GMC TopKick 2007 Owner's Manual page 15

To adjust the height of the air suspension seat,
pull the lever up to inflate. Push the lever down
to deflate.
If your vehicle has an air suspension seat height
adjustment switch, it is located below the front
of the seat cushion on the inboard side of the seat.
Push the left side of the switch to inflate. Push
the right side of the switch to deflate.
Your seat cushion may also be able to be raised
or lowered.
To adjust the height of the cushion, lift the handle
up and pull it forward. You can choose between
two settings.
If your vehicle has this
feature, the seat cushion
height adjustment
handle is located
underneath the front
of the seat.
15