GMC Yukon XL 2013 Owner's Manual page 62

3-4 Seats and Restraints
Power Seat Adjustment
To adjust a power seat, if equipped:
Move the seat forward or
rearward by sliding the control
forward or rearward.
If available, raise or lower the
front or rear part of the seat
cushion by moving the front or
rear of the control up or down.
If available, raise or lower the
entire seat by moving the entire
control up or down.
To adjust the seatback, see Power
Reclining Seatbacks under
Reclining Seatbacks on page 3 5.
Lumbar Adjustment
Manual Lumbar
If equipped, increase or decrease
manual lumbar support by turning
the knob forward or rearward.