2009 GMC SIERRA engine

{CAUTION:
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 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 Neutral.
SeeShifting Into Park on page 2-52.
R (Reverse):Use this gear to back up.
Notice: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, seeIf
Your Vehicle is Stuck in Sand, Mud, Ice, or Snow on
page 4-30.
N (Neutral):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.
{CAUTION:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is rmly 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.
Notice: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 (Drive):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 35 mph (55 km/h), push the
accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
By doing this, the vehicle shifts down to the next
gear and has more power.
2-30

D (Drive) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road driving.
You might want to 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 underLoss of
Control on page 4-11
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.
Adaptive shift controls continually compares key shift
parameters to pre-programmed ideal shifts stored in the
transmissions 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 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 Allison
Transmission®and Hydra-Matic®6-Speed 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 (Manual Mode):This position is available on
vehicles with the Allison Transmission
®or Hydra-Matic®
6-Speed transmission. It lets drivers select the range
of gears appropriate for current driving conditions.
If the vehicle has this feature, see Range Select Mode
(Allison Transmission
®or Hydra-Matic®6-Speed
transmission) later in this section.
3 (Third):This position is also used for normal driving.
It reduces vehicle speed more than D (Drive) without
using the brakes. You might choose 3 (Third) instead
of D (Drive) when driving on hilly, winding roads,
when towing a trailer, so there is less shifting between
gears and when going down a steep hill.
2 (Second):This position reduces vehicle speed even
more than 3 (Third) without using the brakes. You can
use 2 (Second) on hills. It can help control vehicle speed
as you go down steep mountain roads, but then you
would also want to use the brakes off and on.
2-31

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.
Also seeTowing a Trailer on page 4-51for more
information.
Cruise Grade Braking (Allison
Transmission®or Hydra-Matic®
6-Speed Automatic Transmission)
Cruise Grade Braking assists when driving on a
downhill grade. It maintains vehicle speed by
automatically implementing a shift schedule that
uses the engine and the transmission to slow the
vehicle. Cruise Grade Braking operates while Cruise
Control is engaged in Tow/Haul mode to assist in
maintaining vehicle speed under loaded vehicle
conditions. It utilizes vehicle acceleration and deviation
from desired speed to determine the correct gear for the
operating condition. If vehicle speed is above the desired
speed the transmission will downshift to slow the vehicle.
If vehicle speed is near or below desired speed the trans
will upshift, allowing vehicle speed to increase.
While in the Range Select Mode (RSM) mode, cruise
grade braking is not available.
SeeAutomatic Transmission Operation on page 2-28.
2-36

Four-Wheel Drive
If the 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 following
before using Four-Wheel Drive. See the appropriate
text for the transfer case in the 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.
If the vehicle has StabiliTrak
®, shifting into
Four-Wheel-Drive Low will turn Traction Control and
StabiliTrak
®off. SeeStabiliTrak®System on page 4-6.
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.
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.
SeeFour-Wheel-Drive
Light on page 3-51.
2-37

N (Neutral):Shift to this setting only when the vehicle
needs to be towed. SeeRecreational Vehicle Towing
on page 4-45orTowing Your Vehicle on page 4-45.
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.
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,
make the transfer case harder to shift, and run
noisier.
If the transfer case shifter is in the N (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
N (Neutral). This will realign the gear teeth in the
transfer case and allow you to complete the shift.
2-39

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 the vehicle
has warmed up.
While in Four-Wheel-Drive High, the vehicle can be
driven at any posted legal speed limit.
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 N (Neutral).
{CAUTION:
Shifting the transfer case to Neutral can cause
the vehicle to roll even if the transmission is in
P (Park). 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
the transfer case will end up in N (Neutral). This is
normal, and is a function of the gear teeth aligning in
the transfer case. When this happens, make sure the
engine is on, shift the transmission momentarily to
D (Drive) and back to N (Neutral), and then complete
the transfer case 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 N (Neutral).
Shift the transfer case in one continuous motion into or
out of the N (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 4-45
Towing Your Vehicle on page 4-45
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 the vehicle to your dealer/retailer
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.
2-41

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.
Shifting Into Four-Wheel Drive Low
When Four-Wheel-Drive Low is engaged, vehicle speed
should be kept below 45 mph. Extended high-speed
operation in Four-Wheel-Drive Low may damage
or shorten the life of the drivetrain.
To shift to the Four-Wheel-Drive Low position, the
ignition must be in ON/RUN and the vehicle must be
stopped or moving less than 3 mph (5 km/h) with the
transmission in N (Neutral). The preferred method for
shifting into Four-Wheel-Drive Low is to have the vehicle
moving 1 to 2 mph (1.6 to 3.2 km/h). Turn the knob to the
Four-Wheel-Drive Low position. You must wait for the
Four-Wheel-Drive Low indicator light to stop ashing
and remain on before shifting the transmission in gear.Notice:Shifting the transmission into gear before
the requested mode indicator light has stopped
ashing could damage the transfer case. To help
avoid damaging the vehicle, always wait for the
mode indicator lights to stop ashing before
shifting the transmission into gear.
It is typical for the vehicle to exhibit signicant
engagement noise and bump when shifting between
Four-Wheel-Drive Low and Four-Wheel-Drive High
ranges or from transfer case N (Neutral) with the
engine running.
If the knob is turned to the Four-Wheel-Drive Low
position when the vehicle is in gear and/or moving,
the Four-Wheel-Drive Low indicator light will ash for
30 seconds and not complete the shift unless the vehicle
is moving less than 3 mph (5 km/h) and the transmission
is in N (Neutral). After 30 seconds the transfer case
will shift to Four-Wheel-Drive High mode.
2-43