automatic transmission CHEVROLET SILVERADO 2005 1.G User Guide

Grade braking is active and automatic both in Tow/Haul
mode and normal shift mode. Grade braking is more
aggressive when in Tow/Haul mode and can
automatically downshift to SECOND (2), which is
different than grade braking while in normal shift mode
where automatic downshifts are limited to FOURTH (4).
The tachometer for both the diesel and gasoline
engine shows a dashed red zone and a solid red zone.
The dashed red zone indicates where a transmission
shift occurs for full engine power. When using grade
braking, the transmission’s shift point is adjusted to just
prior to the solid red zone, providing the benet of
additional engine braking.
Grade braking driving within the dashed red zone is
normal, both the diesel and gasoline engine have been
designed for this grade braking feature. Do not allow
the engine to go into the solid red zone. Apply the
vehicle’s brakes for a short time to slow down if you are
driving on a long hill and the tachometer needle
enters the solid red zone. SeeTowing a Trailer on
page 4-69for more information.Overdrive Disable
(Allison®Transmission Only)
If your vehicle has an Allison Transmission®, you may
have the overdrive disable feature. The overdrive disable
feature prevents the transmission from shifting into
FIFTH (5) gear. The selector button is located on the
end of the column shift lever. You can turn overdrive
disable on and off by pressing and holding the button at
the end of the column shift lever until the indicator
light, on the instrument panel, illuminates.
If your vehicle has both Tow/Haul and overdrive disable,
tap the button once to enable or disable Tow/Haul,
and press and hold the button to enable or disable
overdrive disable.
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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 4-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.
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.
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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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 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).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.
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.
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You can choose among four driving settings:
AUTO 4WD:This setting is ideal for use when road
surface traction conditions are variable. When driving
your vehicle in AUTO four-wheel drive, the front axle is
engaged, but the vehicle’s power is sent to the rear
wheels. 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 2-51.
N (NEUTRAL):Shift the vehicle’s transfer case to
N (NEUTRAL) only when towing your vehicle.
SeeRecreational Vehicle Towing on page 4-63or
Towing Your Vehicle on page 4-63for 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.
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You can chose among three driving settings:
2
m(Two-Wheel High):This setting is for driving in
most street and highway situations. Your front axle is not
engaged in two-wheel drive.
{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 2-51.
(N) NEUTRAL:Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-63orTowing
Your Vehicle on page 4-63for more information.
4
m(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 depressed.
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.
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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.
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 depressed 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.
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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 depressed 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).
{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 2-51.
2-49

Shifting into NEUTRAL
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).
4. After the transfer case has shifted out of NEUTRAL
the red light will go out.
5. Release the parking brake.
6. You may start the engine and shift the transmission
to the desired position. Excessively shifting the
transfer case into or out of the different modes may
cause the transfer case to enter the shift protection
mode. This will protect the transfer case from
possible damage and will only allow the transfer
case to respond to one shift per 10 seconds.
The transfer case may stay in this mode for up to
three minutes.
7. After the transfer case has shifted out of NEUTRAL
the red light will go out.
2-50

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, seeTowing a Trailer on page 4-69.1. 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).
2-52

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).
2-53