lock GMC SIERRA 2021 Owner's Guide

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 47
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 048.
To adjust the lumbar support, if equipped,
see Lumbar Adjustment 048.
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.
Pull the strap on the side of the center
seatback to fold the center seatback. Do not
use the center seatback as a seating position
when the seatback is folded down.
To raise the seatback, push the seatback
rearward until it locks in the upright
position. Push and pull on the seatback to
make sure it is locked.
Power Seat Adjustment
To adjust a power seat, if equipped:
.Move the seat forward or rearward by
sliding the control forward or rearward.
.Raise or lower the front part of the seat
cushion by moving the front of the
control up or down.
.Raise or lower the seat by moving the
rear of the control up or down.
To adjust the seatback, see Reclining
Seatbacks 048.
To adjust the lumbar support, see Lumbar
Adjustment 048.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
48 Seats and Restraints
Some vehicles are equipped with a feature
that activates a vibrating pulse alert in the
driver seat to help the driver avoid crashes.
SeeDriver Assistance Systems 0265.
Lumbar Adjustment
Power Lumbar
To adjust the 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.
Reclining Seatbacks
{Warning
Sitting in a reclined position when the
vehicle is in motion can be dangerous.
Even when buckled up, the seat belts
cannot do their job.
The shoulder belt will not be against
your body. Instead, it will be in front of
you. In a crash, you could go into it,
receiving neck or other injuries.
The lap belt could go up over your
abdomen. The belt forces would be there,
not at your pelvic bones. This could cause
serious internal injuries.
For proper protection when the vehicle is
in motion, have the seatback upright.
Then sit well back in the seat and wear
the seat belt properly.
Do not have a seatback reclined if the
vehicle is moving.
Manual Reclining Seatbacks
{Warning
If either seatback is not locked, it could
move forward in a sudden stop or crash.
That could cause injury to the person
sitting there. Always push and pull on
the seatbacks to be sure they are locked.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 49
To adjust a manual seatback:1. Lift the lever. The seatback will automatically fold
forward.
2. To recline, move the seatback rearward to the desired position, then release the
lever to lock the seatback in place.
3. Push and pull on the seatback to make sure it is locked.
To return the seatback to the upright
position: 1. Lift the lever fully without applying pressure to the seatback, and the
seatback will return to the upright
position. 2. Push and pull on the seatback to make
sure it is locked.
Power Reclining Seatbacks
To recline a power seatback, if equipped:
.Tilt the top of the control rearward to
recline.
.Tilt the top of the control forward to
raise.
Memory Seats
If equipped, memory seats allow two drivers
to save and recall their unique seat positions
for driving the vehicle, and a shared exit
position for getting out of the vehicle. Other
feature positions may also be saved, such as
power mirrors, if equipped. Memory
positions are linked to RKE transmitter 1 or 2
for automatic memory recalls.
Before saving, adjust all available memory
feature positions. Turn the vehicle on and
then press and release SET; a beep will
sound. Then immediately press and hold 1,
2, or
B(Exit) until two beeps sound. To
manually recall these positions, press and

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
52 Seats and Restraints
Obstructions
If something has blocked the driver seat
while recalling a memory position, the recall
may stop. Remove the obstruction and try
the recall again. If the memory position still
does not recall, see your dealer.
Heated and Ventilated Front
Seats
{Warning
If temperature change or pain to the skin
cannot be felt, the seat heater may cause
burns. To reduce the risk of burns, use
care when using the seat heater,
especially for long periods of time. Do
not place anything on the seat that
insulates against heat, such as a blanket,
cushion, cover, or similar item. This may
cause the seat heater to overheat. An
overheated seat heater may cause a burn
or may damage the seat.Heated and Ventilated Seat Buttons Shown,Heated Seat Buttons Similar
If equipped, the buttons are on the center
stack. To operate, the engine must be
running.
Press
Ior+to heat the driver or
passenger seatback only.
Press
Jorzto heat the driver or
passenger seat cushion and seatback.
Press
Cor{to ventilate the driver or
passenger seat.
The indicator light on the button comes on
when this feature is on. Press the button once for the highest
setting. With each press of the button, the
seat will change to the next lower setting,
and then to the off setting. The indicator
lights next to the buttons indicate three for
the highest setting and one for the lowest.
If the heated seats are on high for an
extended time, their level may automatically
be lowered.
Auto Heated Seats
When the vehicle is on, this feature will
automatically activate the heated seats at
the level required by the vehicle’s interior
temperature. The active high, medium, low,
or off heated seat level will be indicated by
the manual heated seat buttons on the
center stack. Use the manual heated seat
buttons on the center stack to turn auto
heated seats off. If the passenger seat is
unoccupied, the auto heated seats feature
will not activate that seat. The auto heated
seats feature can be programmed to always
be enabled when the vehicle is on. See
Vehicle Personalization
0131.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
56 Seats and Restraints
.Wear the lap part of the belt low and
snug on the hips, just touching the
thighs. In a crash, this applies force to the
strong pelvic bones and you would be
less likely to slide under the lap belt.
If you slid under it, the belt would apply
force on your abdomen. This could cause
serious or even fatal injuries.
.Wear the shoulder belt over the shoulder
and across the chest. These parts of the
body are best able to take belt
restraining forces. The shoulder belt locks
if there is a sudden stop or crash.
{Warning
You can be seriously injured, or even
killed, by not wearing your seat belt
properly.
Never allow the lap or shoulder belt to
become loose or twisted.Never wear the shoulder belt under both
arms or behind your back.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 57
Always use the correct buckle for your
seating position.
Never route the lap or shoulder belt over an
armrest.
{Warning
The seat belt can be pinched if it is
routed under plastic trim on the seat,
such as trim around the rear seatback
folding handle or side airbag. In a crash,
pinched seat belts might not be able to
provide adequate protection. Never allow
seat belts to be routed under plastic trim
pieces.
Lap-Shoulder Belt
All seating positions in the vehicle have a
lap-shoulder belt.
The following instructions explain how to
wear a lap-shoulder belt properly.1. Adjust the seat, if the seat is adjustable, so you can sit up straight. To see how,
see “Seats” in the Index.2. Pick up the latch plate and pull the belt
across you. Do not let it get twisted.
The lap-shoulder belt may lock if you
pull the belt across you very quickly.
If this happens, let the belt go back
slightly to unlock it. Then pull the belt
across you more slowly.
If the shoulder portion of a passenger
belt is pulled out all the way, the child
restraint locking feature may be
engaged. See Child Restraint Systems
0 74. If this occurs, let the belt go back
all the way and start again. If the
locking feature stays engaged after
letting the belt go back to stowed

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
58 Seats and Restraints
position on the seat, move the seat
rearward or recline the seat until the
shoulder belt retractor lock releases.
Engaging the child restraint locking
feature in the front outboard seating
position may affect the passenger
sensing system, if equipped. See
Passenger Sensing System066.
If the webbing locks in the latch plate
before it reaches the buckle, tilt the latch
plate flat to unlock.
3. Push the latch plate into the buckle until
it clicks.
Pull up on the latch plate to make sure
it is secure. If the belt is not long
enough, see Seat Belt Extender 059.
Position the release button on the buckle
so that the seat belt could be quickly
unbuckled if necessary.4. To make the lap part tight, pull up on the shoulder belt.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 59
To unlatch the belt, push the button on the
buckle. The belt should return to its stowed
position.
Always stow the seat belt slowly. If the seat
belt webbing returns quickly to the stowed
position, the retractor may lock and cannot
be pulled out. If this happens, pull the seat
belt straight out firmly to unlock the
webbing, and then release it. If the webbing
is still locked in the retractor, see your
dealer.
Before a door is closed, be sure the seat belt
is out of the way. If a door is slammed
against a seat belt, damage can occur to
both the seat belt and the vehicle.
Seat Belt Pretensioners
This vehicle has seat belt pretensioners for
the front outboard occupants. Although the
seat belt pretensioners cannot be seen, they
are part of the seat belt assembly. They can
help tighten the seat belts during the early
stages of a moderate to severe frontal, near
frontal, or rear crash if the threshold
conditions for pretensioner activation are
met. Seat belt pretensioners can also help
tighten the seat belts in a side crash or
rollover event.Pretensioners work only once. If the
pretensioners activate in a crash, the
pretensioners and probably other parts of
the vehicle's seat belt system will need to
be replaced. See
Replacing Seat Belt System
Parts after a Crash 060.
Do not sit on the outboard seat belt while
entering or exiting the vehicle or at any
time while sitting in the seat. Sitting on the
seat belt can damage the webbing and
hardware.
Rear Seat Belt Comfort Guides
Rear seat belt comfort guides may provide
added seat belt comfort for older children
who have outgrown booster seats and for
some adults. When installed on a shoulder
belt, the comfort guide positions the
shoulder belt away from the neck and head.
Comfort guides are available through your
dealer for the rear outboard seating
positions. Instructions are included with the
comfort guides.
Seat Belt Use During Pregnancy
Seat belts work for everyone, including
pregnant women. Like all occupants, they
are more likely to be seriously injured if
they do not wear seat belts.
A pregnant woman should wear a
lap-shoulder belt, and the lap portion should
be worn as low as possible, below the
rounding, throughout the pregnancy.
The best way to protect the fetus is to
protect the mother. When a seat belt is
worn properly, it is more likely that the
fetus will not be hurt in a crash. For
pregnant women, as for anyone, the key to
making seat belts effective is wearing them
properly.
Seat Belt Extender
If the vehicle's seat belt will fasten around
you, you should use it.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 63
Driver Side Shown, Passenger Side Similar
The driver and front outboard passenger
seat-mounted side impact airbags are in the
side of the seatbacks closest to the door.Driver Side Crew Cab Shown, Passenger Side Double and Regular Cabs Similar
The roof-rail airbags for the driver, front
outboard passenger, and second row
outboard passengers are in the ceiling above
the side windows.
{Warning
If something is between an occupant and
an airbag, the airbag might not inflate
properly or it might force the object into
that person causing severe injury or even
death. The path of an inflating airbag
must be kept clear. Do not put anything
between an occupant and an airbag, and (Continued)
Warning (Continued)
do not attach or put anything on the
steering wheel hub or on or near any
other airbag covering.
Do not use seat accessories that block the
inflation path of a seat-mounted side
impact airbag.
Never secure anything to the roof of a
vehicle with roof-rail airbags by routing a
rope or tie‐down through any door or
window opening. If you do, the path of
an inflating roof-rail airbag will be
blocked.
When Should an Airbag Inflate?
This vehicle is equipped with airbags. See
Airbag System061. Airbags are designed to
inflate if the impact exceeds the specific
airbag system's deployment threshold.
Deployment thresholds are used to predict
how severe a crash is likely to be in time
for the airbags to inflate and help restrain
the occupants. The vehicle has electronic
sensors that help the airbag system
determine the severity of the impact.
Deployment thresholds can vary with
specific vehicle design.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 65
What Will You See after an
Airbag Inflates?
After frontal and seat-mounted side impact
airbags inflate, they quickly deflate, so
quickly that some people may not even
realize the airbags inflated. Roof-rail airbags
may still be at least partially inflated for
some time after they inflate. Some
components of the airbag module may be
hot for several minutes. For location of the
airbags, seeWhere Are the Airbags? 062.
The parts of the airbag that come into
contact with you may be warm, but not too
hot to touch. There may be some smoke
and dust coming from the vents in the
deflated airbags. Airbag inflation does not
prevent the driver from seeing out of the
windshield or being able to steer the
vehicle, nor does it prevent people from
leaving the vehicle.
{Warning
When an airbag inflates, there may be
dust in the air. This dust could cause
breathing problems for people with a
history of asthma or other breathing
trouble. To avoid this, everyone in the (Continued)
Warning (Continued)
vehicle should get out as soon as it is
safe to do so. If you have breathing
problems but cannot get out of the
vehicle after an airbag inflates, then get
fresh air by opening a window or a door.
If you experience breathing problems
following an airbag deployment, you
should seek medical attention.
The vehicle has a feature that may
automatically unlock the doors, turn on the
interior lamps and hazard warning flashers,
and shut off the fuel system after the
airbags inflate. The feature may also
activate, without airbag inflation, after an
event that exceeds a predetermined
threshold. After turning the ignition off and
then on again, the fuel system will return to
normal operation; the doors can be locked,
the interior lamps can be turned off, and
the hazard warning flashers can be turned
off using the controls for those features.
If any of these systems are damaged in the
crash they may not operate as normal.
{Warning
A crash severe enough to inflate the
airbags may have also damaged
important functions in the vehicle, such
as the fuel system, brake and steering
systems, etc. Even if the vehicle appears
to be drivable after a moderate crash,
there may be concealed damage that
could make it difficult to safely operate
the vehicle.
Use caution if you should attempt to
restart the engine after a crash has
occurred.
In many crashes severe enough to inflate
the airbag, windshields are broken by
vehicle deformation. Additional windshield
breakage may also occur from the front
outboard passenger airbag.
.Airbags are designed to inflate only once.
After an airbag inflates, you will need
some new parts for the airbag system.
If you do not get them, the airbag
system will not be there to help protect
you in another crash. A new system will
include airbag modules and possibly other
parts. The service manual for the vehicle
covers the need to replace other parts.