2012 GMC SIERRA 1500 maintenance

Black plate (23,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Instruments and Controls 5-23
If the malfunction indicator lamp
comes on and stays on while the
engine is running, this indicates that
there is an OBD II problem and
service is required.
Malfunctions often are indicated by
the system before any problem is
apparent. Being aware of the light
can prevent more serious damage
to the vehicle. This system assists
the service technician in correctly
diagnosing any malfunction.
Notice:If the vehicle is
continually driven with this light
on, the emission controls might
not work as well, the vehicle fuel
economy might not be as good,
and the engine might not run as
smoothly. This could lead to
costly repairs that might not be
covered by the vehicle warranty. Notice:
Modifications made
to the engine, transmission,
exhaust, intake, or fuel system
of the vehicle or the replacement
of the original tires with other
than those of the same Tire
Performance Criteria (TPC) can
affect the vehicle's emission
controls and can cause this light
to come on. Modifications to
these systems could lead to
costly repairs not covered by
the vehicle warranty. This could
also result in a failure to pass a
required Emission Inspection/
Maintenance test. See
Accessories and Modifications on
page 10‑3.
This light comes on during a
malfunction in one of two ways:
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required. To prevent more serious damage to
the vehicle:
.Reduce vehicle speed.
.Avoid hard accelerations.
.Avoid steep uphill grades.
.If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Light On Steady: An emission
control system malfunction has
been detected on the vehicle.
Diagnosis and service might be
required.

Black plate (24,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-24 Instruments and Controls
The following may correct an
emission system malfunction:
.Check that the fuel cap is fully
installed. SeeFilling the Tank on
page 9‑72. The diagnostic
system can determine if the
fuel cap has been left off or
improperly installed. A loose or
missing fuel cap allows fuel to
evaporate into the atmosphere.
A few driving trips with the cap
properly installed should turn the
light off.
.Check that good quality fuel is
used. Poor fuel quality causes
the engine not to run as
efficiently as designed and may
cause stalling after start-up,
stalling when the vehicle is
changed into gear, misfiring,
hesitation on acceleration,
or stumbling on acceleration.
These conditions might go away
once the engine is warmed up. If one or more of these conditions
occurs, change the fuel brand used.
It will require at least one full tank of
the proper fuel to turn the light off.
See
Recommended Fuel on
page 9‑68.
If none of the above have made
the light turn off, your dealer can
check the vehicle. The dealer has
the proper test equipment and
diagnostic tools to fix any
mechanical or electrical problems
that might have developed.Emissions Inspection and
Maintenance Programs
Some local governments may have
programs to inspect the on-vehicle
emission control equipment. For
the inspection, the emission system
test equipment is connected
to the vehicle’s Data Link
Connector (DLC).
The DLC is under the instrument
panel to the left of the steering
wheel. See your dealer if assistance
is needed.
The vehicle may not pass
inspection if:
.The malfunction indicator lamp is
on with the engine running, or if
the light does not come on when
the ignition is turned to ON/RUN
while the engine is off. See
your dealer for assistance in
verifying proper operation of the
malfunction indicator lamp.
.The OBD II (On-Board
Diagnostics) system
determines that critical
emission control systems have
not been completely diagnosed.

Black plate (28,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-28 Instruments and Controls
When the Light Is On Steady
This indicates that one or more
of the tires are significantly
underinflated.
A Driver Information Center (DIC)
tire pressure message may also
display. SeeTire Messages on
page 5‑45. Stop as soon as
possible, and inflate the tires to the
pressure value shown on the Tire
and Loading Information label. See
Tire Pressure on page 10‑58.
When the Light Flashes First and
Then Is On Steady
If the light flashes for about a minute
and then stays on, there may be a
problem with the TPMS. If the
problem is not corrected, the light
will come on at every ignition
cycle. See Tire Pressure Monitor
Operation on page 10‑62.Engine Oil Pressure Light
Notice: Lack of proper engine oil
maintenance can damage the
engine. Driving with the engine
oil low can also damage the
engine. The repairs would not be
covered by the vehicle warranty.
Check the oil level as soon as
possible. Add oil if required,
but if the oil level is within the
operating range and the oil
pressure is still low, have the
vehicle serviced. Always follow
the maintenance schedule for
changing engine oil.
This light comes on briefly while
starting the engine. If it does not,
have the vehicle serviced by your
dealer. If the system is working
normally the indicator light then
goes off. If the light comes on and stays on, it
means that oil is not flowing through
the engine properly. The vehicle
could be low on oil and it might
have some other system problem.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Low Fuel Warning Light
This light, under the fuel gauge,
comes on briefly while the engine is
being started.
This light and a chime, if the vehicle
is equipped with a radio, comes on
when the fuel tank is low on fuel.
The Driver Information Center also
displays a FUEL LEVEL LOW
message. See
Fuel System
Messages on page 5‑43 for more

Black plate (34,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-34 Instruments and Controls
Vehicle Information Menu
Items (with DIC Buttons)
T(Vehicle Information):Press
this button to scroll through the
following menu items:
Oil Life
Press the vehicle information
button until OIL LIFE REMAINING
displays. This display shows an
estimate of the oil's remaining useful
life. If you see 99% OIL LIFE
REMAINING on the display, that
means 99% of the current oil life
remains. The engine oil life system
will alert you to change the oil on a
schedule consistent with your
driving conditions.
When the remaining oil life is low,
the CHANGE ENGINE OIL SOON
message will appear on the display.
See “CHANGE ENGINE OIL SOON”
under Engine Oil Messages on
page 5‑42. You should change the
oil as soon as you can. See Engine
Oil on page 10‑7. In addition to the
engine oil life system monitoring the
oil life, additional maintenance is recommended in the Maintenance
Schedule in this manual. See
Maintenance Schedule on
page 11‑3
for more information.
Remember, you must reset the OIL
LIFE display after each oil change.
It will not reset itself. Also, be
careful not to reset the OIL LIFE
display accidentally at any time
other than when the oil has just
been changed. It cannot be reset
accurately until the next oil change.
To reset the engine oil life system,
see Engine Oil Life System on
page 10‑10.
Units
Press the vehicle information button
until UNITS displays. This display
allows you to select between metric
or English units of measurement.
Once in this display, press the set/
reset button to select between
METRIC or ENGLISH units. All of
the vehicle information will then
be displayed in the unit of
measurement selected. Tire Pressure
If the vehicle has the Tire Pressure
Monitor System (TPMS), the
pressure for each tire can be viewed
in the DIC. The tire pressure will be
shown in either kilopascals (kPa) or
pounds per square inch (psi). Press
the vehicle information button
until the DIC displays FRONT
TIRES kPa (PSI) LEFT ##
RIGHT ##. Press the vehicle
information button again until the
DIC displays REAR TIRES kPa
(PSI) LEFT ## RIGHT ##.
If a low tire pressure condition is
detected by the system while
driving, a message advising you to
add pressure in a specific tire will
appear in the display. See
Tire
Pressure on page 10‑58 andTire
Messages on page 5‑45 for more
information.
If the tire pressure display shows
dashes instead of a value, there
may be a problem with the vehicle.
If this consistently occurs, see your
dealer for service.

Black plate (38,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-38 Instruments and Controls
Trailer Gain and Output
On vehicles with the Integrated
Trailer Brake Control (ITBC) system,
the trailer brake display appears in
the DIC. Press the trip odometer
reset stem until TRAILER GAIN and
OUTPUT display.
TRAILER GAIN shows the trailer
gain setting. This setting can be
adjusted from 0.0 to 10.0 with either
a trailer connected or disconnected.
OUTPUT shows the power output to
the trailer any time a trailer with
electric brakes is connected. Output
is displayed in 0 to 10 bars. Dashes
may appear in the OUTPUT display.
To adjust trailer gain see“Integrated
Trailer Brake Control System” under
Towing Equipment on page 9‑94 for
more information.
Speedometer
The speedometer shows how fast
the vehicle is moving in either
kilometers per hour (km/h) or miles
per hour (mph). The speedometer
cannot be reset. Battery
This display shows the current
battery voltage. If the voltage is in
the normal range, the value will
display. For example, the display
may read BATTERY 13 VOLTS.
Your vehicle's charging system
regulates voltage based on the state
of the battery. The battery voltage
may fluctuate when viewing this
information on the DIC. This is
normal.
Oil Pressure
This display shows the oil pressure
in either kilopascals (kPa) or pounds
per square inch (psi).
Compass Zone Setting
This display allows for setting the
compass zone. See
Compass on
page 5‑5 for more information.
Compass Recalibration
This display allows for calibrating
the compass. See Compass on
page 5‑5 for more information. Oil Life
To access this display, the vehicle
must be in P (Park). Press the trip
odometer reset stem until OIL LIFE
REMAINING displays. This display
shows an estimate of the oil's
remaining useful life. If you see
99% OIL LIFE REMAINING on the
display, that means 99% of the
current oil life remains. The engine
oil life system will alert you to
change the oil on a schedule
consistent with your driving
conditions.
When the remaining oil life is low,
the CHANGE ENGINE OIL SOON
message will appear on the display.
See
“CHANGE ENGINE OIL SOON”
under Engine Oil Messages on
page 5‑42. You should change the
oil as soon as you can. See Engine
Oil on page 10‑7. In addition to the
engine oil life system monitoring the
oil life, additional maintenance is
recommended in the Maintenance
Schedule in this manual. See
Maintenance Schedule on
page 11‑3 for more information.

Black plate (42,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-42 Instruments and Controls
SeeOverheated Engine Protection
Operating Mode on page 10‑24 for
information on driving to a safe
place in an emergency.
ENGINE OVERHEATED STOP
ENGINE
This message displays and a
chime may sound if the engine
cooling system reaches unsafe
temperatures for operation. Stop
and turn off the vehicle as soon as
it is safe to do so to avoid severe
damage. This message clears when
the engine has cooled to a safe
operating temperature.
Engine Oil Messages
CHANGE ENGINE OIL SOON
This message displays when the
engine oil needs to be changed.
When you change the engine oil, be
sure to reset the CHANGE ENGINE
OIL SOON message. See Engine
Oil Life System on page 10‑10 for
information on how to reset the
message. See Engine Oil on page 10‑7
andMaintenance
Schedule on page 11‑3 for more
information.
ENGINE OIL HOT IDLE
ENGINE
This message displays when the
engine oil becomes hotter than the
normal operating temperature. Stop
and allow the vehicle to idle until it
cools down. See Engine Coolant
Temperature Gauge on page 5‑16.
OIL PRESSURE LOW STOP
ENGINE
Notice: If you drive the vehicle
while the engine oil pressure is
low, severe engine damage may
occur. If a low oil pressure
warning appears on the Driver
Information Center (DIC), stop the
vehicle as soon as possible. Do
not drive the vehicle until the
cause of the low oil pressure is
corrected. See Engine Oil on
page 10‑7 for more information. This message displays if low oil
pressure levels occur. Stop the
vehicle as soon as safely possible
and do not operate it until the cause
of the low oil pressure has been
corrected. Check the oil as soon
as possible and have the vehicle
serviced by your dealer. See
Engine
Oil on page 10‑7.
Engine Power Messages
ENGINE POWER IS REDUCED
This message displays and a chime
may sound when the cooling system
temperature gets too hot and the
engine further enters the engine
coolant protection mode. See
Engine Overheating on page 10‑22
for more information.
This message also displays when
the vehicle's engine power is
reduced. Reduced engine power
can affect the vehicle's ability to
accelerate. If this message is
on, but there is no reduction in
performance, proceed to your
destination. The performance may

Black plate (4,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-4 Driving and Operating
Control of a Vehicle
Braking, steering, and accelerating
are important factors in helping to
control a vehicle while driving.
Braking
Braking action involves perception
time and reaction time. Deciding
to push the brake pedal is
perception time. Actually doing
it is reaction time.
Average driver reaction time is
about three-quarters of a second.
In that time, a vehicle moving at
100 km/h (60 mph) travels 20 m
(66 ft), which could be a lot of
distance in an emergency.
Helpful braking tips to keep in mind
include:
.Keep enough distance between
you and the vehicle in front
of you.
.Avoid needless heavy braking.
.Keep pace with traffic.If the engine ever stops while the
vehicle is being driven, brake
normally but do not pump the
brakes. Doing so could make the
pedal harder to push down. If the
engine stops, there will be some
power brake assist but it will be
used when the brake is applied.
Once the power assist is used up, it
can take longer to stop and the
brake pedal will be harder to push.
Steering
Hydraulic Power Steering
Your vehicle has hydraulic
power steering. It may require
maintenance. See Power Steering
Fluid
Power Steering Fluid on
page 10‑25.
If power steering assist is lost
because the engine stops or the
power steering system is not
functioning, the vehicle can be
steered but may required increased
effort. See your dealer if there is a
problem. If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Curve Tips
.Take curves at a reasonable
speed.
.Reduce speed before entering a
curve.
.Maintain a reasonable steady
speed through the curve
.Wait until the vehicle is out of
the curve before accelerating
gently into the straightaway.
Steering in Emergencies
.There are some situations when
steering around a problem may
be more effective than braking.
.Holding both sides of the
steering wheel allows you to turn
180 degrees without removing
a hand.
.Antilock Brake System (ABS)
allows steering while braking.

Black plate (6,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-6 Driving and Operating
.Try to avoid sudden steering,
acceleration, or braking,
including reducing vehicle speed
by shifting to a lower gear. Any
sudden changes could cause
the tires to slide.
Remember: Antilock brakes help
avoid only the braking skid.
Off-Road Driving
Four-wheel-drive vehicles can be
used for off-road driving. Vehicles
without four-wheel drive and
vehicles not equipped with All
Terrain (AT) or On-Off Road (OOR)
tires must not be driven off-road
except on a level, solid surface. To
contact the tire manufacturer for
more information about the original
equipment tires, see the Limited
Warranty and Owner Assistance
Information manual.
Controlling the vehicle is the key to
successful off-road driving. One of
the best ways to control the vehicle
is to control the speed.
{WARNING
When driving off-road, bouncing
and quick changes in direction
can easily throw you out of
position. This could cause you to
lose control and crash. You and
your passengers should always
wear safety belts.
Before Driving Off-Road
.Have all necessary maintenance
and service work completed.
.Fuel the vehicle, fill fluid levels,
and check inflation pressure in
all tires, including the spare,
if equipped.
.Read all the information about
four-wheel-drive vehicles in this
manual.
.Make sure all underbody
shields, if equipped, are properly
attached.
.Know the local laws that apply to
off-road driving. To gain more ground clearance if
needed, it may be necessary to
remove the front fascia lower
air dam.
Notice:
Operating the vehicle
for extended periods without
the front fascia lower air dam
installed can cause improper air
flow to the engine. Re‐attach the
front fascia air dam after off-road
driving.
Loading the Vehicle for
Off-Road Driving
{WARNING
.Unsecured cargo on the
load floor can be tossed
about when driving over
rough terrain. You or your
passengers can be struck by
flying objects. Secure the
cargo properly.
(Continued)