbar support. Press
the rear of the switch
to decrease lumbar
support.
As you press the back of the switch, you will hear air leaving the lumbar
support in the seatback.
Reclining Front Seatbacks
To adjust the seatback,
lift the front of this
lever.
Release the lever to lock the seatback where you want it. Pull up on the
front of the lever and the seatback will go to an upright position.
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