2010 GMC SIERRA Owner's Manual

To use this feature, do the following:1. Move the shift lever to M (Manual Mode).
2. Press the plus/minus buttons, located on the steering column shift lever, to select the desired
range of gears for current driving conditions.
When M (Manual Mode) is selected a number displays
next to the M, indicating the current gear.
This number is the highest gear that can be used.
However, the vehicle can automatically shift to lower
gears as it adjusts to driving conditions. This means
that all gears below that number are available. When
5 (Fifth) is selected, 1 (First) through 5 (Fifth) gears are
automatically shifted by the vehicle, but 6 (Sixth) cannot
be used until the plus/minus button located on the
steering column lever is used to change to the gear.
Grade Braking is not available when Range Selection
Mode is active. See Tow/Haul Mode on page 3‑34.
While using Range Selection Mode, 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 the vehicle 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 can 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 Range Selection Mode.
This will limit torque to the wheels after it detects wheel
slip, preventing the tires from spinning.
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Tow/Haul Mode
Vehicles with an automatic transmission have a tow/
haul mode. The 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 4‑49for more
information. Also see Tow Haul Mode under
Towing a Trailer
on
page 5‑50for more information.
Tow/Haul Mode (Allison Transmission®
or Hydra-Matic®6-Speed Automatic
Transmission)
Vehicles with an Allison or Hydra-Matic®6-speed
automatic transmission®have a tow/haul mode. The
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.
3-34

Turn the tow/haul mode on and off by pressing the
button, located on the end of the shift lever. When the
tow/haul is on, a light on the instrument panel cluster
will come on.
SeeTow/Haul Mode Light
on page 4‑49for more
information.
Also see “Tow Haul Mode” underTowing a Trailer
on
page 5‑50for more information.
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 and
Automatic Transmission Operation
on page 3‑28for
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 see
Towing a Trailer
on page 5‑50for 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.
See Automatic Transmission Operation on page 3‑28.
3-35

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. See StabiliTrak®System on page 5‑6.
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 floor to the right of
the driver. Use this lever to shift into and out of
Four-Wheel Drive.
3-36

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 4‑49.
Some delay between shifting and when the indicator
light comes on is normal.
Recommended Transfer Case Settings
Driving Conditions Transfer Case Settings
2m 4m4n N
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*See Recreational Vehicle Towing
on page 5‑43or
Towing Your Vehicle on page 5‑43
Notice: Driving on clean, dry pavement in
four-wheel drive for an extended period of time can
cause premature wear on the 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.
If the vehicle has StabiliTrak
®, shifting into
Four-Wheel-Drive Low will turn Traction Control and
StabiliTrak
®off. See StabiliTrak®System on page 5‑6.
3-37

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
into N (Neutral).
{WARNING:
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 3‑50. N (Neutral) :
Shift to this setting only when the vehicle
needs to be towed. See Recreational Vehicle Towing
on
page 5‑43or Towing Your Vehicle on page 5‑43.
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.
3-38

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.
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.
3-39

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).
{WARNING:
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. See Parking
Brake on page 3‑50.
.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.
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.
3-40