Page 12 of 511

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
In Brief 11
2. Slide the seat to the desiredposition and release the
handle.
3. Try to move the seat back and forth to be sure it is locked in
place.
See Seat Adjustment 057.
Power Seats
To adjust a power seat, if equipped:
.
Move the seat forward or
rearward by sliding the control
forward or rearward. .
If equipped, raise or lower the
front part of the seat cushion by
moving the front of the control
up or down.
. If equipped, raise or lower the
seat by moving the rear of the
control up or down.
See Power Seat Adjustment 058.
Lumbar Adjustment
Manual Lumbar
If equipped, move the lever up or
down repeatedly to increase or
decrease lumbar support.
See Lumbar Adjustment 058. Power Lumbar
To adjust the power lumbar support,
if equipped:
.
Press and hold the control
forward to increase or rearward
to decrease upper and lower
lumbar support at the same time.
. If equipped, press and hold the
control up to increase upper
lumbar support and decrease
lower lumbar support.
Press and hold the control down
to increase lower lumbar support
and decrease upper lumbar
support.
Page 58 of 511

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
Seats and Restraints 57
Rear Seats
The rear seat has adjustable
headrests in the outboard seating
positions.
The height of the headrest can be
adjusted. Pull the headrest up to
raise it. To lower the headrest, push
the headrest down.
If you are installing a child restraint
in the rear seat, see“Securing a
Child Restraint Designed for the
LATCH System” underLower
Anchors and Tethers for Children
(LATCH System) 095.
Front Seats
Seat Adjustment
{Warning
You can lose control of the
vehicle if you try to adjust a driver
seat while the vehicle is moving.
Adjust the driver seat only when
the vehicle is not moving.
To adjust a manual seat:
1. Pull the handle at the front of the seat.
2. Slide the seat to the desired position and release the
handle.
3. Try to move the seat back and forth to be sure it is locked in
place.
To adjust the seatback, see
Reclining Seatbacks 059.
To adjust the lumbar support,
if equipped, see Lumbar Adjustment
0 58.
Center Seat
If equipped, the center front
seatback doubles as an armrest and
cupholder/storage area for the driver
and passenger when the center
front seat is not used. Do not use it
as a seating position when the
seatback is folded down.
Page 59 of 511

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
58 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 equipped, raise or lower the
front part of the seat cushion by
moving the front of the control
up or down.
. If equipped, raise or lower the
seat by moving the rear of the
control up or down.
To adjust the seatback, see
Reclining Seatbacks 059. To adjust the lumbar support, see
Lumbar Adjustment
058.
Some vehicles are equipped with a
feature that activates a vibrating
pulse alert in the driver seat to help
the driver avoid crashes. See Driver
Assistance Systems 0305.
Lumbar Adjustment
Manual Lumbar
If equipped, move the lever up or
down repeatedly to increase or
decrease lumbar support.
Power Lumbar
To adjust the power lumbar support,
if equipped:
.
Press and hold the control
forward to increase or rearward
to decrease upper and lower
lumbar support at the same time.
. If equipped, press and hold the
control up to increase upper
lumbar support and decrease
lower lumbar support.
Press and hold the control down
to increase lower lumbar support
and decrease upper lumbar
support.