2008 GMC SIERRA roof

Seats and Restraint Systems........................... 1-1
Front Seats
............................................... 1-3
Rear Seats
..............................................1-12
Safety Belts
.............................................1-14
Child Restraints
.......................................1-35
Airbag System
.........................................1-68
Restraint System Check
............................1-87
Features and Controls..................................... 2-1
Keys
........................................................ 2-3
Doors and Locks
......................................2-10
Windows
.................................................2-15
Theft-Deterrent Systems
............................2-18
Starting and Operating Your Vehicle
...........2-22
Mirrors
....................................................2-55
Object Detection Systems
..........................2-63
OnStar
®System
......................................2-65
Universal Home Remote System
................2-68
Storage Areas
.........................................2-74
Sunroof
..................................................2-79
Instrument Panel............................................. 3-1
Instrument Panel Overview
.......................... 3-4
Climate Controls
......................................3-25
Warning Lights, Gages, and Indicators
........3-34
Driver Information Center (DIC)
..................3-54
Audio System(s)
.......................................3-80Driving Your Vehicle....................................... 4-1
Your Driving, the Road, and Your Vehicle
..... 4-2
Towing
...................................................4-50
Service and Appearance Care.......................... 5-1
Service
..................................................... 5-4
Fuel
......................................................... 5-6
Checking Things Under the Hood
...............5-12
Rear Axle
...............................................5-51
Four-Wheel Drive
.....................................5-52
Front Axle
...............................................5-54
Noise Control System
...............................5-56
Headlamp Aiming
.....................................5-56
Bulb Replacement
....................................5-59
Windshield Wiper Blade Replacement
.........5-65
Tires
......................................................5-66
Appearance Care
...................................5-112
Vehicle Identication
...............................5-121
Electrical System
....................................5-122
Capacities and Specications
...................5-130
Maintenance Schedule..................................... 6-1
Maintenance Schedule
................................ 6-2
Customer Assistance Information.................... 7-1
Customer Assistance and Information
........... 7-2
Reporting Safety Defects
...........................7-14
Vehicle Data Recording and Privacy
...........7-16
Index................................................................ 1
2008 GMC Sierra Owner ManualM

6. To tighten the belt, push down on the child restraint,
pull the shoulder portion of the belt to tighten the
lap portion of the belt and feed the shoulder
belt back into the retractor. If you are using a
forward-facing child restraint, you may nd it helpful
to use your knee to push down on the child
restraint as you tighten the belt.
7. If your child restraint has a top tether, follow the
child restraint manufacturer’s instructions regarding
the use of the top tether. SeeLower Anchors
and Tethers for Children (LATCH) on page 1-45for
more information.8. Push and pull the child restraint in different
directions to be sure it is secure.
To remove the child restraint, unbuckle the vehicle’s
safety belt and let it go back all the way. If the top tether
is attached to a top tether anchor, disconnect it.
Airbag System
Your vehicle has the following airbags:
A frontal airbag for the driver.
A frontal airbag for the right front passenger.
Your vehicle may have the following airbags:
A roof-rail airbag for the driver and the passenger
seated directly behind the driver.
A roof-rail airbag for the right front passenger and
the person seated directly behind the right front
passenger.
All of the airbags in your vehicle will have the word
AIRBAG embossed in the trim or on an attached label
near the deployment opening.
For frontal airbags, the word AIRBAG will appear on the
middle part of the steering wheel for the driver and
on the instrument panel for the right front passenger.
With roof-rail airbags, the word AIRBAG will appear
along the headliner or trim.
1-68

Airbags are designed to supplement the protection
provided by safety belts. Even though today’s airbags
are also designed to help reduce the risk of injury
from the force of an inating bag, all airbags must inate
very quickly to do their job.
Here are the most important things to know about the
airbag system:
{CAUTION:
You can be severely injured or killed in a crash
if you are not wearing your safety belt — even
if you have airbags. Wearing your safety belt
during a crash helps reduce your chance of
hitting things inside the vehicle or being
ejected from it. Airbags are “supplemental
restraints” to the safety belts. All airbags are
designed to work with safety belts, but do not
replace them.
{CAUTION:
Frontal airbags are designed to deploy in
moderate to severe frontal and near frontal
crashes. They are not designed to inate in
rollover, rear crashes, or in many side crashes.
If your vehicle has rollover capable roof-rail
airbags, they are designed to inate in
moderate to severe crashes where something
hits the side of your vehicle, during a vehicle
rollover, or in a severe frontal impact. They are
not designed to inate in rear crashes.
Everyone in your vehicle should wear a safety
belt properly — whether or not there is an
airbag for that person.
1-69

{CAUTION:
Airbags inate with great force, faster than the
blink of an eye. Anyone who is up against, or
very close to, any airbag when it inates can
be seriously injured or killed. Do not sit
unnecessarily close to the airbag, as you
would be if you were sitting on the edge of
your seat or leaning forward. Safety belts help
keep you in position before and during a
crash. Always wear your safety belt, even with
airbags. The driver should sit as far back as
possible while still maintaining control of the
vehicle.
Occupants should not lean on or sleep against
the door or side windows in seating positions
with roof-rail airbags.
{CAUTION:
Airbags plus lap-shoulder belts offer the best
protection for adults, but not for young
children and infants. Neither the vehicle’s
safety belt system nor its airbag system is
designed for them. Young children and infants
need the protection that a child restraint
system can provide. Always secure children
properly in your vehicle. To read how, see
Older Children on page 1-35orInfants and
Young Children on page 1-38.
There is an airbag
readiness light on the
instrument panel cluster,
which shows the airbag
symbol.
The system checks the airbag electrical system for
malfunctions. The light tells you if there is an electrical
problem. SeeAirbag Readiness Light on page 3-38
for more information.
1-70

If your vehicle has roof-rail airbags for the driver, right
front passenger, and second row outboard passengers,
they are in the ceiling above the side windows.
{CAUTION:
If something is between an occupant and an
airbag, the airbag might not inate properly or
it might force the object into that person
causing severe injury or even death. The path
of an inating airbag must be kept clear. Do
not put anything between an occupant and an
airbag, and do not attach or put anything on
the steering wheel hub or on or near any other
airbag covering.
If your vehicle has roof-rail airbags, never
secure anything to the roof of your vehicle by
routing the rope or tie down through any door
or window opening. If you do, the path of an
inating roof-rail airbag will be blocked. Driver Side shown, Passenger Side similar
1-72

Vehicles with dual stage airbags also have seat position
sensors which enables the sensing system to monitor
the position of the driver’s seat. The seat position sensor
provides information that is used to determine if the
airbags should deploy at a reduced level or at full
deployment.
Your vehicle may or may not have roof-rail airbags. See
Airbag System on page 1-68. Roof-rail airbags are
intended to inate in moderate to severe side crashes.
In addition, these roof-rail airbags are intended to
inate during a rollover or in a severe frontal impact.
Roof-rail airbags will inate if the crash severity is above
the system’s designed threshold level. The threshold
level can vary with specic vehicle design.
Roof-rail airbags are not intended to inate in rear
impacts. Both roof-rail airbags will deploy when either
side of the vehicle is struck, or if the sensing system
predicts that the vehicle is about to roll over, or in
a severe frontal impact.
In any particular crash, no one can say whether an
airbag should have inated simply because of the
damage to a vehicle or because of what the repair costs
were. For frontal airbags, ination is determined by
what the vehicle hits, the angle of the impact, and how
quickly the vehicle slows down. For roof-rail airbags,
deployment is determined by the location and severity of
the side impact. In a rollover event, roof-rail airbag
deployment is determined by the direction of the roll.What Makes an Airbag Inate?
In a deployment event, the sensing system sends an
electrical signal triggering a release of gas from
the inator. Gas from the inator lls the airbag causing
the bag to break out of the cover and deploy. The
inator, the airbag, and related hardware are all part of
the airbag module.
Frontal airbag modules are located inside the steering
wheel and instrument panel. For vehicles with
roof-rail airbags, there are airbag modules in the ceiling
of the vehicle, near the side windows that have
occupant seating positions.
How Does an Airbag Restrain?
In moderate to severe frontal or near frontal collisions,
even belted occupants can contact the steering wheel or
the instrument panel. In moderate to severe side
collisions, even belted occupants can contact the inside
of the vehicle.
Airbags supplement the protection provided by safety
belts. Frontal airbags distribute the force of the
impact more evenly over the occupant’s upper body,
stopping the occupant more gradually. Roof-rail airbags
distribute the force of the impact more evenly over
the occupant’s upper body.
1-74

Rollover capable roof-rail airbags are designed to help
contain the head and chest of occupants in the
outboard seating positions in the rst and second rows.
The rollover capable roof-rail airbags are designed to
help reduce the risk of full or partial ejection in rollover
events, although no system can prevent all such
ejections.
But airbags would not help in many types of collisions,
primarily because the occupant’s motion is not
toward those airbags. SeeWhen Should an Airbag
Inflate? on page 1-73for more information.
Airbags should never be regarded as anything more
than a supplement to safety belts.
What Will You See After an Airbag
Inates?
After the frontal airbags inate, they quickly deate, so
quickly that some people may not even realize an
airbag inated. Roof-rail airbags may still be at least
partially inated for some time after they deploy. Some
components of the airbag module may be hot for
several minutes. For location of the airbag modules, see
What Makes an Airbag Inflate? on page 1-74.
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
deated airbags. Airbag ination does not preventthe driver from seeing out of the windshield or being
able to steer the vehicle, nor does it prevent people from
leaving the vehicle.
{CAUTION:
When an airbag inates, 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 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
inates, 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.
Your vehicle has a feature that may automatically
unlock the doors, turn the interior lamps on, and turn
the hazard warning ashers on when the airbags inate.
You can lock the doors, turn the interior lamps off,
and turn the hazard warning ashers off by using the
controls for those features.
1-75

Adding Equipment to Your
Airbag-Equipped Vehicle
Q:Is there anything I might add to or change
about the vehicle that could keep the airbags
from working properly?
A:Yes. If you add things that change your vehicle’s
frame, bumper system, height, front end or side
sheet metal, they may keep the airbag system from
working properly. Changing or moving any parts
of the front seats, safety belts, the airbag sensing
and diagnostic module, steering wheel, instrument
panel, roof-rail airbag modules, ceiling headliner
or pillar garnish trim, overhead console, front
sensors, rollover sensor module, or airbag wiring
can affect the operation of the airbag system.
In addition, your vehicle may have a passenger
sensing system for the right front passenger’s
position, which includes sensors that are part of the
passenger’s seat. The passenger sensing system
may not operate properly if the original seattrim 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).
SeePassenger Sensing System on page 1-80.
If you have any questions about this, you should
contact Customer Assistance before you modify
your vehicle. The phone numbers and addresses for
Customer Assistance are in Step Two of the
Customer Satisfaction Procedure in this manual.
SeeCustomer Satisfaction Procedure on page 7-2.
If your vehicle has rollover roof-rail airbags, see
Different Size Tires and Wheels on page 5-86
for additional important information.
1-85