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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, the ignition is in ACC/ACCESSORY or LOCK/
OFF and the key is in the ignition.
Retained Accessory Power (RAP)
The following vehicle accessories can be used for up to
10 minutes after the engine is turned off:
.Audio System
.Power Windows
.OnStar®System (if equipped)
.Sunroof (if equipped)
These features work when the key is in ON/RUN or
ACC/ACCESSORY. Once the key is turned from ON/
RUN to LOCK/OFF, the windows and sunroof continue
to work up to 10 minutes until any door is opened. The
radio continues to work for up to 10 minutes or until the
driver door is opened.
Starting the Engine
If the vehicle has the DURAMAX®Diesel engine, see
the DURAMAX®Diesel manual for more information.
If the vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual 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.
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Starting Procedure
1. With your foot off the accelerator pedal, turn theignition key to START. When the engine starts, let
go of the key. The idle speed will go down as your
engine gets warm. Do not race the engine
immediately after starting it. Operate the engine
and transmission gently to allow the oil to warm up
and lubricate all moving parts.
The vehicle has a Computer-Controlled Cranking
System. This feature assists in starting the engine
and protects components. If the ignition key is
turned to the START position, and then released
when the engine begins cranking, the engine will
continue cranking for a few seconds or until the
vehicle starts. If the engine does not start and the
key is held in START for many seconds, cranking
will be stopped after 15 seconds to prevent
cranking motor damage. To prevent gear damage,
this system also prevents cranking if the engine is
already running. Engine cranking can be stopped
by turning the ignition switch to the ACC/
ACCESSORY or LOCK/OFF position.
Notice: Cranking the engine for long periods of
time, by returning the key to the START position
immediately after cranking has ended, can overheat
and damage the cranking motor, and drain the
battery. Wait at least 15 seconds between each try,
to let the cranking motor cool down. 2. If the engine does not start after 5‐10 seconds,
especially in very cold weather (below 0°F or
−18°C), it could be flooded with too much gasoline.
Try pushing the accelerator pedal all the way to the
floor and holding it there as you hold the key in
START for up to 15 seconds. Wait at least
15 seconds between each try, to allow the cranking
motor to cool down. When the engine starts, let go
of the key and accelerator. If the vehicle starts
briefly but then stops again, do the same thing.
This clears the extra gasoline from the engine. Do
not race the engine immediately after starting it.
Operate the engine and transmission gently until
the oil warms up and lubricates all moving parts.
Notice: The engine is designed to work with the
electronics in the vehicle. If you add electrical parts
or accessories, you could change the way the
engine operates. Before adding electrical
equipment, check with your dealer. If you do not,
the engine might not perform properly. Any
resulting damage would not be covered by the
vehicle warranty.
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Fast Idle System
Fast Idle System with Switch
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, press and release the
Cruise Control On/Off button and ensure that the
LED is lit.
.For the preset Fast Idle, press and release the
cruise set switch. This will set the preset fast idle
speed.
.For the variable fast idle, press and hold the
accelerator at the desired RPM, then press and
release the cruise control cruise set switch to set
the desired idle speed.
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 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.
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Adjustable Throttle and Brake Pedal
On vehicles with this feature, you can change the
position of the throttle and brake pedals.
No adjustment to the pedals can be made when the
vehicle is in R (Reverse) or while using the cruise
control.
The switch used to adjust
the pedals is located on
the instrument panel
below the climate control
system.
Press the arrow at the bottom of the switch to move the
pedals closer to your body. Press the arrow at the top of
the switch to move the pedals away from your body. Before you start driving, fully press the brake pedal to
confirm the adjustment is right for you. While driving,
make only small adjustments.
The vehicle may have a memory function which lets
pedal settings be saved and recalled. See
Memory
Seat, Mirrors, and Pedals
on page 2‑8for more
information.
Engine Coolant Heater
The engine heater can provide easier starting and
better fuel economy during engine warm-up in cold
weather conditions at or below −18°C (0°F). Vehicles
with an engine heater should be plugged in at least
four hours before starting. An internal thermostat
in the plug-end of the cord may exist which will prevent
engine coolant heater operation at temperatures
above −18°C (0°F).
If the vehicle has the DURAMAX
®Diesel engine, see
the DURAMAX®Diesel manual for more information.
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To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord. Thecord is secured to the Engine Compartment Fuse
Block with a clip. Carefully remove the wire tie
which bundles the electrical plug. Do not cut the
electrical cord.
3. Plug the cord into a normal, grounded 110-volt AC outlet.
{WARNING:
Plugging the cord into an ungrounded outlet could
cause an electrical shock. Also, the wrong kind of
extension cord could overheat and cause a fire.
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.
Active Fuel Management™
Vehicles with V8 engines may have Active Fuel
Management™. This system allows the engine to
operate on either all or half of its cylinders, depending
on the driving conditions.
When less power is required, such as cruising at a
constant vehicle speed, the system will operate in the
half cylinder mode, allowing the vehicle to achieve
better fuel economy. When greater power demands are
required, such as accelerating from a stop, passing,
or merging onto a freeway, the system will maintain
full-cylinder operation.
If the vehicle has an Active Fuel Management™
indicator, see
DIC Operation and Displays (With DIC
Buttons)
on page 4‑49or DIC Operation and Displays
(Without DIC Buttons)on page 4‑56for more
information on using this display.
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Automatic Transmission Operation
If the vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual 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” later in this section.
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 (Automatic Transmission)
under Shifting Into Park
on page 3‑51for more
information.
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{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). SeeShifting Into
Park
on page 3‑51. If you are pulling a trailer,
see Towing a Trailer on page 5‑51.
{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 3‑51.
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
Your Vehicle is Stuck in Sand, Mud, Ice, or Snow
on
page 5‑27.
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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. D (Drive):
This position is for normal driving. It provides
the best fuel economy. If you need more power for
passing, and you are:
.Going less than about 35 mph (55 km/h), push the
accelerator pedal about halfway down.
.Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
By doing this, the vehicle shifts down to the next
gear and has more power.
D (Drive) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road driving.
You might want to shift the transmission to a lower gear
selection if the transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding. See Skidding under
Loss of Control on page 5‑10.
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