2008 CHEVROLET SILVERADO Owners Manual

Tow/Haul Mode (Allison Transmission®
or Hydra-Matic®6-Speed Automatic
Transmission)
If your vehicle has an Allison or Hydra-Matic®6-speed
automatic transmission®, it has a tow/haul mode.
The tow/haul mode adjusts the transmission shift pattern
to reduce shift cycling, providing increased performance,
vehicle control, and transmission cooling when towing
or hauling heavy loads.
Turn the tow/haul mode on and off by pressing the
button, located on the end of the shift lever. When the
tow/haul is on, a light on the instrument panel cluster will
come on.
SeeTow/Haul Mode Light on page 3-54for more
information.
Also see “Tow Haul Mode” underTowing a Trailer on
page 4-55for more information.
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Grade Braking (Allison Transmission®
or Hydra-Matic®6-Speed Automatic
Transmission)
The Grade Braking shift modes can be activated by
pressing the button on the end of the shift control lever.
While in Range Selection Mode, Grade Braking is
deactivated allowing the driver to select a desired
range of gears.
Grade Braking is only active while the Tow/Haul Mode is
selected and you are not in the Range Selection Mode.
See “Tow/Haul Mode listed previously andAutomatic
Transmission Operation on page 2-28for more
information on the Range Selection Mode. 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.
See the diesel supplement for information on Cruise
Grade Braking.
Also seeTowing a Trailer on page 4-55for more
information.
Four-Wheel Drive
If your vehicle has Four-Wheel Drive, you can send the
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.
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.
While driving on clean dry pavement and during tight
turns, you may experience vibration in the steering
system.
Front Axle
The front axle engages and disengages automatically
when you shift the transfer case. Some delay for
the axle to engage or disengage is normal.
2-36

Manual Transfer Case
The transfer case shift lever is on the oor to the right
of the driver. Use this lever to shift into and out of
Four-Wheel Drive.A Four-Wheel Drive
indicator light comes
on when you shift into
four-wheel drive and the
front axle engages. See
Four-Wheel-Drive Light
on page 3-54.
Some delay between shifting and when the indicator
light comes on is normal.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeRecreational Vehicle Towing on page 4-50
Towing Your Vehicle on page 4-50
Notice:Driving on clean, dry pavement in
four-wheel drive for an extended period of time can
cause premature wear on your vehicle’s powertrain.
Do not drive on clean, dry pavement in Four-Wheel
Drive for extended periods of time.
2-37

4n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra torque.
You may never need Four-Wheel-Drive Low. It sends
maximum power to all four wheels. You might choose
Four-Wheel-Drive 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-Drive High. The transmission
gear shift feel is exaggerated.
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 in 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 2-50.
N (NEUTRAL):Shift to this setting only when your
vehicle needs to be towed. SeeRecreational Vehicle
Towing on page 4-50orTowing Your Vehicle on
page 4-50.
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.
2-38

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.
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 Four-Wheel High or Four-Wheel-Drive Low
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 the transfer case harder to shift and run
noisier.
If the transfer case shifter is in the NEUTRAL
position and you have difficulty reaching the
selected transfer case mode, with the engine
running, shift the transmission momentarily to
drive and then back to NEUTRAL. This will realign
the gear teeth in the transfer case and allow
you to complete the shift.
Shifting from Two-Wheel-Drive High to
Four-Wheel-Drive High

Shifts between Two-Wheel-Drive High and
Four-Wheel-Drive High can be made at any
vehicle speed.
Shift the transfer case lever in one continuous
motion into either the Four-Wheel-Drive High
or Two-Wheel-Drive High position.
In extremely cold weather, it may be necessary to
slow or stop the vehicle to shift into Four-wheel-Drive
High until your vehicle has warmed up.
While in Four-Wheel-Drive High, your vehicle can be
driven at any posted legal speed limit.
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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 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-Drive Low while the vehicle is moving
faster than 3 mph (5 km/h).
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 NEUTRAL (N).
{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 2-50.
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 will
end up in NEUTRAL. This is normal, and is a function
of the gear teeth aligning in your transfer case. When
this happens, make sure the engine is on, shift your
transmission momentarily to drive and back to
NEUTRAL, and then complete the 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.
2-40

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.
Electronic Transfer Case
The transfer case knob
is located next to the
steering column.
Use the dial to shift into and out of four-wheel drive.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeRecreational Vehicle Towing on page 4-50
Towing Your Vehicle on page 4-50
You can choose among four driving settings:
Indicator lights in the dial show which setting you are in.
The indicator lights will come on briey 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 ashes while shifting the
transfer case and remains illuminated 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.
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.
2-41

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 your 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.
StabiliTrak
®will not engage in this mode.
{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 2-50.N (NEUTRAL):Shift the vehicle’s transfer case
to NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-50orTowing
Your Vehicle on page 4-50for more information.
If the SERVICE 4–Wheel Drive message stays on, you
should take your vehicle to your dealer for service.
See “Service 4–Wheel Drive message” underDIC
Warnings and Messages on page 3-66.
Shifting Into Two-Wheel-Drive High
Turn the knob to the Two-Wheel-Drive High position.
This can be done at any speed, except when shifting
from Four-Wheel-Drive Low. See Shifting Out of
Four-Wheel-Drive Low for more information.
2-42