2007 GMC SIERRA brake

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.
144

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 266for more
information.
Also see “Tow Haul Mode” underTowing a Trailer
on page 445for 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 andAutomatic Transmission Operation
on page 138for 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. See the diesel supplement for
information on Cruise Grade Braking.
Also seeTowing a Trailer on page 445for more
information.
146

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

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

4n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra
torque. You may never need this setting. It sends
maximum power to all four wheels. You might
choose Four-Wheel-Drive Low while driving
off-road in deep sand, deep mud, deep snow, and
while climbing or descending steep hills.
StabiliTrak
®will not engage in this mode.
{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 the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 439or
Towing Your Vehicle on page 439for more
information.If the SERVICE 4–Wheel Drive message stays on,
you should take your vehicle to your dealer for
service. See “Service 4–Wheel Drive message”
underDIC Warnings and Messages on page 279.
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 RUN and the vehicle must be
stopped or moving less than 3 mph (5 km/h) with
the transmission in NEUTRAL (N). The preferred
method for shifting into Four-Wheel-Drive Low
is to have your vehicle moving 1 to 2 mph
(1.6 to 3.2 km/h). Turn the knob to the
Four-Wheel-Drive Low position.
153

If the knob is turned to the Four-Wheel-Drive High,
or Two-Wheel-Drive High switch position when
your vehicle is in gear and/or moving, the
Four-Wheel-Drive High, or Two-Wheel-Drive High
indicator light will ash for 30 seconds but will
not complete the shift unless your vehicle is
moving less than 3 mph (5 km/h) and the
transmission is in NEUTRAL (N).
Shifting into NEUTRAL
To shift the transfer case to NEUTRAL do
the following:
1. Make sure the vehicle is parked so that it will
not roll.
2. Set the parking brake and press and hold the
regular brake pedal. SeeParking Brake on
page 162for more information.
3. Start the vehicle or turn the ignition to RUN.
4. Shift the transmission to NEUTRAL (N).5. Shift the transfer case to
Two-Wheel-Drive High.
6. Turn the transfer case dial clockwise to
NEUTRAL till it stops and hold it for
10 seconds. Then slowly release the dial to
the four low position. The NEUTRAL light will
come on when the transfer case shift to
NEUTRAL is complete.
7. If the engine is running, verify that the
transmission is in NEUTRAL (N) by shifting
the transmission to REVERSE (R) for
one second, then shift the transmission to
DRIVE (D) for one second.
8. Turn the ignition to ACCESSORY, which will
turn the engine off.
9. Place the transmission shift lever in PARK (P).
10. Release the parking brake prior to moving
the vehicle.
11. Turn the ignition to LOCK.
155

Shifting Out of NEUTRAL
To shift out of NEUTRAL do the following:
1. Set the parking brake and apply the regular
brake pedal.
2. Shift the transmission to NEUTRAL (N) and
turn the ignition to RUN with the engine off.
3. Turn the transfer case dial to
Two-Wheel-Drive High.
After the transfer case has shifted out of
NEUTRAL the NEUTRAL light will go out.
4. Release the parking brake prior to moving the
vehicle.
Notice:Shifting the transmission into gear
before the requested mode indicator light has
stopped ashing could damage the transfer
case. To help avoid damaging your vehicle,
always wait for the mode indicator lights
to stop ashing before shifting the
transmission into gear.
5. Start the engine and shift the transmission to
the desired position.Excessively shifting the transfer case into or out of
the different modes may cause the transfer
case to enter the shift protection mode. This will
protect the transfer case from possible damage
and will only allow the transfer case to respond to
one shift per 10 seconds. The transfer case
may stay in this mode for up to three minutes.
Automatic Transfer Case
The transfer case knob
is located next to the
steering column.
For information on StabiliTrak
®, seeStabiliTrak®
System on page 381.
156

4n(Four-Wheel-Drive Low):This setting also
engages the front axle and delivers extra
torque. You may never need this setting. 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.
StabiliTrak
®will not engage in this mode. See
StabiliTrak®System on page 381for more
information.
{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 the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 439or
Towing Your Vehicle on page 439for more
information.
If the SERVICE 4–Wheel Drive message stays on,
you should take your vehicle to your dealer for
service. See “Service 4–Wheel Drive message”
underDIC Warnings and Messages on page 279.
Shifting Into Four-Wheel-Drive High or
AUTO (Automatic Four-Wheel Drive)
Turn the knob to the Four-Wheel-Drive High or
AUTO position. This can be done at any speed,
except when shifting from Four-Wheel-Drive
Low, and the indicator light will ash while shifting.
It will remain on when the shift is completed.
158