
Ignition Positions
The ignition switch has
four different positions.
To shift out of P (Park), the ignition must be in ON/RUN
or ACC/ACCESSORY and the regular brake pedal must
be applied.
A (LOCK/OFF): This position locks the ignition. It also
locks the transmission on automatic transmission
vehicles. The key can be removed in LOCK/OFF.
On vehicles with an automatic transmission, the shift
lever must be in P (Park) to turn the ignition switch to
LOCK/OFF. 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
doesn't 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. 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.
3-22

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.
3-23

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.
3-27

{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.
3-29

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.
3-30

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 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 Neutral. SeeParking
Brake on page 3‑50. N (Neutral):
Shift to this setting only when the vehicle
needs to be towed. See Recreational Vehicle Towing
on
page 5‑44or Towing Your Vehicle on page 5‑44.
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.
3-38

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, 3 mph
(5 km/h) or less.
.Shift the transmission into N (Neutral).
{WARNING:
Shifting the transfer case to 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 Neutral. See Parking
Brake on page 3‑50.
.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 Four-Wheel-Drive Low do not drive faster
than 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).
Shift the transfer case in one continuous motion into or
out of the N (Neutral) position.
3-40

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 5‑6.
{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 3‑50.
N (Neutral): Shift the vehicle's transfer case to
N (Neutral) only when towing the vehicle. See
Recreational Vehicle Towing
on page 5‑44or Towing
Your Vehicleon page 5‑44for 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 message” underDIC
Warnings and Messages on page 4‑63.
3-42