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Warning (Continued)
.There are holes or openings
in the vehicle body from
damage or aftermarket
modifications that are not
completely sealed.
If unusual fumes are detected or
if it is suspected that exhaust is
coming into the vehicle: . Drive it only with the
windows completely down.
. Have the vehicle repaired
immediately.
Never park the vehicle with the
engine running in an enclosed
area such as a garage or a
building that has no fresh air
ventilation.
Running the Vehicle
While Parked
It is better not to park with the
engine running.
If the vehicle is left with the engine
running, follow the proper steps to
be sure the vehicle will not move.
See Shifting Into Park 0283 and
Engine Exhaust 0285.
If parking on a hill and pulling a
trailer, see Driving Characteristics
and Towing Tips 0322.
Automatic
Transmission
If equipped, there is an electronic
shift lever position indicator within
the instrument 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.
Heavy-Duty 6-Speed Automatic
Transmission Shown, Others
Similar
See “Range Selection Mode” under
Manual Mode 0289.
P : 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
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effort to shift out of P (Park). See
“Torque Lock”underShifting Into
Park 0283.
{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. 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 0283 and
Driving Characteristics and
Towing Tips 0322.
{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 N (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
N (Neutral). See Shifting Into
Park 0283.
R : Use this gear to back up.
Caution
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 0268.
N : 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.
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288 Driving and Operating
Caution
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 : 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 55 km/h
(35 mph), push the accelerator
pedal about halfway down.
. Going about 55 km/h (35 mph) or
more, push the accelerator all
the way down.
By doing this, the vehicle shifts
down to the next gear and has
more power.
Use D (Drive) and Tow/Haul Mode
when towing a trailer, carrying a
heavy load, driving on steep hills, or driving off-road. 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 0260.
The vehicle has a shift stabilization
feature that adjusts the transmission
shifting to the current driving
conditions in order to reduce rapid
upshifts and downshifts. This shift
stabilization feature is designed to
determine, before making an
upshift, if the engine is able to
maintain vehicle speed by analyzing
things such as vehicle speed,
throttle position, and vehicle load.
If the shift stabilization feature
determines that a current vehicle
speed cannot be maintained, the
transmission does not upshift and
instead holds the current gear.
In some cases, this could appear to
be a delayed shift, however the
transmission is operating normally. The transmission uses adaptive
shift controls. The adaptive shift
control process continually
compares key shift parameters to
pre-programmed ideal shifts stored
in the transmission’s computer. The
transmission constantly makes
adjustments to improve vehicle
performance according to how the
vehicle is being used, such as with
a heavy load or when the
temperature changes. During this
adaptive shift control process,
shifting might feel different as the
transmission determines the best
settings.
When temperatures are very cold,
the transmission's gear shifting
could be delayed providing more
stable shifts until the engine warms
up. Shifts could be more noticeable
with a cold transmission. This
difference in shifting is normal.
M :
This position allows selection of
a range of gears appropriate for
current driving conditions.
If equipped, see “Range Selection
Mode” underManual Mode 0289.
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Caution
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.
Normal Mode Grade Braking
If equipped with a gasoline engine
and an automatic transmission,
Normal Mode Grade Braking is
enabled when the vehicle is started,
but is not enabled in Range
Selection Mode. It assists in
maintaining desired vehicle speeds
when driving on downhill grades by
using the engine and transmission
to slow the vehicle. The first time
the system engages for each
ignition key cycle, a DIC message
will be displayed. SeeTransmission
Messages 0160. To disable or enable Normal Mode
Grade Braking within the current
ignition key cycle, press and hold
the Tow/Haul button for
five seconds. When the button is
released, the requested mode
change is made. A DIC message
displays. See
Transmission
Messages 0160.
For other forms of grade braking,
see Tow/Haul Mode 0292 and
Cruise Control 0306.
Kickdown Mode
The accelerator pedal provides an
additional downshift after pressing
through the kickdown feature.
It requires extra pedal pressure near
the end of its travel to engage.
Manual Mode
Range Selection Mode
If equipped, Range Selection Mode
helps control the vehicle's
transmission and vehicle speed
while driving downhill or towing a
trailer by letting you select a desired
range of gears.
To use this feature:
1. Move the shift lever to M (Manual Mode).
2. Press the plus/minus buttons on the shift lever to select the
desired range of gears for
current driving conditions.
With an 8–speed automatic
transmission, hold the plus/minus
buttons on the shift lever to select
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6-Speed Automatic TransmissionGear before shifting from D
(Drive) to M (Manual Mode) 6th 5th 4th 3rd 2nd 1st
Range after shifting from D
(Drive) to M (Manual Mode) M4 M4 M3 M2 M2 M1
8-Speed Automatic Transmission Gear before
shifting from D
(Drive) to M
(Manual Mode) 8th 7th 6th 5th 4th 3rd 2nd 1st
Range after
shifting from
D (Drive) to
M (Manual Mode)
– Tow/Haul not
engaged M6 M6 M5 M4 M3 M3 M2 M1
Range after
shifting from
D (Drive) to
M (Manual Mode)
– Tow/Haul
engaged M6 M5 M4 M3 M3 M3 M2 M1 Grade Braking is not available when
Range Selection Mode is active.
See
Tow/Haul Mode 0292.
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.
Caution
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.
Low Traction Mode
If equipped, Low Traction Mode
assists in vehicle acceleration when
road conditions are slippery, such
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292 Driving and Operating
as with ice or snow. While the
vehicle is at a stop, select M2 using
Range Selection Mode. This will
limit torque to the wheels and help
to prevent the tires from spinning.
Tow/Haul Mode
Vehicles with an automatic
transmission have a Tow/Haul
Mode. The Tow/Haul Mode adjusts
the transmission shift pattern to
reduce shift cycling. This provides
increased performance, vehicle
control, and enhanced transmission
and engine cooling when drivingdown steep hills or mountain
grades, towing, or hauling heavy
loads.
The selector button is on the end of
the shift lever. Turn the Tow/Haul
Mode on and off by pressing the
button. When the Tow/Haul Mode is
enabled, a light on the instrument
cluster will come on.
See
Tow/Haul Mode Light 0144 and
Hill and Mountain Roads 0266.
Also see “Tow/Haul Mode” under
Towing Equipment 0339.
Tow/Haul Mode Grade Braking
Tow/Haul Mode Grade Braking is
only enabled while the Tow/Haul
Mode is selected and the vehicle is
not in the Range Selection Mode.
See “Tow/Haul Mode” listed
previously and Manual Mode0289.
Tow/Haul Mode Grade Braking
assists in maintaining desired
vehicle speeds when driving on
downhill grades by using the engine
and transmission to slow the
vehicle. On vehicles with a gasoline engine,
to disable or enable Tow/Haul
Grade Braking within the current
ignition key cycle, press and hold
the Tow/Haul button for
five seconds. When the button is
released, the requested mode
change is made. A DIC message is
displayed. See
Transmission
Messages 0160.
On vehicles with a diesel engine,
Tow/Haul Mode Grade Braking can
be enabled or disabled by pressing
the Tow/Haul Mode button. Use the
exhaust brake and Tow/Haul Mode
for maximum grade braking.
See Towing Equipment 0339.
For other forms of grade braking,
see Automatic Transmission 0286
and Cruise Control 0306.
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N (Neutral) :Use only when the
vehicle needs to be towed. See
Recreational Vehicle Towing 0439
or Towing the Vehicle 0439.
2
m(Two-Wheel Drive High) : Use
this setting for driving on most
streets and highways. The front axle
is not engaged. This setting
provides the best fuel economy.
4
n(Four-Wheel Drive Low) : This
setting also engages the front axle
and delivers extra torque. Choose 4
nif driving off-road in deep sand,
deep mud, or deep snow, and while
climbing or descending steep hills.
When engaged, keep vehicle speed
below 72 km/h (45 mph).
4
m(Four-Wheel Drive High) : Use
this setting when extra traction is
needed. The front axle engages and
helps when driving on snowy or icy
roads, when off-roading, or when
plowing snow. The vehicle can be shifted between
2
mand 4mwhile the vehicle is
moving. In extremely cold weather,
it may be necessary to stop or slow
the vehicle to shift into 4
m.
Using the Manual Transfer Case
. Use quick motions to shift into or
out of 4
nor N (Neutral).
. Shifting may be harder when the
vehicle is cold, but will return to
normal once warmed up.
. Four-wheel drive reduces fuel
economy.
Shifting from 2
mto 4m
. Shifts can be made at any
vehicle speed.
. Shift in one continuous motion.
. Shifting while the vehicle is in
motion may require that
moderate force be applied to the
shift lever before 4
mcan be
engaged, especially in cold
weather. .
In extremely cold weather, it may
be necessary to slow or stop the
vehicle to shift.
. While in 4
m, the vehicle can be
driven at any posted legal speed
limit.
Shifting In or Out of 4
n
Caution
Shifting the transfer case into 4n
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.
1. If possible, shift with the vehicle moving 5 km/h (3 mph)
or less.
2. Shift the transmission into N (Neutral).
3. Shift the transfer case shift lever in one continuous motion.
4. Shifting with the vehicle at a stop may be more difficult. It is
possible that the shift will not
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Driving and Operating 295
complete and the transfer case
will remain in N (Neutral). This
is normal. To complete the
shift, with the engine running,
shift the transmission to
D (Drive) and back to
N (Neutral), and reattempt the
transfer case shift.
Shifting In or Out of Neutral 1. Have the engine running.
2. Set the parking brake. Press and hold the brake pedal. See
Parking Brake 0301.
3. Place the transmission into N (Neutral).
4. Shift the transfer case lever in one continuous motion into or
out of N (Neutral).Electronic Transfer Case
Use the transfer case knob, next to
the steering wheel, to shift into and
out of four-wheel drive for extra
traction.
An indicator light on the knob shows
which setting the transfer case is in.
The N (Neutral) indicator is on the
face of the knob. If the light displays
momentarily when the ignition is in
ON/RUN, but does not stay on, the
knob may have been turned while
the vehicle was off. To see the
indicator, turn the knob to another
position so that it matches the
actual transfer case setting. If no lights display, take the vehicle to
your dealer for service. An indicator
light flashes while shifting and until
the shift is complete.
If the transfer case cannot complete
a requested shift, it will return to the
last chosen setting. Turn the control
back to the previous setting to see
the indicator light.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
The settings are:
N (Neutral) : Use only when the
vehicle needs to be towed. See
Recreational Vehicle Towing 0439
or Towing the Vehicle 0439.
2
m(Two-Wheel Drive High) : Use
for driving on most streets and
highways. The front axle is not
engaged. This setting provides the
best fuel economy.