2006 CHEVROLET SILVERADO automatic transmission

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
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 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.
2-41

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 signicant
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.
2-42

4m(Four-Wheel High):This setting engages your
front axle to help drive your vehicle. Use four-wheel high
when you need extra traction, such as on snowy or
icy roads, or in most off-road situations.
4
n(Four-Wheel Low):This setting also engages
your front axle to give you extra traction. You may never
need Four-Wheel Low. It sends the maximum power
to all four wheels. You might choose Four-Wheel Low if
you were driving off-road in sand, mud or 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 you which setting
you are in. The indicator lights will come on briey when
you turn on the ignition and the last chosen setting
will stay on. If the lights do not come on, you should take
your vehicle in for service. An indicator light will ash
while shifting. Fast ashing means the conditions
were not met to make the desired shift, typically the
vehicle was going too fast, the automatic transmission
was not in neutral, or the clutch pedal was not fully
pressed. Slow ashing means the shift is in progress.
It will stay on when the shift is completed. If for
some reason the transfer cannot make a requested
shift, it will return to the last chosen setting.
Shifting from Two-Wheel High to
Four-Wheel High
Press and release the Four-Wheel High switch. This
can be done at any speed, and the front axle will lock
automatically with some delay.
Shifting from Four-Wheel High to
Two-Wheel High
Press and release the Two-Wheel High switch. This can
be done at any speed, and the front axle will unlock
automatically with some delay.
It is normal to hear and feel your vehicle’s transfer case
shift into Four-Wheel Low. If you shift with the vehicle
stopped, the indicator light may remain ashing slowly. It
may be necessary to shift the transmission momentarily
into REVERSE (R) and DRIVE (D), for an automatic
transmission, or REVERSE (R) and FIRST (1) for
a manual transmission to have the light stop ashing.
2-46

Shifting from Two-Wheel High or
Four-Wheel High to 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 from Two-Wheel High or Four-Wheel High to
Four-Wheel Low, the vehicle must be stopped or moving
less than 3 mph (5 km/h) with the transmission in
NEUTRAL (N) for an automatic transmission or the
clutch pedal pressed for a manual transmission.
The preferred method for shifting into four-wheel low is
to have your vehicle moving 3 mph (5 km/h).
Press and release the Four-Wheel Low switch. You
must wait for the four-wheel low indicator light to stop
ashing and stay on before shifting your transmission
into gear or releasing the clutch pedal.
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.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 slower than
3 mph (5 km/h) and the transmission is in NEUTRAL (N).
The transfer case will shift to Four-Wheel High while
waiting to complete the shift.
Shifting from Four-Wheel Low to
Four-Wheel High or Two-Wheel High
To shift from four-wheel low to Four-Wheel High or
Two-Wheel High, your vehicle must be stopped or
moving less than 3 mph (5 km/h) with the transmission in
NEUTRAL (N) for an automatic transmission or the clutch
pedal pressed for a manual transmission. The preferred
method for shifting out of Four-Wheel Low is to have your
vehicle moving 3 mph (5 km/h).
Press and release the Two-Wheel High or Four-Wheel
High switch. You must wait for the Two-Wheel High
or Four-Wheel High indicator light to stop ashing and
remain on before shifting your transmission into
gear or releasing the clutch pedal.
If the Four-Wheel High switch is pressed when your
vehicle is in gear and/or moving, the Four-Wheel High
indicator light will ash for 30 seconds but will not
complete the shift unless the vehicle is moving slower
than 3 mph (5 km/h) and the transmission is in
NEUTRAL (N).
2-47

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, rst make sure
the vehicle is parked so that it will not roll:
1. Set the parking brake.
2. Start the vehicle or turn the ignition to RUN.
3. Press the foot brake pedal and put the transmission
in NEUTRAL (N).
4. Shift the transfer case to Two-Wheel High.
5. Simultaneously press and hold the Two-Wheel High
and Four-Wheel Low buttons for 10 seconds. The
red NEUTRAL light will come on when the
transfer case shift to NEUTRAL is complete.
6. Start the engine if it is not already running.7. Press and hold the foot brake pedal and Shift the
transmission to REVERSE (R) for one second,
then shift the transmission for one second to
DRIVE (D) for an automatic transmission, or
FIRST (1) for vehicles equipped with a manual
transmission and then let out the clutch. This is to
ensure the transfer case is in NEUTRAL. If not,
repeat this procedure starting at Step 3.
8. Turn the engine off, by turning the key to
ACCESSORY.
9. Place the transmission shift lever in PARK (P) for
an automatic transmission, or FIRST (1) for
vehicles equipped with a manual transmission.
10. Turn the ignition to LOCK.
Shifting Out of NEUTRAL
To shift out of NEUTRAL:
1. Set the parking brake and press and hold the
regular brake pedal.
2. Shift the transmission to NEUTRAL (N) for an
automatic transmission, or press the clutch pedal for
vehicles equipped with a manual transmission.
Then turn the ignition to RUN with the engine off.
3. Press the button for the desired transfer case shift
position (Two-Wheel High, Four-Wheel High, or
Four-Wheel Low).
2-48

Shifting Into Park (P)
(Automatic Transmission)
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. If you have left the engine running, the
vehicle can move suddenly. You or others
could be injured. To be sure your vehicle will
not move, even when you are on fairly level
ground, use the steps that follow. With
four-wheel drive, if your transfer case is in
NEUTRAL, your vehicle will be free to roll,
even if your shift lever is in PARK (P). So, be
sure the transfer case is in a drive gear — not
in NEUTRAL. If you are pulling a trailer, see
Towing a Trailer on page 4-67.1. Hold the brake pedal down with your right foot and
set the parking brake.
2. Move the shift lever into the PARK (P) position by
pulling the shift lever toward you and moving it up
as far as it will go.
3. If your vehicle has four-wheel drive, be sure the
transfer case is in a drive gear — not in
NEUTRAL (N).
4. Turn the ignition key to LOCK.
5. Remove the key and take it with you. If you can
leave your vehicle with the ignition key in your
hand, your vehicle is in PARK (P).
2-50

Leaving Your Vehicle With the Engine
Running (Automatic Transmission)
{CAUTION:
It can be dangerous to leave your vehicle with
the engine running. Your vehicle could move
suddenly if the shift lever is not fully in PARK
(P) with the parking brake rmly set.
If you have four-wheel drive and your transfer
case is in NEUTRAL, your vehicle will be free
to roll, even if your shift lever is in PARK (P).
So be sure the transfer case is in a drive
gear — not in NEUTRAL.
And, if you leave the vehicle with the engine
running, it could overheat and even catch re.
You or others could be injured. Do not leave
your vehicle with the engine running unless
you have to.If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and the
parking brake is rmly set before you leave it. After you
move the shift lever into PARK (P), hold the regular
brake pedal down. Then, see if you can move the shift
lever away from PARK (P) without rst pulling it
toward you. If you can, it means that the shift lever was
not fully locked into PARK (P).
Torque Lock (Automatic Transmission)
If you are parking on a hill and you do not shift your
transmission into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl
in the transmission. You may nd it difficult to pull the
shift lever out of PARK (P). This is called “torque
lock.” To prevent torque lock, set the parking brake and
then shift into PARK (P) properly before you leave
the driver’s seat. To nd out how, see “Shifting
Into PARK (P)” listed earlier in this section.
When you are ready to drive, move the shift lever out of
PARK (P) before you release the parking brake.
If torque lock does occur, you may need to have another
vehicle push yours a little uphill to take some of the
pressure from the parking pawl in the transmission, so
you can pull the shift lever out of PARK (P).
2-51

Shifting Out of Park (P)
(Automatic Transmission)
Your vehicle has an automatic transmission shift lock
control system which locks the shift lever in PARK (P)
when the ignition is in the LOCK position. You have
to fully apply your regular brakes before you can shift
from PARK (P) when the ignition is in RUN. See
Automatic Transmission Operation on page 2-24and
“Torque Lock” underShifting Out of Park (P) (Automatic
Transmission) on page 2-52.
If your vehicle has an Allison Transmission
®, the
transmission is equipped with a park pawl designed to
hold the higher weight of commercial medium duty
trucks. Therefore, the Allison Transmission
®uses larger
parts than other automatic transmissions. These
larger parts may sometimes make a clunk noise when
the selector lever is moved from DRIVE (D) or
REVERSE (R) to PARK (P). This is normal and there is
no damage occurring during these shifts.If you cannot shift out of PARK (P), ease pressure on
the shift lever and push the shift lever all the way up into
PARK (P) as you maintain brake application. Then,
move the shift lever into the gear you want.
If you ever hold the brake pedal down but still can’t shift
out of PARK (P), try this:
1. Turn the key to ACCESSORY. There is no shift
interlock in this key position.
2. Apply and hold the brake until the end of Step 4.
3. Shift the transmission to NEUTRAL (N).
4. Start the vehicle and then shift to the gear
you want.
5. Have the system xed as soon as you can.
2-52