2012 GMC SIERRA 1500 warning

Black plate (42,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-42 Driving and Operating
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.
Notice: Driving on clean, dry
pavement in four-wheel drive for
an extended period of time can
cause premature wear on the
vehicle's powertrain. Do not
drive on clean, dry pavement in
Four-Wheel Drive for extended
periods of time. 4
n(Four-Wheel Drive Low):
This
setting also engages the front axle
and delivers extra torque. You may
never need Four-Wheel Drive Low.
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. 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.
A parking brake symbol is located
next to the N (Neutral) symbol as a
reminder to set the parking brake
before shifting the transfer case 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
(Continued)

Black plate (43,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-43
WARNING (Continued)
before placing the transfer case in
N (Neutral). SeeParking Brake on
page 9‑54.
N (Neutral): Shift to this setting
only when the vehicle needs to be
towed. See Recreational Vehicle
Towing on page 10‑93 orTowing the
Vehicle on page 10‑93.
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.
4
m(Four-Wheel Drive High): Use
this setting when you need extra
traction, such as on snowy or icy
roads or in most off-road situations.
This setting also engages the front
axle to help drive your vehicle. This
is the best setting to use when
plowing snow. You can shift from Two-Wheel
Drive High to Four-Wheel Drive
High or Four-Wheel Drive High to
Two-Wheel Drive High while the
vehicle is moving. In extremely cold
weather, it may be necessary to
stop or slow the vehicle to shift into
Four-Wheel Drive High.
When Using the Manual
Transfer Case
.Shifts into or out of Four-Wheel
Drive Low or N (Neutral) should
be made using quick motions to
avoid excessive gear grinding.
Shifting slowly may make it more
difficult to shift.
.You may notice that it is harder
to shift when the vehicle is cold.
After the vehicle warms up the
shifting will return to normal.
.While in Four-Wheel High or
Four-Wheel Drive Low you
may experience reduced fuel
economy.
.Avoid driving in Four-Wheel
Drive on clean, dry pavement.
It may cause your tires to wear
faster, make the transfer case
harder to shift, and run noisier.
.If the transfer case shifter is in
the N (Neutral) position and you
have difficulty reaching the
selected transfer case mode,
with the engine running, shift the
transmission momentarily to
D (Drive) and then back to
N (Neutral). This will realign the
gear teeth in the transfer case
and allow you to complete the
shift.
Shifting from Two-Wheel Drive
High to Four-Wheel Drive High
.Shifts between Two-Wheel Drive
High and Four-Wheel Drive High
can be made at any vehicle
speed.
.Shift the transfer case lever in
one continuous motion into
either the Four-Wheel Drive
High or Two-Wheel Drive High
position.

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 (46,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-46 Driving and Operating
4m(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 while driving off-road in deep
sand, deep mud, deep snow, and
while climbing or descending steep
hills.
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 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.
See
“Shifting Out of Four-Wheel
Drive Low” for more information.
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

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 (53,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-53
Brakes
Antilock Brake
System (ABS)
This vehicle has the Antilock
Brake System (ABS), an advanced
electronic braking system that helps
prevent a braking skid.
When the engine is started and the
vehicle begins to drive away, ABS
checks itself. A momentary motor or
clicking noise might be heard while
this test is going on, and it might
even be noticed that the brake
pedal moves a little. This is normal.
If there is a problem with ABS, this
warning light stays on. SeeAntilock
Brake System (ABS) Warning Light
on page 5‑26. If driving safely on a wet road and it
becomes necessary to slam on the
brakes and continue braking to
avoid a sudden obstacle, a
computer senses that the wheels
are slowing down. If one of the
wheels is about to stop rolling, the
computer will separately work the
brakes at each wheel.
ABS can change the brake pressure
to each wheel, as required, faster
than any driver could. This can help
the driver steer around the obstacle
while braking hard.
As the brakes are applied, the
computer keeps receiving updates
on wheel speed and controls
braking pressure accordingly.
Remember: ABS does not change
the time needed to get a foot up to
the brake pedal or always decrease
stopping distance. If you get too
close to the vehicle in front of you,
there will not be enough time to
apply the brakes if that vehicle
suddenly slows or stops. Always
leave enough room up ahead to
stop, even with ABS.
Using ABS
Do not pump the brakes. Just hold
the brake pedal down firmly and let
ABS work. You might hear the ABS
pump or motor operating and feel
the brake pedal pulsate, but this is
normal.
Braking in Emergencies
ABS allows the driver to steer and
brake at the same time. In many
emergencies, steering can help
more than even the very best
braking.

Black plate (54,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-54 Driving and Operating
Parking Brake
Set the parking brake by holding the
regular brake pedal down, then
pushing down the parking brake
pedal.
If the ignition is on, the brake
system warning light will come on.
SeeBrake System Warning Light on
page 5‑25.
Notice: Driving with the parking
brake on can overheat the brake
system and cause premature
wear or damage to brake system
parts. Make sure that the parking brake is fully released and the
brake warning light is off before
driving.
To release the parking brake, hold
the regular brake pedal down, then
push down momentarily on the
parking brake pedal until you feel
the pedal release. Slowly pull your
foot up off the parking brake pedal.
If the parking brake is not released
when you begin to drive, the brake
system warning light will flash and a
chime will sound warning you that
the parking brake is still on.
If you are towing a trailer and are
parking on a hill, see
Driving
Characteristics and Towing Tips on
page 9‑74.
Brake Assist
If this vehicle has StabiliTrak®, it
also has a Brake Assist feature
designed to assist the driver in
stopping or decreasing vehicle
speed in emergency driving
conditions. This feature uses the
stability system hydraulic brake control module to supplement the
power brake system under
conditions where the driver has
quickly and forcefully applied the
brake pedal in an attempt to quickly
stop or slow down the vehicle. The
stability system hydraulic brake
control module increases brake
pressure at each corner of the
vehicle until the ABS activates.
Minor brake pedal pulsation or
pedal movement during this time
is normal and the driver should
continue to apply the brake pedal
as the driving situation dictates
The Brake Assist feature will
automatically disengage when the
brake pedal is released or brake
pedal pressure is quickly
decreased.Hill Start Assist (HSA)
Non‐hybrid vehicles with StabiliTrak
have a Hill Start Assist (HSA)
feature, which may be useful when
the vehicle is stopped on a grade.

Black plate (57,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-57
It is recommended to leave the
system on for normal driving
conditions, but it may be necessary
to turn the system off if the vehicle
is stuck in sand, mud, ice or snow,
and you want to“rock”the vehicle to
attempt to free it. It may also be
necessary to turn off the system
when driving in extreme off-road
conditions where high wheel spin is
required. See If the Vehicle Is Stuck
on page 9‑15.
When the transfer case is in 4LO,
the stability system is automatically
disabled, the StabiliTrak light comes
on, and the appropriate message
will appear on the DIC. Both
traction control and StabiliTrak
are automatically disabled in this
condition.
Traction Control Operation
The TCS is part of the StabiliTrak
system. Traction control limits wheel
spin by reducing engine power
to the wheels (engine speed
management) and by applying brakes to each individual wheel
(brake-traction control) as
necessary.
The TCS is enabled automatically
when the vehicle is started. It will
activate and the StabiliTrak light
will flash if it senses that any of the
wheels are spinning or beginning to
lose traction while driving. If traction
control is turned off, only the
brake-traction control portion of
traction control will work. The
engine speed management will be
disabled. In this mode, engine
power is not reduced automatically
and the driven wheels can spin
more freely. This can cause the
brake-traction control to activate
constantly.
Notice:
If the wheel(s) of one axle
is allowed to spin excessively
while the StabiliTrak
®, ABS, brake
warning lights, and any relevant
DIC messages are displayed, the
transfer case could be damaged.
The repairs would not be covered
by the vehicle warranty. Reduce
engine power and do not spin the wheel(s) excessively while these
lights and messages are
displayed.
The TCS may activate on dry or
rough roads or under conditions
such as heavy acceleration while
turning or abrupt upshifts/downshifts
of the transmission. When this
happens, a reduction in acceleration
may be noticed, or a noise or
vibration may be heard. This is
normal.
If cruise control is being used when
the system activates, the StabiliTrak
light will flash and cruise control will
automatically disengage. Cruise
control may be reengaged when
road conditions allow. See
Cruise
Control on page 9‑58.
StabiliTrak may also turn off
automatically if it determines that a
problem exists with the system.
If the problem does not clear itself
after restarting the vehicle, see your
dealer for service.