brake GMC SIERRA 2011 Service Manual

Black plate (39,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-39
Fast Idle System
If the vehicle has this feature it is
available only with cruise control.
The manual fast idle switch is
operated using the cruise control
buttons located on the left hand
side of the steering wheel.
This system can be used to
increase engine idle speed
whenever the following conditions
are met:
.The park brake is set.
.The brake pedal is not pressed.
.The vehicle must not be moving
and the accelerator must not be
pressed.To control the fast idle:
.To enable the Fast Idle System,
press and release the Cruise
Control On/Off button and
ensure that the switch LED is lit.
.Press and release the Cruise
Control Set switch. Engine
speed will be held at
approximately 1200 RPM.
When the fast idle is active the
Driver Information Center (DIC) will
display “FAST IDLE ON.”
One of the following actions will turn
off the fast idle:
.Pressing the brake.
.Selecting the Cruise Control
Cancel button.
.Releasing the Parking Brake.
.The transmission shifter is
moved out of P (Park) or
N (Neutral).
.Selecting the Cruise Control
On/Off button when it was
previously on.
.Pressing the Cruise Control Set
switch a second time.
.Pressing the accelerator greater
than a quarter of the down.
.Turning the ignition switch to the
LOCK/OFF position.

Black plate (41,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-41
WARNING (Continued)
You could be seriously injured.
Plug the cord into a properly
grounded three-prong 110-volt AC
outlet. If the cord will not reach,
use a heavy-duty three-prong
extension cord rated for at least
15 amps.
4. Before starting the engine, be sure to unplug and store the
cord as it was before to keep
it away from moving engine
parts. If you do not, it could
be damaged.
The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Shifting Into Park
{WARNING
It can be 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. 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, use the
steps that follow. With four-wheel
drive, if the transfer case is in
N (Neutral), the vehicle will be
free to roll, even if the shift lever
is in P (Park). So, be sure the
transfer case is in a drive
gear —not in N (Neutral). If you
are pulling a trailer, see Driving
Characteristics and Towing Tips
on page 9‑91. 1. Hold the brake pedal down, then
set the parking brake.
See Parking Brake on page 9‑69
for more information.
2. Move the shift lever into the P (Park) position by pulling
the shift lever toward you and
moving it up as far as it will go.
3. Be sure the transfer case is in a drive gear —not in N (Neutral).
4. Turn the ignition key to LOCK/OFF.
5. Remove the key and take it with you. If you can leave the vehicle
with the ignition key in your
hand, the vehicle is in P (Park).

Black plate (42,1)GMC Sierra Owner Manual - 2011
9-42 Driving and Operating
Leaving the Vehicle With the
Engine Running
{WARNING
It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear—not in
N (Neutral).
(Continued)
WARNING (Continued)
And, if you leave the vehicle
with the engine running, it could
overheat and even catch fire.
You or others could be injured.
Do not leave the vehicle with
the engine running unless you
have to.
If you have to leave the vehicle
with the engine running, be sure
your vehicle is in P (Park) and the
parking brake is firmly set before
you leave it. After you move the shift
lever into P (Park), hold the regular
brake pedal down. Then, see if you
can move the shift lever away from
P (Park) without first pulling it toward
you. If you can, it means that the
shift lever was not fully locked into
P (Park).
Torque Lock
If you are parking on a hill and
you do not shift your transmission
into P (Park) properly, the weight
of the vehicle may put too much
force on the parking pawl in the
transmission. You may find it difficult
to pull the shift lever out of P (Park).
This is called torque lock. To
prevent torque lock, set the parking
brake and then shift into P (Park)
properly before you leave the driver
seat. To find out how, Shifting Into
Park on page 9‑41.
When you are ready to drive, move
the shift lever out of P (Park) before
you release the parking brake.
If torque lock does occur, you may
need to have another vehicle push
yours a little uphill to take some of
the pressure from the parking pawl
in the transmission, then you will be
able to pull the shift lever out of
P (Park).

Black plate (43,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-43
Shifting Out of Park
This vehicle is equipped with
an electronic shift lock release
system. The shift lock release is
designed to:
.Prevent ignition key removal
unless the shift lever is in
P (Park) with the shift lever
button fully released.
.Prevent movement of the shift
lever out of P (Park), unless
the ignition is in ON/RUN or
ACC/ACCESSORY and the
regular brake pedal is applied.
The shift lock release is always
functional except in the case of an
uncharged or low voltage (less than
9 volt) battery.
If the vehicle has an uncharged
battery or a battery with low voltage,
try charging or jump starting the
battery. See Jump Starting on
page 10‑98 for more information. To shift out of P (Park) use the
following:
1. Apply the brake pedal.
2. Move the shift lever to the
desired position.
If you still are unable to shift out of
P (Park):
1. Ease the pressure on the shift lever.
2. While holding down the brake pedal, press the shift lever all
the way into P (Park).
3. Move the shift lever to the desired position.
If you are still having a problem
shifting, then have the vehicle
serviced soon.
Parking Over Things
That Burn
{WARNING
Things that can burn could touch
hot exhaust parts under the
vehicle and ignite. Do not park
over papers, leaves, dry grass,
or other things that can burn.

Black plate (45,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-45
Running the Vehicle
While Parked
It is better not to park with the
engine running. But if you ever have
to, here are some things to know.
{WARNING
Idling a vehicle in an enclosed
area with poor ventilation is
dangerous. Engine exhaust may
enter the vehicle. Engine exhaust
contains Carbon Monoxide (CO)
which cannot be seen or smelled.
It can cause unconsciousness
and even death. Never run the
engine in an enclosed area
that has no fresh air ventilation.
For more information, seeEngine
Exhaust on page 9‑44.
{WARNING
It can be dangerous to get out
of the vehicle if the automatic
transmission 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).
{WARNING
Four-wheel drive vehicles with the
transfer case in N (Neutral) will
allow the vehicle to roll, even if
the automatic transmission shift
lever is in P (Park). So, be sure
the transfer case is in a drive
gear —not in N (Neutral). Always
set the parking brake.
Follow the proper steps to be
sure the vehicle will not move.
See Shifting Into Park on
page 9‑41.
If pulling a trailer, see Driving
Characteristics and Towing Tips on
page 9‑91.

Black plate (46,1)GMC Sierra Owner Manual - 2011
9-46 Driving and Operating
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 9‑50. 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 9‑41 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
(Continued)

Black plate (47,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-47
WARNING (Continued)
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).
SeeShifting Into Park on
page 9‑41. If you are pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9‑91.
{WARNING
If you have Four-Wheel Drive, the
vehicle will be free to roll —even
if the shift lever is in P (Park) —if
the transfer case is in Neutral.
So, be sure the transfer case is
in a drive gear, Two-Wheel Drive
High or Four-Wheel Drive High or
Four-Wheel Drive Low —not in
Neutral. See Shifting Into Park
on page 9‑41. R (Reverse):
Use this gear to
back up.
Notice: Shifting to R (Reverse)
while the vehicle is moving
forward could damage the
transmission. The repairs would
not be covered by the vehicle
warranty. Shift to R (Reverse)
only after the vehicle is stopped.
To rock the vehicle back and forth to
get out of snow, ice, or sand without
damaging the transmission, see If
the Vehicle is Stuck on page 9‑23.
N (Neutral): In this position, the
engine does not connect with the
wheels. To restart when you are
already moving, use N (Neutral)
only. Also, use N (Neutral) when
the vehicle is being towed.
{WARNING
Shifting into a drive gear while the
engine is running at high speed is
dangerous. Unless your foot is
firmly on the brake pedal, the
vehicle could move very rapidly.
You could lose control and hit
people or objects. Do not shift
into a drive gear while the engine
is running at high speed.
Notice: Shifting out of P (Park)
or N (Neutral) with the engine
running at high speed may
damage the transmission.
The repairs would not be covered
by the vehicle warranty. Be sure
the engine is not running at high
speed when shifting the vehicle.

Black plate (49,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-49
M (Manual Mode):This position
is available on vehicles with the
Allison Transmission or Hydra-Matic
6-Speed transmission. It lets
drivers select the range of gears
appropriate for current driving
conditions. If the vehicle has this
feature, see “Range Selection
Mode” underManual Mode on
page 9‑50.
3 (Third): This position is also used
for normal driving. It reduces vehicle
speed more than D (Drive) without
using the brakes. You might choose
3 (Third) instead of D (Drive) when
driving on hilly, winding roads, when
towing a trailer, so there is less
shifting between gears and when
going down a steep hill.
2 (Second): This position reduces
vehicle speed even more than
3 (Third) without using the brakes.
You can use 2 (Second) on hills. It can help control vehicle speed as
you go down steep mountain roads,
but then you would also want to use
the brakes off and on.
If you manually select 2 (Second)
in an automatic transmission, the
transmission will start in second
gear. You can use this feature for
reducing the speed of the rear
wheels when you are trying to
start the vehicle from a stop on
slippery road surfaces.
1 (First):
For the Hydra-Matic
4-Speed transmission this position
reduces vehicle speed even more
than 2 (Second) without using the
brakes. You can use it on very steep
hills, or in deep snow or mud. If the
shift lever is put in 1 (First) while
the vehicle is moving forward, the
transmission does not shift into first
gear until the vehicle is going slowly
enough. For an Allison Transmission or
Hydra-Matic 6-Speed transmission,
this position reduces vehicle speed
without using the brakes. You can
use it for major/severe downgrades
and off-road driving where the
vehicle would otherwise accelerate
due to steepness of grade. When
you shift to 1 (First) it provides the
lowest gear appropriate to current
road speed and continues to
downshift as the vehicle slows,
eventually downshifting to
1 (First) gear.
Notice:
Spinning the tires or
holding the vehicle in one
place on a hill using only the
accelerator pedal may damage
the transmission. The repair will
not be covered by the vehicle
warranty. If you are stuck, do not
spin the tires. When stopping on
a hill, use the brakes to hold the
vehicle in place.

Black plate (50,1)GMC Sierra Owner Manual - 2011
9-50 Driving and Operating
Manual Mode
Range Selection Mode
(Allison®Transmission or
Hydra-Matic®6-Speed
Transmission)
The vehicle may have a Range
Selection Mode. The Range
Selection Mode helps control
the vehicle's transmission and
vehicle speed while driving down
hill or towing a trailer by letting you
select a desired range of gears. To use this feature, do the following:
1. Move the shift lever to
M (Manual Mode).
2. Press the plus/minus buttons, located on the steering column
shift lever, to select the desired
range of gears for current driving
conditions.
When M (Manual Mode) is selected
a number displays next to the M,
indicating the current gear.
This number is the highest gear
that can be used. However, the
vehicle can automatically shift to
lower gears as it adjusts to driving
conditions. This means that all
gears below that number are
available. When 5 (Fifth) is selected,
1 (First) through 5 (Fifth) gears are
automatically shifted by the vehicle,
but 6 (Sixth) cannot be used until
the plus/minus button located on
the steering column lever is used
to change to the gear. Grade Braking is not available when
Range Selection Mode is active.
See
Tow/Haul Mode on page 9‑51.
While using Range Selection Mode,
Cruise Control and the Tow/Haul
Mode can be used.
If the vehicle has an exhaust
brake, it can also be used, but will
not automatically downshift the
transmission. See Exhaust Brake in
the Duramax Diesel supplement.
Notice: Spinning the tires or
holding the vehicle in one
place on a hill using only the
accelerator pedal may damage
the transmission. The repair will
not be covered by the vehicle
warranty. If you are stuck, do not
spin the tires. When stopping on
a hill, use the brakes to hold the
vehicle in place.

Black plate (53,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-53
Grade Braking assists in
maintaining desired vehicle
speeds when driving on
downhill grades by automatically
implementing a shift schedule that
utilizes the engine and transmission
to slow the vehicle. This reduces
wear on the braking system and
increases control of the vehicle.
Grade Braking monitors vehicle
speed, acceleration, engine torque
and brake pedal usage. Using this
information, it detects when the
truck is on a downhill grade and
the driver desires to slow the
vehicle by pressing the brake.
This feature is active when
the exhaust brake is enabled
(if equipped).
Also seeTowing Equipment on
page 9‑112 for more information.Cruise Grade Braking
(Allison Transmission
or Hydra-Matic 6-Speed
Automatic Transmission)
Cruise Grade Braking assists
when driving on a downhill grade.
It maintains vehicle speed by
automatically implementing a shift
schedule that uses the engine
and the transmission to slow the
vehicle. Cruise Grade Braking
operates while Cruise Control is
engaged in Tow/Haul Mode to assist
in maintaining vehicle speed under
loaded vehicle conditions. It utilizes
vehicle acceleration and deviation
from desired speed to determine the correct gear for the operating
condition. If vehicle speed is above
the desired speed the transmission
will downshift to slow the vehicle.
If vehicle speed is near or below
desired speed the trans will upshift,
allowing vehicle speed to increase.
While in the Range Selection Mode,
Cruise Grade Braking is not
available.
This feature is active when
the exhaust brake is enabled
(if equipped).
See
“Range Selection Mode” under
Manual Mode on page 9‑50.