
Black plate (11,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-11
After operation in mud or sand,
have the brake linings cleaned and
checked. These substances can
cause glazing and uneven braking.
Check the body structure, steering,
suspension, wheels, tires, and
exhaust system for damage and
check the fuel lines and cooling
system for any leakage.
More frequent maintenance
service is required. Refer to the
Maintenance Schedule for more
information.
Driving on Wet Roads
Rain and wet roads can reduce
vehicle traction and affect your
ability to stop and accelerate.
Always drive slower in these types
of driving conditions and avoid
driving through large puddles and
deep‐standing or flowing water.
{WARNING
Wet brakes can cause crashes.
They might not work as well in a
quick stop and could cause
pulling to one side. You could
lose control of the vehicle.
After driving through a large
puddle of water or a car/vehicle
wash, lightly apply the brake
pedal until the brakes work
normally.
Flowing or rushing water creates
strong forces. Driving through
flowing water could cause the
vehicle to be carried away. If this
happens, you and other vehicle
occupants could drown. Do not
ignore police warnings and be
very cautious about trying to drive
through flowing water.
Hydroplaning
Hydroplaning is dangerous. Water
can build up under the vehicle's
tires so they actually ride on the
water. This can happen if the road
is wet enough and you are going
fast enough. When the vehicle is
hydroplaning, it has little or no
contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to
slow down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet
weather driving tips include:
.Allow extra following distance.
.Pass with caution.
.Keep windshield wiping
equipment in good shape.
.Keep the windshield washer fluid
reservoir filled.

Black plate (69,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-69
If the vehicle has the 6.2L V8 engine
(VIN Code 2), use premium
unleaded gasoline with a posted
octane rating of 91 or higher. You
can also use regular unleaded
gasoline rated at 87 octane or
higher, but the vehicle's acceleration
could be slightly reduced, and a
slight audible knocking noise,
commonly referred to as spark
knock, might be heard. If the octane
is less than 87, you might notice a
heavy knocking noise when you
drive. If this occurs, use a gasoline
rated at 87 octane or higher as soon
as possible. Otherwise, you could
damage the engine. If heavy
knocking is heard when using
gasoline rated at 87 octane or
higher, the engine needs service.Gasoline Specifications
(U.S. and Canada Only)
At a minimum, gasoline should
meet ASTM specification D 4814
in the United States or
CAN/CGSB‐3.5 or 3.511 in
Canada. Some gasolines contain
an octane-enhancing additive called
methylcyclopentadienyl manganese
tricarbonyl (MMT). We recommend
against the use of gasolines
containing MMT. SeeFuel Additives
on page 9‑70 for additional
information.
California Fuel
Requirements
If the vehicle is certified to meet
California Emissions Standards, it is
designed to operate on fuels that
meet California specifications. See
the underhood emission control
label. If this fuel is not available in
states adopting California Emissions
Standards, the vehicle will operate
satisfactorily on fuels meeting
federal specifications, but emission control system performance might
be affected. The malfunction
indicator lamp could turn on and the
vehicle might fail a smog‐check test.
See
Malfunction Indicator Lamp on
page 5‑22. If this occurs, return to
your authorized dealer for diagnosis.
If it is determined that the condition
is caused by the type of fuel used,
repairs might not be covered by the
vehicle warranty.
Fuels in Foreign
Countries
Never use leaded gasoline or any
other fuel not recommended in the
previous text on fuel. Costly repairs
caused by use of improper fuel
would not be covered by the vehicle
warranty.
To check the fuel availability, ask an
auto club, or contact a major oil
company that does business in the
country where you will be driving.

Black plate (73,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-73
The TIGHTEN GAS CAP message
displays on the Driver Information
Center (DIC) if the fuel cap is not
properly installed. SeeFuel System
Messages on page 5‑43 for more
information.
{WARNING
If a fire starts while you are
refueling, do not remove the
nozzle. Shut off the flow of fuel
by shutting off the pump or by
notifying the station attendant.
Leave the area immediately.
Notice: If a new fuel cap is
needed, be sure to get the right
type of cap from your dealer. The
wrong type of fuel cap might not
fit properly, might cause the
malfunction indicator lamp to
light, and could damage the fuel
tank and emissions system. See
Malfunction Indicator Lamp on
page 5‑22.
Filling a Portable Fuel
Container
{WARNING
Never fill a portable fuel container
while it is in the vehicle. Static
electricity discharge from the
container can ignite the fuel
vapor. You can be badly burned
and the vehicle damaged if this
occurs. To help avoid injury to you
and others:
.Dispense fuel only into
approved containers.
.Do not fill a container while it
is inside a vehicle, in a
vehicle's trunk, pickup bed,
or on any surface other than
the ground.
(Continued)
WARNING (Continued)
.Bring the fill nozzle in contact
with the inside of the fill
opening before operating the
nozzle. Contact should be
maintained until the filling is
complete.
.Do not smoke while
pumping fuel.
.Do not use a cellular phone
while pumping fuel.

Black plate (37,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-37
3. Install the new blade onto thearm connector and make sure
the grooved areas are fully set in
the locked position.
For the proper type and size, see
Maintenance Replacement Parts on
page 11‑15.
Glass Replacement
If the windshield or front side
glass must be replaced, see your
dealer to determine the correct
replacement glass.
Headlamp Aiming
The vehicle has a visual optical
headlamp aiming system. The aim
of the headlamps has been preset
at the factory and should need no
further adjustment.
However, if the vehicle is damaged
in a crash, the aim of the headlamps
may be affected and adjustment
may be necessary.
If oncoming vehicles flash their high
beams at you, this may mean the
vertical aim of the headlamps needs
to be adjusted.
It is recommended that the vehicle
be taken to the dealer for service if
the headlamps need to be adjusted.
It is possible, however, to re-aim the
headlamps as described. The vehicle should:.Be placed so the headlamps
are 7.6 m (25 ft) from a
light‐colored wall.
.Have all four tires on a level
surface which is level all the way
to the wall.
.Be placed so it is perpendicular
to the wall.
.Not have any snow, ice, or mud
on it.
.Be fully assembled and all other
work stopped while headlamp
aiming is being performed.
.Be loaded with a full tank of
fuel and one person or 75 kg
(160 lbs) sitting on the
driver seat.
.Have the tires properly inflated.
.Have the spare tire in its proper
location in the vehicle.

Black plate (8,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
13-8 Customer Information
Roadside Assistance is not a part of
the New Vehicle Limited Warranty.
GMC and General Motors of
Canada Limited reserve the right to
make any changes or discontinue
the Roadside Assistance program at
any time without notification.
GMC and General Motors of
Canada Limited reserve the right to
limit services or payment to an
owner or driver if they decide the
claims are made too often, or the
same type of claim is made many
times.
Services Provided
.Emergency Fuel Delivery:
Delivery of enough fuel for the
vehicle to get to the nearest
service station.
.Lock‐Out Service:Service to
unlock the vehicle if you are
locked out. A remote unlock
may be available if you have
OnStar
®. For security reasons,
the driver must present
identification before this service
is given.
.Emergency Tow From a Public
Road or Highway: Tow to the
nearest GMC dealer for warranty
service, or if the vehicle was in
a crash and cannot be driven.
Assistance is also given when
the vehicle is stuck in the sand,
mud, or snow.
.Flat Tire Change: Service to
change a flat tire with the spare
tire. The spare tire, if equipped,
must be in good condition and
properly inflated. It is the owner's
responsibility for the repair or
replacement of the tire if it is not
covered by the warranty.
.Battery Jump Start: Service to
jump start a dead battery.
.Trip Routing Service: Detailed
maps of North America when
requested either with the
most direct route or the most
scenic route. Additional travel
information is also available.
Allow three weeks for delivery.
.Trip Interruption Benefits and
Assistance: If your trip is
interrupted due to a warranty
failure, incidental expenses
may be reimbursed during the
5 years/(160 000 km) 100,000 mi
Powertrain warranty period.
Items considered are hotel,
meals, and rental car.
Services Not Included in
Roadside Assistance
.Impound towing caused by
violation of any laws.
.Legal fines.
.Mounting, dismounting,
or changing of snow tires,
chains, or other traction devices.
.Towing or services for vehicles
driven on a non-public road or
highway.

Black plate (19,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Customer Information 13-19
Vehicle Data
Recording and
Privacy
This GM vehicle has a number of
sophisticated computers that record
information about the vehicle’s
performance and how it is driven.
For example, the vehicle uses
computer modules to monitor and
control engine and transmission
performance, to monitor the
conditions for airbag deployment
and deploy airbags in a crash, and,
if so equipped, to provide antilock
braking to help the driver control the
vehicle. These modules may store
data to help your dealer technician
service the vehicle. Some modules
may also store data about how you
operate the vehicle, such as rate of
fuel consumption or average speed.
These modules may also retain the
owner’s personal preferences, such
as radio presets, seat positions, and
temperature settings.
Event Data Recorders
This vehicle has an Event Data
Recorder (EDR). The main purpose
of an EDR is to record, in certain
crash or near crash-like situations,
such as an airbag deployment or
hitting a road obstacle, data that
will assist in understanding how a
vehicle's systems performed. The
EDR is designed to record data
related to vehicle dynamics and
safety systems for a short period of
time, typically 30 seconds or less.
The EDR in this vehicle is designed
to record such data as:
.How various systems in the
vehicle were operating.
.Whether or not the driver and
passenger safety belts were
buckled/fastened.
.How far, if at all, the driver was
pressing the accelerator and/or
brake pedal.
.How fast the vehicle was
traveling. This data can help provide a better
understanding of the circumstances
in which crashes and injuries occur.
Important:
EDR data is recorded
by the vehicle only if a non-trivial
crash situation occurs; no data is
recorded by the EDR under normal
driving conditions and no personal
data (e.g., name, gender, age,
and crash location) is recorded.
However, other parties, such as
law enforcement, could combine
the EDR data with the type of
personally identifying data
routinely acquired during a crash
investigation.
To read data recorded by an EDR,
special equipment is required, and
access to the vehicle or the EDR is
needed. In addition to the vehicle
manufacturer, other parties, such
as law enforcement, that have the
special equipment, can read the
information if they have access to
the vehicle or the EDR.