2018 GMC SIERRA service

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
84 Seats and Restraints
an airbag system will not work
properly. See your dealer for
service.
Airbag On-Off Switch
If the passenger side instrument
panel endcap has the switch
pictured in the following illustration,
the vehicle has an airbag on-off
switch that you can use to manually
turn on or off the front outboard
passenger frontal airbag. See
Instrument Panel06.
If the vehicle does not have an
airbag on-off switch, it may have a
passenger sensing system. See
Passenger Sensing System 086. This switch should only be turned to
the off position if the person in the
front outboard passenger position is
a member of a passenger risk group
identified by the national
government as follows:
Infant. An infant (less than 1 year
old) must ride in the front seat
because:
.
My vehicle has no rear seat;
. My vehicle has a rear seat too
small to accommodate a
rear-facing infant seat; or
. The infant has a medical
condition which, according to the
infant's physician, makes it
necessary for the infant to ride in
the front seat so that the driver
can constantly monitor the
child's condition.
Child age 1 to 12. A child
age 1 to 12 must ride in the front
seat because:
. My vehicle has no rear seat;
. Although children ages 1 to 12
ride in the rear seat(s) whenever
possible, children ages 1 to 12 sometimes must ride in the front
because no space is available in
the rear seat(s) of my vehicle; or
. The child has a medical
condition which, according to the
child's physician, makes it
necessary for the child to ride in
the front seat so that the driver
can constantly monitor the
child's condition.
Medical Condition. A passenger
has a medical condition which,
according to his or her physician:
. Causes the passenger airbag to
pose a special risk for the
passenger; and
. Makes the potential harm from
the passenger airbag in a crash
greater than the potential harm
from turning off the airbag and
allowing the passenger, even if
belted, to hit the instrument
panel or windshield in a crash.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Seats and Restraints 85
{Warning
If the front outboard passenger
frontal airbag is turned off for a
person who is not in a risk group
identified by the national
government, that person will not
have the extra protection of an
airbag. In a crash, the airbag will
not be able to inflate and help
protect the person sitting there.
Do not turn off the front outboard
passenger frontal airbag unless
the person sitting there is in a risk
group.
To turn off the front outboard
passenger frontal airbag, insert the
ignition key into the switch, push in,
and move the switch to the off
position.
The word OFF or the off symbol will
come on in the passenger airbag
status indicator located in the
overhead console to let you know
that the front outboard passenger
frontal airbag is off, after the system
check is completed. The airbag off
light will come on and stay on to let
you know that the front outboard
passenger frontal airbag is off. See
Airbag On-Off Light0147. The front
outboard passenger airbag will
remain off until you turn it back on
again.
{Warning
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
with the airbag system. For
example, the front outboard
(Continued)
Warning (Continued)
passenger frontal airbag could
inflate even though the airbag
on-off switch is turned off.
To help avoid injury to yourself or
others, have the vehicle serviced
right away. SeeAirbag Readiness
Light 0147 for more information,
including important safety
information.
To turn the front outboard passenger
frontal airbag on again, insert the
ignition key into the switch, push in,
and move the switch to the on
position.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
88 Seats and Restraints
wear a seat belt properly—whether
or not there is an airbag for that
person.
{Warning
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
with the airbag system. To help
avoid injury to yourself or others,
have the vehicle serviced right
away. See Airbag Readiness
Light 0147 for more information,
including important safety
information.
If the On Indicator Is Lit for a
Child Restraint
The passenger sensing system is
designed to turn off the front
outboard passenger frontal airbag if
the system determines that an infant
is present in a child restraint. If a
child restraint has been installed
and the on indicator is lit:
1. Turn the vehicle off. 2. Remove the child restraint from
the vehicle.
3. Remove any additional items from the seat such as blankets,
cushions, seat covers, seat
heaters, or seat massagers.
4. Reinstall the child restraint following the directions
provided by the child restraint
manufacturer and refer to
Securing Child Restraints (With
the Seat Belt in the Center
Front Seat) 0114 orSecuring
Child Restraints (With the Seat
Belt in the Front Passenger
Seat) 0115 orSecuring Child
Restraints (With the Seat Belt
in the Rear Seat) 0111.
Make sure the seat belt
retractor is locked by pulling
the shoulder belt all the way
out of the retractor when
installing the child restraint,
even if the child restraint is
equipped with a seat belt lock
off. When the retractor lock is
set, the belt can be tightened
but not pulled out of the
retractor. 5. If, after reinstalling the child
restraint and restarting the
vehicle, the on indicator is still
lit, turn the vehicle off. Then
slightly recline the vehicle
seatback and adjust the seat
cushion, if adjustable, to make
sure that the vehicle seatback
is not pushing the child
restraint into the seat cushion.
Also make sure the child
restraint is not trapped under
the vehicle head restraint.
If this happens, adjust the head
restraint. See Head Restraints
0 58.
6. Restart the vehicle.
The passenger sensing system may
or may not turn off the airbag for a
child in a child restraint depending
upon the child’s size. It is better to
secure child restraints in the rear
seat. Consider using another
vehicle to transport the child when a
rear seat is not available. Never put
a rear-facing child restraint in the
front seat, even if the on indicator is
not lit.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
90 Seats and Restraints
A thick layer of additional material,
such as a blanket or cushion,
or aftermarket equipment such as
seat covers, seat heaters, and seat
massagers can affect how well the
passenger sensing system
operates. We recommend that you
not use seat covers or other
aftermarket equipment except when
approved by GM for your specific
vehicle. SeeAdding Equipment to
the Airbag-Equipped Vehicle 090
for more information about
modifications that can affect how
the system operates.
The on indicator may be lit if an
object, such as a briefcase,
handbag, grocery bag, laptop,
or other electronic device, is put on
an unoccupied seat. If this is not
desired, remove the object from
the seat.
{Warning
Stowing articles under the
passenger seat or between the
passenger seat cushion and
(Continued)
Warning (Continued)
seatback may interfere with the
proper operation of the passenger
sensing system.
Servicing the
Airbag-Equipped Vehicle
Airbags affect how the vehicle
should be serviced. There are parts
of the airbag system in several
places around the vehicle. Your
dealer and the service manual have
information about servicing the
vehicle and the airbag system. To
purchase a service manual, see
Service Publications Ordering
Information0474.
{Warning
For up to 10 seconds after the
vehicle is turned off and the
battery is disconnected, an airbag
can still inflate during improper
service. You can be injured if you
(Continued)
Warning (Continued)
are close to an airbag when it
inflates. Avoid yellow connectors.
They are probably part of the
airbag system. Be sure to follow
proper service procedures, and
make sure the person performing
work for you is qualified to do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the
vehicle's frame, bumper system,
height, front end, or side sheet
metal, may keep the airbag system
from working properly.
The operation of the airbag system
can also be affected by changing
any parts of the front seats, seat
belts, airbag sensing and diagnostic
module, steering wheel, instrument
panel, inner door seals including the
speakers, any of the airbag
modules, ceiling or pillar garnish

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Seats and Restraints 91
trim, overhead console, front
sensors, side impact sensors,
or airbag wiring.
Your dealer and the service manual
have information about the location
of the airbag sensors, sensing and
diagnostic module, and airbag
wiring.
In addition, the vehicle may have a
passenger sensing system for the
front outboard passenger position,
which includes sensors that are part
of the passenger’s seat. The
passenger sensing system may not
operate properly if the original seat
trim is replaced with non-GM
covers, upholstery, or trim; or with
GM covers, upholstery, or trim
designed for a different vehicle. Any
object, such as an aftermarket seat
heater or a comfort-enhancing pad
or device, installed under or on top
of the seat fabric, could also
interfere with the operation of the
passenger sensing system. This
could either prevent proper
deployment of the passenger
airbag(s) or prevent the passenger
sensing system from properly turning off the passenger airbag(s).
See
Passenger Sensing System
0 86.
If the vehicle has rollover roof-rail
airbags, see Different Size Tires
and Wheels 0409 for additional
important information.
If a snow plow is added to the
vehicle, the airbags should still work
properly. The airbag systems were
designed to work properly under a
wide range of conditions, including
snow plowing with vehicles that
have the optional snow plow prep
package (RPO VYU). Do not
change or defeat the snow plow's
“tripping mechanism.” If you do, it
can damage the snow plow and the
vehicle, and may cause an airbag
deployment.
If you have to modify your vehicle
because you have a disability and
you have questions about whether
the modifications will affect the
vehicle's airbag system, or if you
have questions about whether the
airbag system will be affected if the
vehicle is modified for any other reason, call Customer Assistance.
See
Customer Assistance Offices
0 467.
Airbag System Check
The airbag system does not need
regularly scheduled maintenance or
replacement. Make sure the airbag
readiness light is working. See
Airbag Readiness Light 0147.
Caution
If an airbag covering is damaged,
opened, or broken, the airbag
may not work properly. Do not
open or break the airbag
coverings. If there are any
opened or broken airbag
coverings, have the airbag
covering and/or airbag module
replaced. For the location of the
airbags, see Where Are the
Airbags? 078. See your dealer
for service.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
92 Seats and Restraints
Replacing Airbag System
Parts after a Crash
{Warning
A crash can damage the airbag
systems in the vehicle.
A damaged airbag system may
not properly protect you and your
passenger(s) in a crash, resulting
in serious injury or even death. To
help make sure the airbag
systems are working properly
after a crash, have them
inspected and any necessary
replacements made as soon as
possible.
If an airbag inflates, you will need to
replace airbag system parts. See
your dealer for service.
If the airbag readiness light stays on
after the vehicle is started or comes
on when you are driving, the airbag
system may not work properly. Have
the vehicle serviced right away. See
Airbag Readiness Light 0147.
Child Restraints
Older Children
Older children who have outgrown
booster seats should wear the
vehicle’s seat belts.
The manufacturer instructions that
come with the booster seat state the
weight and height limitations for that
booster. Use a booster seat with a
lap-shoulder belt until the child
passes the fit test below: .
Sit all the way back on the seat.
Do the knees bend at the seat
edge? If yes, continue. If no,
return to the booster seat.
. Buckle the lap-shoulder belt.
Does the shoulder belt rest on
the shoulder? If yes, continue.
If no, try using the rear seat belt
comfort guide, if available. See
“Rear Seat Belt Comfort Guides”
under Lap-Shoulder Belt 071.
If a comfort guide is not
available, or if the shoulder belt
still does not rest on the
shoulder, then return to the
booster seat.
. Does the lap belt fit low and
snug on the hips, touching the
thighs? If yes, continue. If no,
return to the booster seat.
. Can proper seat belt fit be
maintained for the length of the
trip? If yes, continue. If no,
return to the booster seat.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
118 Seats and Restraints
If a child restraint has been installed
and the on indicator is lit, see“If the
On Indicator Is Lit for a Child
Restraint” underPassenger Sensing
System 086.
To remove the child restraint,
unbuckle the vehicle seat belt and
let it return to the stowed position.
If the top tether is attached to a top
tether anchor, disconnect it.
With Airbag On-Off Switch
This vehicle has airbags. A rear
seat is a safer place to secure a
forward-facing child restraint. See
Where to Put the Restraint 098.
There may be a switch on the
instrument panel endcap that you
can use to turn off the front
outboard passenger frontal airbag.
See Airbag On-Off Switch 084 for
more information, including
important safety information.
Never put a rear-facing child
restraint in the front. This is because
the risk to the rear-facing child is so
great if the airbag deploys.
{Warning
A child in a rear-facing child
restraint can be seriously injured
or killed if the front outboard
passenger airbag inflates. This is
because the back of the
rear-facing child restraint would
be very close to the inflating
airbag. A child in a forward-facing
child restraint can be seriously
injured or killed if the front
outboard passenger airbag
inflates and the passenger seat is
in a forward position.
Even if the airbag switch has
turned off the front outboard
passenger frontal airbag, no
system is fail-safe. No one can
guarantee that an airbag will not
deploy under some unusual
circumstance, even though it is
turned off.
Secure rear-facing child restraints
in a rear seat, even if the airbag
is off. If you secure a
(Continued)
Warning (Continued)
forward-facing child restraint in
the front outboard passenger
seat, always move the seat as far
back as it will go. It is better to
secure the child restraint in a
rear seat.
{Warning
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
with the airbag system. For
example, the front outboard
passenger frontal airbag could
inflate even though the airbag
on-off switch is turned off.
To help avoid injury to yourself or
others, have the vehicle serviced
right away. SeeAirbag Readiness
Light 0147 for more information,
including important safety
information.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
132 Instruments and Controls
Clock
Setting the Time and Date with
Faceplate Controls
To set the time or date:1. Select SETTINGS from the Home Page, then select Time
and Date.
2. Select the desired function.
3. Turn the MENU knob to increase or decrease the value.
4. Press the MENU knob to go to the next value. After the last
value is selected, the system
will update and return to the
Settings menu. Press
oBACK
to go to the last menu and
save the changes.
Auto Set requires an active OnStar
service plan.
If auto timing is set, the time
displayed on the clock may not
update immediately when driving
into a new time zone. To set the clock display:
1. Select SETTINGS from the Home Page, then select Time
and Date.
2. Select Clock Display.
3. Turn the MENU knob to Off or On.
4. Press the MENU knob to select.
Press
oBACK to go to the last
menu and save the changes.
Setting the Time and Date with
Touchscreen Controls
To set the time:
1. Touch SETTINGS from the Home Page, then touch Time
and Date.
2. Touch Set Time and touch
«
orªto increase or decrease
hours, minutes, and AM or PM.
Touch 12–24 Hr for 12 or
24 hour clock. 3. Touch the
}or0screen
button to go back to the
previous menu.
Auto Set requires an active OnStar
service plan.
If auto timing is set, the time
displayed on the clock may not
update immediately when driving
into a new time zone.
To set the date: 1. Touch SETTINGS from the Home Page, then touch Time
and Date.
2. Touch Set Date and touch
«
orªto increase or decrease
month, day, or year.
3. Touch the
}or0screen
button to go back to the
previous menu.
To set the clock display:
1. Touch SETTINGS and touch Time and Date.
2. Touch Clock Display and touch OFF or ON to turn the clock
display off or on.