2006 GMC SIERRA engine

Automatic Transmission Operation
If your vehicle is has an automatic transmission, it
features an electronic shift position indicator within the
instrument panel cluster. This display must be powered
anytime the shift lever is moved out of PARK (P).
SeeFuses and Circuit Breakers on page 5-123.
There are several different positions for your shift lever.
See “Range Selection Mode” later in this section.PARK (P):This position locks your rear wheels. It is the
best position to use when you start your engine because
your vehicle cannot move easily. If your vehicle has the
Allison Transmission®, with the Power Takeoff (PTO),
use PARK (P) when starting. The Allison Transmission®
has a park pawl that is designed to hold the 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.
When parked on a hill, especially when loaded, you may
notice an increase in the effort to shift out of Park. See
Torque Lock (Automatic Transmission) underShifting
Into Park (P) (Automatic Transmission) on page 2-53for
more information.
Automatic Transmission
Allison Transmission®
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{CAUTION:
It is 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.
Do not leave your vehicle when the engine is
running unless you have to. 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, always set your parking
brake and move the shift lever to PARK (P). See
Shifting Into Park (P) (Automatic Transmission)
on page 2-53. If you are pulling a trailer, see
Towing a Trailer on page 4-67.
{CAUTION:
If you have four-wheel drive, your vehicle will
be free to roll — even if your shift lever is in
PARK (P) — if your transfer case is in
NEUTRAL. So, be sure the transfer case is
in a drive gear, two-wheel high (2H) or
four-wheel high (4H) or four-wheel
low (4L) — not in NEUTRAL. SeeShifting
Into Park (P) (Automatic Transmission) on
page 2-53.
REVERSE (R):Use this gear to back up. If your vehicle
has the Allison Transmission
®, the R on the shift display,
may blink if the shift inhibitor is active.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
To rock your vehicle back and forth to get out of snow,
ice, or sand without damaging your transmission, seeIf
Your Vehicle is Stuck in Sand, Mud, Ice or Snow on
page 4-46.
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NEUTRAL (N):In this position, your engine does not
connect with the wheels. To restart when you are
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
{CAUTION:
Shifting into a drive gear while your engine is
running at high speed is dangerous. Unless
your foot is rmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
Notice:Shifting out of PARK (P) or NEUTRAL (N)
with the engine running at high speed may damage
the transmission. The repairs would not be covered
by your warranty. Be sure the engine is not running
at high speed when shifting your vehicle.DRIVE (D):This position is for normal driving. If you
need more power for passing, and you are:
Going less than about 35 mph (55 km/h), push your
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.
DRIVE (D) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road driving.
You may want to shift the transmission to THIRD (3) or,
if necessary, a lower gear selection if the transmission
shifts too often.
If your vehicle has the Allison Transmission
®, it will
shift into rst range when DRIVE (D) is selected. As
vehicle speed increases, the transmission will upshift
automatically through each available range up to
SIXTH (6). As the vehicle slows, the transmission will
downshift automatically.
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The Allison Transmission®uses 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 will be
able to maintain vehicle speed by analyzing things such
as throttle position, vehicle load, and hill grade. If the
shift stabilization feature determines that current vehicle
speed cannot be maintained, the transmission does not
upshift and instead holds the current gear. In some
cases, this may appear to be a delayed shift, however
the transmission is operating normally.
The Allison Transmission
®also uses adaptive shift
controls. Adaptive shift controls continually compares
key shift parameters to pre-programmed ideal shift
conditions. The Allison Transmission
®constantly makes
adjustments to improve vehicle performance according
to the way the vehicle is being used, such as with a
heavy load. During this adaptive shift controls process,
some shifts may feel different as the transmission
determines optimum settings for a particular shift.
MANUAL MODE (M):This position, is available on
vehicles with the Allison Transmission
®. It lets drivers
select the range of gears appropriate for current driving
conditions. If your vehicle has this feature, see Range
Select Mode (Allison Transmission
®) later in this section.THIRD (3):This position is also used for normal driving,
however it offers more power and lower fuel economy
than DRIVE (D).
SECOND (2):This position gives you more power
but lower fuel economy. You can use SECOND (2) on
hills. It can help control your speed as you go down
steep mountain roads, but then you would also want
to use your brakes off and on.
If you manually select SECOND (2) in an automatic
transmission, the transmission will start in second gear.
You may use this feature for reducing the speed of
the rear wheels when you are trying to start your vehicle
from a stop on slippery road surfaces.
FIRST (1):This position gives you even more power (but
lower fuel economy) than SECOND (2). You can use it on
very steep hills, or in deep snow or mud. If the shift lever
is put in FIRST (1) while the vehicle is moving forward,
the transmission will not shift into rst gear until the
vehicle is going slowly enough.
Notice:Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator pedal
may damage the transmission. If you are stuck, do
not spin the tires. When stopping on a hill, use the
brakes to hold the vehicle in place.
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Range Selection Mode
(Allison Transmission®)
If your truck has an Allison Transmission®your vehicle
is equipped with a Range Selection System.
To use this feature, do the following:
1. Move the shift lever to the MANUAL MODE (M).
When in the MANUAL MODE, the transmission’s
current gear range will be the highest attainable
range with all the lower gears available.
2. Press the plus/minus buttons to upshift or downshift
selecting the desired range of gears for your current
driving conditions.The Range Selection Mode allows you to control the
vehicle’s engine and vehicle speed while driving
down hill by allowing you to select a desired gear.
The DIC shows the six available ranges with the
highest attainable range shown in brackets. See
Driver Information Center (DIC) on page 3-52and
DIC Operation and Displays on page 3-53for more
information.
While using the Range Selection mode feature, cruise
control and the Tow/Haul mode can be used.
Low Traction Mode
(Allison Transmission®)
If your vehicle has the DURAMAX®diesel engine and the
Allison Transmission®, it is equipped with a Low Traction
Mode that assists in vehicle acceleration when road
conditions are slippery, such as ice or snow. While at a
stop, selecting the second gear range using the Range
Selection system, will allow the Allison Transmission
®
to limit torque to the wheels after it detects wheel slip,
preventing the tires from spinning.
Notice:Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator pedal
may damage the transmission. If you are stuck, do
not spin the tires. When stopping on a hill, use the
brakes to hold the vehicle in place.
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Cold Weather Operation
(Allison Transmission®)
On cold days, approximately 32°F (0°C) or colder, your
automatic transmission is designed to shift differently.
The transmission uses a warm-up mode shift schedule
until the engine reaches normal operating temperature.
While the transmission is in warm-up mode it is normal for
transmission upshifts to be delayed or held longer. This
feature improves heater performance by giving quicker
vehicle warm-ups.
When temperatures are below−13°F (−25°C), the
transmission will prevent certain operations to protect
against damage. When active the DIC will display
the message “Trans in Warm-up”.
SeeDIC Warnings and Messages on page 3-55for
more information.
Tow/Haul Mode
If your vehicle has an automatic transmission, it may
have a Tow/Haul mode. If your vehicle has an
Allison Transmission
®see “Tow/Haul Mode (Allison
Transmission®) following. 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.
The selector button is located on the end of the shift
lever. Turn the Turn Tow/Haul on and off by pressing
the button. When the Tow/Haul is on, a light on the
instrument panel cluster will come on.
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Grade Braking and Cruise Grade
Braking (Allison Transmission®)
Grade Braking and Cruise Grade Braking assists when
driving on a downhill grade. It maintains the vehicle’s
speed by automatically implementing a shift schedule
that uses the engine and the transmission to slow the
vehicle. This reduces wear on the brakes system and
increases control of the vehicle. The system constantly
monitors the vehicle’s speed, acceleration, engine torque,
and brake pedal usage. It detects when the truck is on a
downhill grade and the driver’s desire to slow down by
pressing the brake.Cruise Grade Braking is available on the
6.6L DURAMAX
®diesel engine. Cruise Grade
Braking monitors a vehicle’s cruise state, engine torque,
acceleration, vehicle speed, and the cruise set speed.
Using this information, it detects when the truck is
accelerating on a downhill grade and will automatically
downshift to slow the vehicle if it exceeds the cruise set
speed by a certain amount.
SeeCruise Control on page 3-10for more information.
The Tow/Haul mode and Grade Braking shift modes can
be activated by pressing the button on the front of the
shift control stalk. If your vehicle has the DURAMAX
®
Diesel Engine or the 8.1L Vortec gasoline engine, Grade
Braking is only available while the Tow/Haul Mode is
selected. While in the Range Selection Mode, Grade
Braking is deactivated allowing the driver to select a
desired gear.
SeeAutomatic Transmission Operation on page 2-26for
more information.
Also seeTowing a Trailer on page 4-67for more
information.
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Manual Transmission Operation
Five-Speed
(VORTEC™ 6.0L V8 Engine)
Here is how to operate
your transmission.
FIRST (1) is intended only for heavy loads or trailer
towing and is not recommended for normal driving.
During the rst 500 miles (805 km) of vehicle use, start
your vehicle moving in FIRST (1). This allows clutch
components to break-in properly.
FIRST (1):Press the clutch pedal and shift into
FIRST (1). Then, slowly let up on the clutch pedal as
you press the accelerator pedal. Shift into FIRST (1) only
when the vehicle is below 5 mph (8 km/h). If you try to
shift down into FIRST (1) at excessive vehicle speeds,
the shift lever will not move into FIRST (1) until vehicle
speed is reduced.SECOND (2):Press the clutch pedal and shift into
SECOND (2). Then, slowly let up on the clutch pedal
as you press the accelerator pedal.
You can shift into SECOND (2) when you are going less
than 20 mph (32 km/h). If you have come to a complete
stop and it is hard to shift into SECOND (2), put the shift
lever into NEUTRAL and let up on the clutch. Press the
clutch pedal back down. Then shift into SECOND (2).
If you try to downshift into SECOND (2) at excessive
vehicle speeds, the shift lever will not move into the
SECOND (2) position until the vehicle speed is reduced.
THIRD (3):Press the clutch pedal and shift into
THIRD (3). Then, slowly let up on the clutch pedal
as you press the accelerator pedal.
FOURTH (4) and FIFTH (5):Shift into the higher
forward gears the same way you do for THIRD (3).
Slowly let up on the clutch pedal as you press the
accelerator pedal.
To stop, let up on the accelerator pedal and press the
brake pedal. Just before the vehicle stops, press the
clutch pedal and the brake pedal, and shift to NEUTRAL.
NEUTRAL:Use this position when you start or idle
your engine.
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