2007 GMC SIERRA CLASSIC Owners Manual

Range Selection Mode
(Allison Transmission®)
If your truck has an Allison Transmission®your
vehicle has 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 select the
desired range of gears for your current
driving conditions.
The Range Selection Mode allows you to
control the 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.
SeeDriver Information Center (DIC) on page 265
andDIC Operation and Displays on page 266
for more information.
While using the Range Selection mode, cruise
control and the Tow/Haul mode can be used.
Grade braking is not available while in the Range
Selection mode. SeeTow/Haul Mode on
page 147for more information.
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Low Traction Mode
(Allison Transmission®)
If your vehicle has the DURAMAX®diesel engine
and the Allison Transmission®,ithasaLow
Traction Mode that assists in vehicle acceleration
when road conditions are slippery, such as
with 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. The repair will not be covered by
your warranty. If you are stuck, do not spin
the tires. When stopping on a hill, use the
brakes to hold the vehicle in place.
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 270for
more information.
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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 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.
SeeTow/Haul Mode Light on page 264for
more information.
If your vehicle has the Performance
Package-Enhanced Towing, activating the manual
selectable ride will adjust the shock absorber
characteristics to enhance the ride and handling of
the vehicle for towing or hauling heavy loads.
Also see Tow Haul Mode underTowing a Trailer
on page 429for more information.
147

Tow/Haul Mode (Allison
Transmission®)
If your vehicle has an Allison Transmission®,it
may have a Tow/Haul mode. 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 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.
SeeTow/Haul Mode Light on page 264for more
information.
Also see “Tow Haul Mode” underTowing a Trailer
on page 429for more information.
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 using 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.
148

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 217for more
information.
The Tow/Haul mode and Grade Braking shift
modes can be activated by pressing the button on
the end 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 range of gears.
SeeAutomatic Transmission Operation on
page 140for more information.
Also seeTowing a Trailer on page 429for more
information.
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.
149

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).
Notice:If you try to shift down into FIRST (1) at
excessive vehicle speeds, clutch or engine
damage could occur. Do not shift into FIRST (1)
unless you are going less than 5 mph (8km/h).
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).
Notice:If you try to shift down into
SECOND (2) at excessive vehicle speeds,
clutch or engine damage could occur. Do not
shift into SECOND (2) unless you are going
less than 20 mph (32km/h).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.
REVERSE (R):To back up, rst press down the
clutch pedal. Wait for the vehicle to stop moving
and then, shift into REVERSE (R). Let up on
the clutch pedal slowly while pressing the
accelerator pedal.
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.
150

Also, use REVERSE (R), along with the parking
brake, when turning off your engine and parking
your vehicle.
Five-Speed (VORTEC™ 4.3L V6 and
4.8L V8 Engines)
Here is how to operate your transmission:
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.
You can shift into FIRST (1) 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 FIRST (1),
put the shift lever into NEUTRAL and let up on
the clutch. Press the clutch pedal back down. Then
shift into FIRST (1).
Notice:If you try to shift down into FIRST (1)
at excessive vehicle speeds, clutch or
engine damage could occur. Do not shift into
FIRST (1) unless you are going less than
20 mph (32km/h).
SECOND (2):Press the clutch pedal as you let
up on the accelerator pedal and shift into
SECOND (2). Then, slowly let up on the clutch
pedal as you press the accelerator pedal.THIRD (3), FOURTH (4) and FIFTH (5):Shift into
THIRD (3), FOURTH (4) and FIFTH (5) the same
way you do for SECOND (2). 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.
REVERSE (R):To back up, rst press down the
clutch pedal. Wait for the vehicle to stop moving
and then, shift into REVERSE (R). Let up on
the clutch pedal slowly while pressing the
accelerator pedal.
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.
Also, use REVERSE (R), along with the parking
brake, when turning off your engine and parking
your vehicle.
151

Shift Speeds
{CAUTION:
If you skip a gear when you downshift,
you could lose control of your vehicle.
You could injure yourself or others. Do
not shift down more than one gear at a
time when you downshift.
Do not allow the engine Revolutions Per Minute
(RPM) to overspeed and enter the tachometer red
lines. Engine overspeed occurs when downshifting,
or descending a grade, at too high a vehicle
speed. When going down steep grades, always
select a gear at least one position lower than you
would use on climbing a grade. This will allow
the vehicle’s engine to provide some braking and
help to slow the vehicle as it goes down the
grade. Monitor your vehicle speed, acceleration
and engine RPM while applying the brakes as you
go down the grade to ensure you have complete
control over the vehicle.If your engine speed drops below 600 rpm, or if
the engine is not running smoothly, you should
downshift to the next lower gear. When operating
on slippery surfaces, downshift at lower than
normal vehicle speeds to prevent the tires from
slipping.
In vehicles that have a bench seat, move the
tallest beverage containers to the right cupholder
to provide additional clearance for the shift
lever.
For vehicles that have a center console, the front
cup holder pulls out and turns 180° to provide
additional clearance between tall beverage
containers and the shift lever.
Up-Shift Light
If your vehicle has 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.
152