warning light GMC SIERRA 1500 2012 Owner's Guide

Black plate (46,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-46 Instruments and Controls
Several conditions may cause this
message to appear. SeeTire
Pressure Monitor Operation on
page 10‑62 for more information.
If the warning comes on and stays
on, there may be a problem with the
TPMS. See your dealer.
TIRE LEARNING ACTIVE
If the vehicle has the Tire Pressure
Monitor System (TPMS), this
message displays when the system
is re-learning the tire positions on
your vehicle. The tire positions must
be re-learned after rotating the tires
or after replacing a tire or sensor.
See Tire Inspection on page 10‑65,
Tire Rotation on page 10‑65, Tire
Pressure Monitor System on
page 10‑60, and Tire Pressure on
page 10‑58 for more information.
TIRE LOW ADD AIR TO TIRE
If the vehicle has the Tire Pressure
Monitor System (TPMS), this
message displays when the
pressure in one or more of the
vehicle's tires is low. This message also displays LEFT FRT (left front),
RIGHT FRT (right front), LEFT RR
(left rear), or RIGHT RR (right rear)
to indicate the location of the low
tire. The low tire pressure warning
light will also come on. See
Tire
Pressure Light on page 5‑27. You
can receive more than one tire
pressure message at a time. To
read the other messages that may
have been sent at the same time,
press the set/reset button or the
trip odometer reset stem. If a tire
pressure message appears on the
DIC, stop as soon as you can. Have
the tire pressures checked and set
to those shown on the Tire Loading
Information label. See Tires on
page 10‑50, Vehicle Load Limits on
page 9‑16, and Tire Pressure on
page 10‑58. The DIC also shows
the tire pressure values. See Driver
Information Center (DIC) on
page 5‑30.
Transmission Messages
SERVICE 4 WHEEL DRIVE
If the vehicle has four-wheel
drive, this message may display
if a problem occurs with the
four-wheel-drive system. If this
message appears, stop as soon as
possible and turn off the vehicle.
Make sure the key is in the LOCK/
OFF position for at least one minute
and then restart the vehicle and
check for the message on the DIC
display. If the message is still
displayed or appears again
when you begin driving, the
four-wheel-drive system needs
service. See your dealer.

Black plate (1,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Lighting 6-1
Lighting
Exterior Lighting
Exterior Lamp Controls . . . . . . . . 6-1
Exterior Lamps OffReminder . . . . . . . . . . . . . . . . . . . . 6-2
Headlamp High/Low-Beam Changer . . . . . . . . . . . . . . . . . . . . . 6-3
Flash-to-Pass . . . . . . . . . . . . . . . . . 6-3
Daytime Running Lamps (DRL) . . . . . . . . . . . . . . . . 6-3
Automatic Headlamp System . . . . . . . . . . . . . . . . . . . . . . 6-4
Hazard Warning Flashers . . . . . 6-5
Turn and Lane-Change Signals . . . . . . . . . . . . . . . . . . . . . . 6-5
Fog Lamps . . . . . . . . . . . . . . . . . . . . 6-6
Auxiliary Roof-Mounted Lamp . . . . . . . . . 6-6
Interior Lighting
Instrument Panel IlluminationControl . . . . . . . . . . . . . . . . . . . . . . 6-7
Cargo Lamp . . . . . . . . . . . . . . . . . . 6-8
Dome Lamps . . . . . . . . . . . . . . . . . 6-8
Reading Lamps . . . . . . . . . . . . . . . 6-8
Lighting Features
Entry Lighting . . . . . . . . . . . . . . . . . 6-9
Exit Lighting . . . . . . . . . . . . . . . . . . . 6-9
Battery Load Management . . . . 6-9
Battery Power Protection . . . . 6-10
Exterior Lighting
Exterior Lamp Controls
The exterior lamps control is located
on the instrument panel to the left of
the steering wheel.
It controls the following systems:
.Headlamps
.Taillamps
.Parking Lamps
.License Plate Lamps
.Instrument Panel Lights
.Roof Marker Lamps
(If Equipped)

Black plate (5,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Lighting 6-5
If the vehicle is not equipped
with DIC buttons, exit lighting is
automatic. When it is dark enough
outside, the exterior lamps remain
on for 30 seconds after the ignition
is moved from ON/RUN to
LOCK/OFF.
For vehicles without a radio, the
instrument panel light remains on for
30 seconds with the driver door
closed. For vehicles with a radio,
the instrument panel light remains
on for 10 minutes with the driver
door closed. SeeRetained
Accessory Power (RAP) on
page 9‑29.
The regular headlamp system can
be turned on when needed.Hazard Warning Flashers
|(Hazard Warning Flashers):
Press this button located on top of
the steering column, to make the
front and rear turn signal lamps
flash on and off. This warns others
that you are having trouble. Press
again to turn the flashers off.
When the hazard warning flashers
are on, the vehicle's turn signals will
not work.
Turn and Lane-Change
Signals
An arrow on the instrument panel
cluster flashes in the direction of the
turn or lane change.
Move the lever all the way up or
down to signal a turn.
Raise or lower the lever for less
than one second until the arrow
starts to flash to signal a lane
change. This causes the turn
signals to automatically flash
three times. It will flash six times
if tow-haul mode is active.

Black plate (8,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-8 Driving and Operating
.Use headlamps even during the
day to make the vehicle more
visible.
{WARNING
Driving to the top of a hill at high
speed can cause an accident.
There could be a drop-off,
embankment, cliff, or even
another vehicle. You could be
seriously injured or killed. As you
near the top of a hill, slow down
and stay alert.
.Never go downhill forward
or backward with either the
transmission or transfer case in
N (Neutral). The brakes could
overheat and you could lose
control.
{WARNING
If the vehicle has the two‐speed
automatic transfer case, shifting
the transfer case to N (Neutral)
can cause your vehicle to roll
even if the transmission is in
P (Park). This is because the
N (Neutral) position on the
transfer case overrides the
transmission. You or someone
else could be injured. If leaving
the vehicle, set the parking brake
and shift the transmission to
P (Park). Shift the transfer case to
any position but N (Neutral).
.When driving down a hill, keep
the vehicle headed straight
down. Use a low gear because
the engine will work with the
brakes to slow the vehicle and
help keep the vehicle under
control.
{WARNING
Heavy braking when going down
a hill can cause your brakes to
overheat and fade. This could
cause loss of control and you or
others could be injured or killed.
Apply the brakes lightly when
descending a hill and use a low
gear to keep vehicle speed under
control.
If the vehicle stalls on a hill:
1. Apply the brakes to stop the vehicle, and then apply the
parking brake.
2. Shift into P (Park) for an automatic transmission
or 1 (First) for a manual
transmission and then restart
the engine.
.If driving uphill when the
vehicle stalls, shift to
R (Reverse), release the
parking brake, and back
straight down.

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 (15,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-15
If it takes some time for help to
arrive, now and then when you run
the engine, push the accelerator
pedal slightly so the engine runs
faster than the idle speed. This
keeps the battery charged to restart
the vehicle and to signal for help
with the headlamps. Do this as little
as possible to save fuel.
If the Vehicle Is Stuck
Slowly and cautiously spin the
wheels to free the vehicle when
stuck in sand, mud, ice, or snow.
See“Rocking Your Vehicle to Get It
Out” later in this section.
If the vehicle has a traction system,
it can often help to free a stuck
vehicle. Refer to the vehicle's
traction system in the Index. If stuck
too severely for the traction system
to free the vehicle, turn the traction
system off and use the rocking
method.
{WARNING
If the vehicle's tires spin at high
speed, they can explode, and you
or others could be injured. The
vehicle can overheat, causing an
engine compartment fire or other
damage. Spin the wheels as little
as possible and avoid going
above 56 km/h (35 mph).
For information about using tire
chains on the vehicle, see Tire
Chains on page 10‑74.
Rocking Your Vehicle to Get
It Out
Turn the steering wheel left and
right to clear the area around the
front wheels. For four-wheel-drive
vehicles, shift into Four‐Wheel High. For vehicles with StabiliTrak
®, turn
the traction control part of the
system off. Shift back and forth
between R (Reverse) and a forward
gear, spinning the wheels as little as
possible. To prevent transmission
wear, wait until the wheels stop
spinning before shifting gears.
Release the accelerator pedal while
shifting, and press lightly on the
accelerator pedal when the
transmission is in gear. Slowly
spinning the wheels in the forward
and reverse directions causes a
rocking motion that could free the
vehicle. If that does not get the
vehicle out after a few tries, it might
need to be towed out. Recovery
hooks can be used, if the vehicle
has them. If the vehicle does need
to be towed out, see Towing the
Vehicle on page 10‑93.

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 (35,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-35
Automatic
Transmission
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Vehicles with an automatic
transmission have an electronic
shift position indicator within the
instrument panel cluster. This
display comes on when the ignition
key is turned to the ON/RUN
position.
There are several different positions
for the shift lever.
Hydra-Matic®4-Speed Automatic
Transmission
Heavy Duty 6-Speed Automatic
Transmission Shown (Light Duty 6‐Speed Similar)
See “Range Selection Mode” under
Manual Mode on page 9‑38.
P (Park): This position locks the
rear wheels. It is the best position
to use when starting the engine
because the vehicle cannot move
easily. When parked on a hill,
especially when the vehicle has a
heavy load, you might notice an
increase in the effort to shift out of
P (Park). See “Torque Lock” under
Shifting Into Park on page 9‑30 for
more information.
{WARNING
It is dangerous to get out of the
vehicle if the shift lever is not fully
in P (Park) with the parking brake
firmly set. The vehicle can roll.
Do not leave the vehicle when
the engine is running unless
you have to. If you have left the
engine running, the vehicle can
move suddenly. You or others
could be injured. To be sure the
vehicle will not move, even when
you are on fairly level ground,
always set the parking brake and
move the shift lever to P (Park).
See Shifting Into Park on
page 9‑30. If you are pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9‑74.

Black plate (44,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-44 Driving and Operating
.Shifting from Two-Wheel Drive
High to Four-Wheel Drive High
while the vehicle is in motion
may require that moderate force
be applied to the shift lever for a
few seconds before Four-Wheel
Drive High can be engaged,
especially in cold weather.
.In extremely cold weather, it may
be necessary to slow or stop the
vehicle to shift into Four-Wheel
Drive High.
.While in Four-Wheel Drive High,
the vehicle can be driven at any
posted legal speed limit.
Shifting In or Out of Four-Wheel
Drive Low
Notice: Shifting the transfer
case into Four-Wheel-Drive Low
while moving at speeds faster
than 5 km/h (3 mph) may cause
premature wear to the transfer
case, and may cause the gears
to grind. To avoid causing
premature wear, and grinding the
gears, do not shift the transfer case into Four-Wheel-Drive Low
while the vehicle is moving faster
than 5 km/h (3 mph).
.Shifting into Four-Wheel Drive
Low should be done, if possible,
with the vehicle at a slight roll,
5 km/h (3 mph) or less.
.Shift the transmission into
N (Neutral).
{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). See
Parking Brake on
page 9‑54.
.Shifting into Four-Wheel Drive
Low with the vehicle at a stop
may be more difficult. You may
be unable to complete the shift
to Four-Wheel Drive Low, and the transfer case will end up in
N (Neutral). This is normal, and
is a function of the gear teeth
aligning in the transfer case.
When this happens, make
sure the engine is on, shift
the transmission momentarily
to D (Drive) and back to
N (Neutral), and then complete
the transfer case shift.
.Shift the transfer case shift lever
in one continuous motion into
the Four-Wheel Drive Low
position.
.When in Four-Wheel Drive
Low do not drive faster than
72 km/h (45 mph). This will
reduce wear and extend the life
of your transfer case.
Shifting In or Out of Neutral
1. With the vehicle running and the engine at an idle, set the parking
brake.
2. Place the transmission into N (Neutral).

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.