wheel GMC SIERRA 2007 User Guide

Active Fuel Management™
Your vehicle’s V8 engine may have Active Fuel
Management™. This system allows the engine to
operate on either all or half of its cylinders,
depending on the driving conditions.
When less power is required, such as cruising at a
constant vehicle speed, the system will operate
in the half cylinder mode, allowing your vehicle to
achieve better fuel economy. When greater
power demands are required, such as accelerating
from a stop, passing, or merging onto a freeway,
the system will maintain full-cylinder operation.
Your vehicle has an Active Fuel Management™
indicator. For more information on using this
display seeDIC Operation and Displays (With DIC
Buttons) on page 268orDIC Operation and
Displays (Without DIC Buttons) on page 275.
Automatic Transmission Operation
If your vehicle is has an automatic transmission,
it has an electronic shift position indicator
within the instrument panel cluster. This display
comes on when the ignition key is turned to
the RUN position.There are several different positions for the
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 the engine
because your vehicle cannot move easily.
Hydra-Matic®4-Speed Automatic Transmission
Allison Transmission®or Hydra-Matic®6-Speed
Automatic Transmission
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When parked on a hill, especially when the vehicle
has a heavy load, you might notice an increase in
the effort to shift out of Park. See Torque Lock
(Automatic Transmission) underShifting Into
Park (P) on page 163for more information.
{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) on page 163.Ifyou
are pulling a trailer, seeTowing a Trailer
on page 445.
{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 Drive High or
Four-Wheel Drive High or Four-Wheel Drive
Low — not in NEUTRAL. SeeShifting Into
Park (P) on page 163.
REVERSE (R):Use this gear to back up.
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 422.
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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. It
provides the best fuel economy for your vehicle. 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 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 389.
Your vehicle has a shift stabilization feature that
adjusts the transmission shifting to the current
driving conditions in order to reduce rapid upshifts
and downshifts.
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SECOND (2):This position reduces vehicle speed
even more than THIRD (3) without using your
brakes. 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 the brakes off and on.
If you manually select SECOND (2) in an automatic
transmission, the transmission will start in second
gear. You can 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):For the Hydra-Matic
®4-Speed
transmission this position reduces vehicle speed
even more than SECOND (2) without using
the brakes. 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 does not shift into rst gear
until the vehicle is going slowly enough.For an Allison Transmission
®or Hydra-Matic®
6-Speed transmission, this position reduces
vehicle speed without using your brakes. You can
use it for major/severe downgrades and off-road
driving where the vehicle would otherwise
accelerate due to steepness of grade. When you
shift to FIRST (1) it provides the lowest gear
appropriate to your current road speed and
continues to downshift as the vehicle slows,
eventually downshifting to FIRST (1) gear.
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.
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Grade Braking is not available when the Range
Selection Mode is active. SeeTow/Haul Mode on
page 144.
While using the Range Selection mode feature,
cruise control and the Tow/Haul mode can
be used.
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.
Low Traction Mode
If your vehicle has the Allison Transmission®,or
the Hydra-Matic®6-Speed Automatic
Transmission, it has a Low Traction Mode that
assist in vehicle acceleration when road conditions
are slippery, such as with ice or snow. While
the vehicle is at a stop, select the second gear
range using the Range Selection system. This will
limit torque to the wheels after it detects wheel
slip, preventing the tires from spinning.
Tow/Haul Mode
If your vehicle has an automatic transmission, it
has a tow/haul mode. If your vehicle has an Allison
or Hydra-Matic
®6-speed automatic transmission
see “Tow/Haul Mode (Allison or Hydra-Matic®
6-Speed Automatic Transmission®) following.
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Four-Wheel Drive
If your 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 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 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.
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.
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.
147

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 265
Some delay between shifting and when the
indicator light comes on is normal.
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeRecreational Vehicle Towing on page 439
Towing Your Vehicle on page 439
Notice:Driving on clean, dry pavement in
four-wheel drive for an extended period of time
can cause premature wear on your vehicle’s
powertrain. Do not drive on clean, dry
pavement in Four-Wheel Drive for extended
periods of time.
4
n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra
torque. You may never need Four-Wheel-Drive
Low. It sends maximum power to all four wheels.
You might choose Four-Wheel-Drive 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-Drive High. The
transmission gear shift feel is exaggerated.
148

A parking brake symbol
is located next to the
N (NEUTRAL) symbol
as a reminder to set the
parking brake before
shifting the transfer case
in 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 162.N (NEUTRAL):Shift to this setting only when
your vehicle needs to be towed. SeeRecreational
Vehicle Towing on page 439orTowing Your
Vehicle on page 439
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.
149

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, and make the transfer case harder to
shift and run noisier.
If the transfer case shifter is in the 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 NEUTRAL. This will
realign the gear teeth in the transfer case and
allow you to complete the shift.
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 your
vehicle has warmed up.
While in Four-Wheel-Drive High, your vehicle
can be driven at any posted legal speed limit.
150

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 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 162.
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 will end up in
NEUTRAL. This is normal, and is a function of
the gear teeth aligning in your transfer
case. When this happens, make sure the
engine is on, shift your transmission
momentarily to drive and back to NEUTRAL,
and then complete the 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.
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.
151