Six-Speed (VORTEC™ 8.1L V8 and
DURAMAX®6.6L V8 Engines)
Here is how to operate
your transmission.
This six-speed pattern is unique to GM manual
transmissions. The transmission always repositions the
shift lever to NEUTRAL, which is located between
FOURTH (4) and FIFTH (5) gear.
To prevent unintentional gear selections, additional
force is required to move the shift lever into
REVERSE (R) or FIRST (1). Use FIRST (1) when trailer
towing, driving with payload in the pickup box or
launching on a grade. Otherwise, start in SECOND (2)
gear. Only shift into FIRST (1) when the vehicle has
stopped moving.During the rst 500 miles (805 km) of vehicle use, start
the vehicle moving in FIRST (1) gear. This allows
the clutch components to wear-in properly.
FIRST (1):With the vehicle at a stop, release the
brake, press the clutch pedal and shift into FIRST (1).
Then, slowly let up on the clutch pedal as you press the
accelerator pedal. Only downshift into FIRST (1)
when the vehicle has come to a complete stop. If the
shift lever will not go into FIRST (1), put the lever
in NEUTRAL and let up on the clutch pedal to fully
engage the clutch. Press the clutch pedal again. Then,
shift into FIRST (1).
SECOND (2):With the vehicle at a stop, release the
brake, press the clutch pedal and shift into SECOND (2).
Then, slowly let up on the clutch pedal as you press
the accelerator pedal. With the vehicle moving, press the
clutch pedal and upshift into SECOND (2) from
FIRST (1) while applying light pressure to the right on
the shifter. Then, slowly let up on the clutch pedal
as you press the accelerator pedal. If you come to a
complete stop and the shift lever will not go into
SECOND (2), put the lever in NEUTRAL and let up on
the clutch pedal to fully engage the clutch. Press
the clutch pedal again. Then, shift into SECOND (2).
THIRD (3):Press the clutch pedal and upshift into
THIRD (3). Then, slowly let up on the clutch pedal as
you press the accelerator pedal.
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Up-Shift Light
If you have a manual
transmission, you may
have a shift light. This light
will show you when to
shift to the next higher gear
for best fuel economy.
When this light comes on, you can shift to the next
higher gear if weather, road and traffic conditions allow.
For the best fuel economy, accelerate slowly and
shift when the light comes on.
While you accelerate, it is normal for the light to go on
and off if you quickly change the position of the
accelerator.
If your vehicle has four-wheel drive and is equipped with
a manual transmission, disregard the shift light when
the transfer case is in Four-Wheel Low.
Ignore the shift light when you downshift.
Four-Wheel Drive
If your vehicle has four-wheel drive, you can send your
engine’s driving power to all four wheels for extra
traction. To get the most satisfaction out of four-wheel
drive, you must be familiar with its operation. Read
the part that follows before using four-wheel drive. See
the appropriate text for the transfer case in your
vehicle.
Front Axle Locking Feature
The front axle locks and unlocks automatically when
you shift the transfer case. Some delay for the axle to
lock or unlock is normal.
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An indicator light near the lever shows you the transfer
case settings:
Notice:Driving on clean, dry pavement in
four-wheel drive for an extended period of time may
cause premature wear on your vehicle’s powertrain.
Do not drive on clean, dry pavement in four-wheel
drive for extended periods of time.
4L (Four-Wheel Low):This setting also engages your
front axle and delivers extra torque. You may never
need 4L. It sends maximum power to all four wheels.
You might choose 4L if you are driving off-road in deep
sand, deep mud, deep snow, and while climbing or
descending steep hills. When operating in Four-Wheel
Low, the gear ratio provides additional torque when
compared to four-wheel high. The transmission
gear shift feel will be exaggerated.
{CAUTION:
Shifting the transfer case to NEUTRAL
can cause your vehicle to roll even if the
transmission is in PARK (P), or if you have a
manual transmission, even if you are in gear.
CAUTION: (Continued)
CAUTION: (Continued)
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 2-49.
N (Neutral):Shift to this setting only when your vehicle
needs to be towed. SeeRecreational Vehicle Towing
on page 4-62orTowing Your Vehicle on page 4-61.
2H (Two-Wheel High):This setting is used for driving
in most street and highway situations. Your front
axle is not engaged in two-wheel drive. This setting also
provides the best fuel economy.
4H (Four-Wheel 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
your front axle to help drive your vehicle. This is the best
setting to use when plowing snow.
You can shift from 2H to 4H or 4H high to 2H while the
vehicle is moving. Your front axle will engage faster
if you take your foot off of the accelerator for a couple
of seconds after you shift. In extremely cold weather, it
may be necessary to stop or slow the vehicle to
shift into four-wheel high.
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When Using the Manual Transfer Case
Shifting should be made using quick motions.
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 4H or 4L you may experience reduced fuel
economy.
Avoid driving in four-wheel drive on clean, dry
pavement. It may cause your tires to wear
faster, and make your transfer case harder to shift
and run noisier.
Shifting from 2H (Two-Wheel High) to
4H (Four-Wheel High)
Shifts between 2H and 4H can be made at any
vehicle speed.
It is easiest to shift the transfer case when
maintaining a constant speed or a slight
acceleration. If possible, avoid shifting while slowing
down, as it will may make it harder to shift.
Shift your transfer case lever in one continuous
motion into either the 4H or 2H position.
In extremely cold weather, it may be necessary to
slow or stop the vehicle to shift into four-wheel
high until your vehicle has warmed up.
While in 4H, your vehicle can be driven at any
posted legal speed limit.
Shifting In or Out of 4L (Four-Wheel Low)
Notice:Shifting the transfer case into 4L while
moving at speeds faster than 3 mph (5 km/h) 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 4L while the vehicle is
moving faster than 3 mph (5 km/h).
Shifts into 4L can be made with the vehicle at a stop, or
while slowly rolling about 1 to 3 mph (2 to 5 km/h).
Shift the automatic transmission into NEUTRAL (N),
or with a manual transmission, press the clutch
pedal, or shift into NEUTRAL (N).
Shift the transfer case shift lever in one continuous
motion into the 4L position.
When in 4L do not drive faster than 45 mph.
This will reduce wear and extend the life of
your transfer case.
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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 NEUTRAL (N).
Shift the transfer case in one continuous motion into or
out of the NEUTRAL position.
Automatic Transfer Case
The transfer case buttons
are located to the left of
the instrument panel
cluster.
Use these switches to shift into and out of four-wheel
drive.
Recommended Transfer Case Settings
Driving
ConditionsTransfer Case Settings
2
mAUTO
4WD4m4nN
Normal YES
Variable YES
Severe YES
Extreme YES
Vehicle
in Tow*YES
*SeeRecreational Vehicle Towing on page 4-62for
further information.
You can choose among four driving settings:
Notice:Driving on clean, dry pavement in
Four-Wheel-Drive High or Four-Wheel-Drive Low for
an extended period of time may cause premature
wear on your vehicle’s powertrain. Do not drive on
clean, dry pavement in Four-Wheel-Drive High or
Four-Wheel-Drive Low for extended periods of time.
AUTO 4WD (Automatic Four-Wheel Drive):This
setting is ideal for use when road surface traction
conditions are variable. When driving your vehicle in
Automatic Four-Wheel Drive, the front axle is engaged,
but the vehicle’s power is sent to the rear wheels.
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When the vehicle detects a loss of traction, the system
will automatically engage four-wheel drive. Driving in
this mode results in slightly lower fuel economy
than Two-Wheel High.
2
m(Two-Wheel High):This setting is used for driving
in most street and highway situations. Your front axle
is not engaged in two-wheel drive. This setting also
provides the best fuel economy.
{CAUTION:
Shifting the transfer case to NEUTRAL
can cause your vehicle to roll even if the
transmission is in PARK (P). 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 2-49.
N (NEUTRAL):Shift the vehicle’s transfer case to
N (NEUTRAL) only when towing your vehicle.
SeeRecreational Vehicle Towing on page 4-62or
Towing Your Vehicle on page 4-61for more information.4
m(Four-Wheel High):Use this setting when you
need extra traction, such a on snowy or icy roads or in
most off-road situations. This setting also engages
your front axle to help drive your vehicle. This is the best
setting to use when plowing snow.
4
n(Four-Wheel Low):This setting also engages
your front axle and delivers extra torque. You may never
need Four-Wheel Low. It sends maximum power to all
four wheels. You might choose Four-Wheel Low if
you are driving off-road in deep sand, deep mud, deep
snow, and while climbing or descending steep hills.
When operating in Four-Wheel Low, the gear ratio
provides additional torque when compared to
four-wheel high. The transmission gear shift feel will
be exaggerated.
Indicator lights in the switches show which setting your
transfer case is in. The indicator lights will come on
brie y when you turn on the ignition and one will stay on.
If the lights do not come on, you should take your
vehicle to your dealer for service. An indicator light will
ash while the transfer case is being shifted. It will
stay on when the shift is complete. If for some reason
the transfer case cannot make a requested shift, it
will return to the last chosen setting.
If the SERVICE 4WD message stays on, you should
take your vehicle to your dealer for service. See
DIC Warnings and Messages on page 3-54for further
information.
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Shifting into Four-Wheel High or AUTO
4WD (Automatic Four-Wheel Drive)
Press and release the four-wheel high or AUTO 4WD
switch. This can be done at any speed, except
when shifting from Four-Wheel Low, and the indicator
light will ash while shifting. It will remain on when
the shift is completed.
Shifting into Two-Wheel High
Press and release the Two-Wheel High switch. This can
be done at any speed, except when shifting from
Four-Wheel Low.
Shifting into Four-Wheel Low
Notice:Shifting the transfer case into Four-Wheel
Low while moving at speeds faster than 3 mph
(5 km/h) 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 Low while
the vehicle is moving faster than 3 mph (5 km/h).
To shift to Four-Wheel Low, the ignition must be in RUN
and the vehicle must be stopped or moving less than
3 mph (5 km/h) with the transmission in NEUTRAL (N).
The preferred method for shifting into Four-Wheel Low is
to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h).Press and release the Four-Wheel Low switch. You must
wait for the Four-Wheel Low indicator light to stop
ashing and remain on before shifting your transmission
in gear.
Notice:Shifting the transmission into gear before
the Four-Wheel Low indicator light has stopped
ashing could damage the transfer case. To
help avoid damaging your vehicle, always wait for
the Four-Wheel Low indicator light to stop ashing
before shifting the transmission into gear.
It is typical for your vehicle to exhibit signi cant
engagement noise and bump when shifting between
Four-Wheel Low and Four-Wheel High ranges or from
NEUTRAL (N) with the engine running.
If the Four-Wheel Low switch is pressed when your
vehicle is in gear and/or moving, the Four-Wheel Low
indicator light will ash for 30 seconds and not complete
the shift unless your vehicle is moving less than
3 mph (5 km/h) and the transmission is in NEUTRAL (N).
After 30 seconds the transfer case will shift to
four-wheel high mode.
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Shifting Out of Four-Wheel Low
To shift from Four-Wheel Low to Four-Wheel High,
AUTO 4WD, or Two-Wheel High, your vehicle must
be stopped or moving less than 3 mph (5 km/h) with
the transmission in NEUTRAL (N) and the ignition
in RUN. The preferred method for shifting out of
Four-Wheel Low is to have your vehicle moving
1 to 2 mph (1.6 to 3.2 km/h). Press and release the
Four-Wheel High, AUTO 4WD, or Two-Wheel High
switch. You must wait for the Four-Wheel High,
AUTO 4WD, or Two-Wheel High indicator light to
stop ashing and remain on before shifting your
transmission into gear.
Notice:Shifting the transmission into gear
before the Four-Wheel Low indicator light has
stopped ashing could damage the transfer case.
To help avoid damaging your vehicle, always
wait for the Four-Wheel Low indicator light to
stop ashing before shifting the transmission
into gear.
The transfer case may make noise and the vehicle
may jerk when the transfer case is shifted between
Four-Wheel Low and Four-Wheel High ranges or from
NEUTRAL with the engine running.If the four-wheel high, AUTO 4WD, or Two-Wheel
High switch is pressed when your vehicle is in gear
and/or moving, the Four-Wheel High, AUTO 4WD,
or Two-Wheel High indicator light will ash for
30 seconds but will not complete the shift unless your
vehicle is moving less than 3 mph (5 km/h) and the
transmission is in NEUTRAL (N).
Shifting Into NEUTRAL
{CAUTION:
Shifting the transfer case to NEUTRAL
can cause your vehicle to roll even if the
transmission is in PARK (P). 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 2-49.
To shift the transfer case to NEUTRAL do the following:
1. Make sure the vehicle is parked so that it will
not roll.
2. Set the parking brake.
3. Start the vehicle or turn the ignition to RUN.
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