service indicator GMC SIERRA 1500 2012 User Guide

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

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Instruments and Controls 5-29
information. When fuel is added this
light and message should go off. If it
does not, have the vehicle serviced
by your dealer.
Security Light
The security light should come on
briefly as the engine is started. If the
system is working normally, the
indicator light turns off. If it does not
come on, have the vehicle serviced
by your dealer.
If the light stays on and the engine
does not start, there could be a
problem with the theft-deterrent
system.This light is also used to indicate the
status of the anti-theft alarm system
when the ignition is turned off. The
light will flash rapidly if the alarm
system is arming and one or more
of the monitored entry points is not
closed. The light will stay on if the
alarm is arming and all entry points
are closed.
For information regarding this light
and the vehicle's security system,
see
Anti-theft Alarm System on
page 2‑11.High-Beam On Light
This light comes on when the
high-beam headlamps are in use.
See Headlamp High/Low-Beam
Changer on page 6‑3.
Front Fog Lamp Light
For vehicles with fog lamps, this
light comes on when the fog lamps
are on.
The light goes out when the fog
lamps are turned off. See Fog
Lamps on page 6‑6 for more
information.

Black plate (43,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Instruments and Controls 5-43
be reduced the next time the vehicle
is driven. The vehicle may be driven
at a reduced speed while this
message is on, but acceleration and
speed may be reduced. Anytime
this message stays on, the vehicle
should be taken to your dealer for
service as soon as possible.
Fuel System Messages
FUEL LEVEL LOW
This message displays and a chime
may sound if the fuel level is low.
Refuel as soon as possible. See
Fuel Gauge on page 5‑14andFuel
on page 9‑68 for more information.
TIGHTEN GAS CAP
This message may display along
with the check engine light on the
instrument panel cluster if the
vehicle's fuel cap is not tightened
properly. SeeMalfunction Indicator
Lamp on page 5‑22. Reinstall the
fuel cap fully. See Filling 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 this light and message off.
Key and Lock Messages
REPLACE BATTERY IN
REMOTE KEY
This message displays if a Remote
Keyless Entry (RKE) transmitter
battery is low. The battery needs to
be replaced in the transmitter. See
“Battery Replacement”
under
Remote Keyless Entry (RKE)
System Operation on page 2‑3.
Lamp Messages
TURN SIGNAL ON
This message displays and a chime
sounds if a turn signal is left on for
1.2 km (0.75 mi). Move the turn
signal/multifunction lever to the off
position.
Object Detection System
Messages
PARK ASST BLOCKED SEE
OWNERS MANUAL
This message displays if there is
something interfering with the park
assist system. See Ultrasonic
Parking Assist on page 9‑61 for
more information.
PARK ASSIST OFF
After the vehicle has been started,
this message displays to remind the
driver that the URPA system has
been turned off. Press the set/reset
button or the trip odometer reset
stem to acknowledge this message
and clear it from the DIC display. To
turn the URPA system back on, see
Ultrasonic Parking Assist on
page 9‑61.

Black plate (27,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-27
The steering can bind with the
wheels turned off center. If this
happens, move the steering wheel
from right to left while turning the
key to ACC/ACCESSORY. If this
does not work, then the vehicle
needs service.
Notice:Using a tool to force the
key to turn in the ignition could
cause damage to the switch or
break the key. Use the correct
key, make sure it is all the way in,
and turn it only with your hand.
If the key cannot be turned by
hand, see your dealer.
B (ACC/ACCESSORY): This
position lets things like the radio
and the windshield wipers operate
while the engine is off. Use this
position if the vehicle must be
pushed or towed.
C (ON/RUN): This position can
be used to operate the electrical
accessories and to display some
instrument panel cluster warning
and indicator lights. This position
can also be used for service and diagnostics, and to verify the
proper operation of the malfunction
indicator lamp as may be required
for emission inspection purposes.
The switch stays in this position
when the engine is running. The
transmission is also unlocked in this
position on automatic transmission
vehicles.
If you leave the key in the ACC/
ACCESSORY or ON/RUN position
with the engine off, the battery could
be drained. You may not be able to
start the vehicle if the battery is
allowed to drain for an extended
period of time.
D (START):
This is the position that
starts the engine. When the engine
starts, release the key. The ignition
switch returns to ON/RUN for
driving.
A warning tone will sound when
the driver door is opened and the
ignition is in ACC/ACCESSORY or
LOCK/OFF, and the key is in the
ignition.Starting the Engine
If the vehicle has a diesel engine,
see the Duramax® diesel
supplement for more information.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Notice: Do not try to shift to
P (Park) if the vehicle is moving.
If you do, you could damage the
transmission. Shift to P (Park)
only when the vehicle is stopped.
Move the shift lever to P (Park) or
N (Neutral). The engine will not start
in any other position. To restart the
engine when the vehicle is already
moving, use N (Neutral) only.
Notice: If you add electrical parts
or accessories, you could change
the way the engine operates. Any
resulting damage would not be
covered by the vehicle warranty.
See Add-On Electrical Equipment
on page 9‑105.

Black plate (45,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-45
Shift the transfer case in one
continuous motion into or out of the
N (Neutral) position.
Electronic Transfer Case
The transfer case knob is located
next to the steering column.
Use the dial to shift into and out of
four-wheel drive.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m 4m4n N
Normal YES Severe YES
Extreme YES
Vehicle in Tow* YES
*See Recreational Vehicle Towing on page 10‑93 orTowing the Vehicle on
page 10‑93.
You can choose among four driving
settings:
Indicator lights in the dial show
which setting you are in. The
indicator lights will come on briefly
when you turn on the ignition and
one will stay on. If the lights do not
come on, you should take the
vehicle to your dealer for service.
An indicator light flashes while
shifting the transfer case and
remains illuminated when the shift is complete. If for some reason the
transfer case cannot make a
requested shift, it will return to the
last chosen setting.
2
m(Two-Wheel Drive High):
This
setting is used for driving in most
street and highway situations.
The front axle is not engaged in
Two-Wheel Drive. This setting also
provides the best fuel economy.

Black plate (49,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-49
Automatic Transfer Case
The transfer case knob is located
next to the steering column.
Use the dial to shift into and out of
Four-Wheel Drive.
You can choose among five driving
settings:
Indicator lights in the dial show
which setting you are in. The
indicator lights will come on briefly
when you turn on the ignition andone will stay on. If the lights do
not come on, you should take the
vehicle to your dealer for service.
An indicator light will flash while
shifting the transfer case. It will
remain illuminated when the shift is
complete. If for some reason the
transfer case cannot make a
requested shift, it will return to the
last chosen setting.
2
m(Two-Wheel Drive High):
This
setting is used for driving in most
street and highway situations.
The front axle is not engaged in
Two-Wheel Drive. This setting also
provides the best fuel economy.
AUTO (Automatic Four-Wheel
Drive): This setting is ideal for
use when road surface traction
conditions are variable. When
driving the vehicle in AUTO, the
front axle is engaged, but the
vehicle's power is sent only to the front and rear wheels automatically
based on driving conditions. Driving
in this mode results in slightly lower
fuel economy than Two-Wheel
Drive High.
4
m(Four-Wheel Drive High):
Use
the Four-Wheel Drive High position
when extra traction is needed, such
as on snowy or icy roads or in most
off-road situations. This setting also
engages the front axle to help drive
the vehicle. This is the best setting
to use when plowing snow.
4
n(Four-Wheel Drive Low): This
setting also engages the front axle
and delivers extra torque. You may
never need this setting. It sends
maximum power to all four wheels.
You might choose Four-Wheel Drive
Low if you are driving off-road in
deep sand, deep mud, deep snow,
and while climbing or descending
steep hills.

Black plate (50,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-50 Driving and Operating
If the vehicle has StabiliTrak®,
shifting into Four-Wheel Drive Low
will turn Traction Control and
StabiliTrak off. See StabiliTrak
®
System on page 9‑55.
{WARNING
Shifting the transfer case to
N (Neutral) can cause the vehicle
to roll even if the transmission is
in P (Park). You or someone else
could be seriously injured. Be
sure to set the parking brake
before placing the transfer case in
N (Neutral). SeeParking Brake on
page 9‑54.
N (Neutral): Shift the vehicle's
transfer case to N (Neutral) only
when towing the vehicle. See
Recreational Vehicle Towing on
page 10‑93 orTowing the Vehicle
on page 10‑93 for more information. If the SERVICE 4 WHEEL DRIVE
message stays on, you should
take the vehicle to your dealer for
service. See
“SERVICE 4 WHEEL
DRIVE” underTransmission
Messages on page 5‑46.
Shifting Into Four-Wheel Drive
High or AUTO (Automatic
Four-Wheel Drive)
Turn the knob to the Four-Wheel
Drive High or AUTO position. This
can be done at any speed, except
when shifting from Four-Wheel
Drive Low. The indicator light will
flash while shifting. It will remain on
when the shift is completed.
Shifting Into Two-Wheel
Drive High
Turn the knob to the Two-Wheel
Drive High position. This can be
done at any speed, except when
shifting from Four-Wheel Drive Low.
The indicator light will flash while
shifting. It will remain on when the
shift is completed. Shifting Into Four-Wheel
Drive Low
When Four-Wheel Drive Low is
engaged, vehicle speed should
be kept below 72 km/h (45 mph).
Extended high-speed operation in
Four-Wheel Drive Low may damage
or shorten the life of the drivetrain.
To shift to the Four-Wheel Drive
Low position, the ignition must be in
ON/RUN and the vehicle must be
stopped or moving less than 5 km/h
(3 mph) with the transmission in
N (Neutral). The preferred method
for shifting into Four-Wheel Drive
Low is to have the vehicle moving
1.6 to 3.2 km/h (1 to 2 mph). Turn the
knob to the Four-Wheel Drive Low
position. You must wait for the
Four-Wheel Drive Low indicator
light to stop flashing and remain on
before shifting the transmission
into gear.

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 (70,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-70 Driving and Operating
Fuel Additives
To provide cleaner air, all gasolines
in the United States are now
required to contain additives that
help prevent engine and fuel system
deposits from forming, allowing the
emission control system to work
properly. In most cases, nothing
should have to be added to the fuel.
However, some gasolines contain
only the minimum amount of
additive required to meet U.S.
Environmental Protection Agency
regulations. To help keep fuel
injectors and intake valves clean
and avoid problems due to dirty
injectors or valves, look for gasoline
that is advertised as TOP TIER
Detergent Gasoline. Look for the
TOP TIER label on the fuel pump to
ensure gasoline meets enhanced
detergency standards developed by
the auto companies. A list of
marketers providing TOP TIER
Detergent Gasoline can be found at
www.toptiergas.com.For customers who do not use TOP
TIER Detergent Gasoline regularly,
one bottle of GM Fuel System
Treatment PLUS, added to the fuel
tank at every engine oil change,
can help clean deposits from fuel
injectors and intake valves. GM Fuel
System Treatment PLUS is the only
gasoline additive recommended by
General Motors. It is available at
your dealer.
Gasolines containing oxygenates,
such as ethers and ethanol, and
reformulated gasolines might be
available in your area. We
recommend that you use these
gasolines, if they comply with the
specifications described earlier.
However, E85 (85% ethanol) and
other fuels containing more than
15% ethanol must not be used in
vehicles that were not designed for
those fuels.
Notice:
This vehicle was not
designed for fuel that contains
methanol. Do not use fuel
containing methanol. It can
corrode metal parts in the fuel
system and also damage plastic
and rubber parts. That damage
would not be covered under the
vehicle warranty.
Some gasolines that are
not reformulated for low
emissions can contain an
octane-enhancing additive called
methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant
where you buy gasoline whether the
fuel contains MMT. We recommend
against the use of such gasolines.
Fuels containing MMT can reduce
spark plug life and affect emission
control system performance. The
malfunction indicator lamp might
turn on. If this occurs, return to your
dealer for service.

Black plate (71,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-71
Fuel E85 (85% Ethanol)
Vehicles that have a FlexFuel badge
and a yellow fuel cap can use either
unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85).
For all other vehicles, use only the
unleaded gasoline described under
Recommended Fuel on page 9‑68.
We encourage the use of E85 in
vehicles that are designed to use it.
The ethanol in E85 is a“renewable”
fuel, meaning it is made from
renewable sources such as corn
and other crops.
Many service stations will not
have an 85% ethanol fuel (E85)
pump available. The U.S.
Department of Energy has
an alternative fuels website
(www.afdc.energy.gov/afdc/locator/
stations/) that can help you find
E85 fuel. Those stations that do
have E85 should have a label
indicating ethanol content. Do not
use the fuel if the ethanol content is
greater than 85%. At a minimum, E85 should meet
ASTM Specification D 5798 or
CGSB Specification 3.512. Filling
the tank with fuel mixtures that
do not meet ASTM or CGSB
specifications can affect driveability
and could cause the malfunction
indicator lamp to come on. As the
outside temperature approaches
freezing, ethanol fuel distributors
should supply winter grade ethanol,
the same as with unleaded
gasoline.
It is best not to alternate repeatedly
between gasoline and E85. If you
do switch fuels, it is recommended
that you add as much fuel as
possible
—do not add less than
11 L (3 gal) when refueling. You
should drive the vehicle immediately
after refueling for at least 11 km
(7 mi) to allow the vehicle to
adapt to the change in ethanol
concentration. E85 has less energy per liter
(gallon) than gasoline, so you will
need to refill the fuel tank more
often when using E85 than when
you are using gasoline. See
Filling
the Tank on page 9‑72.
Notice: Some additives are not
compatible with E85 fuel and can
harm the vehicle's fuel system.
Do not add anything to E85.
Damage caused by additives
would not be covered by the
vehicle warranty.
Notice: This vehicle was not
designed for fuel that contains
methanol. Do not use fuel
containing methanol. It can
corrode metal parts in the fuel
system and also damage plastic
and rubber parts. That damage
would not be covered under the
vehicle warranty.