2009 GMC SIERRA 1500 trailer

Starting and Operating
Your Vehicle
New Vehicle Break-In
Notice:The vehicle does not need an elaborate
break-in. But it will perform better in the long run if
you follow these guidelines:
Keep your speed at 55 mph (88 km/h) or less for
the rst 500 miles (805 km).
Do not drive at any one constant speed, fast or
slow, for the rst 500 miles (805 km). Do not
make full-throttle starts. Avoid downshifting to
brake or slow the vehicle.
Avoid making hard stops for the rst 200 miles
(322 km) or so. During this time the new brake
linings are not yet broken in. Hard stops with
new linings can mean premature wear and
earlier replacement. Follow this breaking-in
guideline every time you get new brake linings.
Do not tow a trailer during break-in. SeeTowing
a Trailer on page 4-53for the trailer towing
capabilities of the vehicle and more information.
Following break-in, engine speed and load can
be gradually increased.
Ignition Positions
The ignition switch has
four different positions.
To shift out of P (Park), the ignition must be in ON/RUN
or ACC/ACCESSORY and the regular brake pedal
must be applied.
A (LOCK/OFF):This position locks the ignition. It also
locks the transmission on automatic transmission
vehicles. The key can be removed in LOCK/OFF.
On vehicles with an automatic transmission, the shift
lever must be in P (Park) to turn the ignition switch
to LOCK/OFF.
2-22

See “Range Selection Mode” later in this section.
P (Park):This position locks the rear wheels. It is the
best position to use when starting the engine because
the vehicle cannot move easily. 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 P (Park).
See Torque Lock (Automatic Transmission) under
Shifting Into Park on page 2-52for more information.
{CAUTION:
It is dangerous to get out of the vehicle if the shift
lever is not fully in P (Park) with the parking brake
rmly set. The vehicle can roll.
CAUTION: (Continued)
CAUTION: (Continued)
Do not leave the 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 the
vehicle will not move, even when you are on fairly
level ground, always set the parking brake and
move the shift lever to P (Park). SeeShifting Into
Park on page 2-52. If you are pulling a trailer,
seeTowing a Trailer on page 4-53.
{CAUTION:
If you have Four-Wheel Drive, the vehicle will
be free to roll — even if the shift lever is in
P (Park) — if the 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 on page 2-52. Heavy Duty 6-Speed Automatic Transmission
Shown (Light Duty 6 Speed Similar)
2-29

R (Reverse):Use this gear to back up.
Notice:Shifting to R (Reverse) while the vehicle is
moving forward could damage the transmission.
The repairs would not be covered by the vehicle
warranty. Shift to R (Reverse) only after the vehicle
is stopped.
To rock the vehicle back and forth to get out of snow, ice,
or sand without damaging the transmission, seeIf Your
Vehicle is Stuck in Sand, Mud, Ice, or Snow on
page 4-32.
N (Neutral):In this position, the engine does not
connect with the wheels. To restart when you are
already moving, use N (Neutral) only. Also, use
N (Neutral) when the vehicle is being towed.
{CAUTION:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is rmly on the brake pedal, the vehicle could
move very rapidly. You could lose control and hit
people or objects. Do not shift into a drive gear
while the engine is running at high speed.Notice:Shifting out of P (Park) or N (Neutral) with
the engine running at high speed may damage
the transmission. The repairs would not be covered
by the vehicle warranty. Be sure the engine is
not running at high speed when shifting the vehicle.
D (Drive):This position is for normal driving. It provides
the best fuel economy. If you need more power for
passing, and you are:
Going less than about 35 mph (55 km/h), push the
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.
D (Drive) 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 4-11.
2-30

The vehicle has 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 is
able to maintain vehicle speed by analyzing things such
as vehicle speed, throttle position, and vehicle load.
If the shift stabilization feature determines that a current
vehicle speed cannot be maintained, the transmission
does not upshift and instead holds the current gear.
In some cases, this could appear to be a delayed shift,
however the transmission is operating normally.
The transmission uses adaptive shift controls.
Adaptive shift controls continually compares key shift
parameters to pre-programmed ideal shifts stored in the
transmissions computer. The transmission constantly
makes adjustments to improve vehicle performance
according to how the vehicle is being used, such as with
a heavy load or when temperature changes. During this
adaptive shift control process, shifting might feel different
as the transmission determines the best settings.
When temperatures are very cold, the Allison
Transmission
®and Hydra-Matic®6-Speed
transmission’s gear shifting could be delayed providing
more stable shifts until the engine warms up. Shifts
could be more noticeable with a cold transmission.
This difference in shifting is normal.M (Manual Mode):This position is available on
vehicles with the Allison Transmission
®or Hydra-Matic®
6-Speed transmission. It lets drivers select the range
of gears appropriate for current driving conditions.
If the vehicle has this feature, see Range Select Mode
(Allison Transmission
®or Hydra-Matic®6-Speed
transmission) later in this section.
3 (Third):This position is also used for normal driving.
It reduces vehicle speed more than D (Drive) without
using the brakes. You might choose 3 (Third) instead of
D (Drive) when driving on hilly, winding roads, when
towing a trailer, so there is less shifting between gears
and when going down a steep hill.
2 (Second):This position reduces vehicle speed even
more than 3 (Third) without using the brakes. You can
use 2 (Second) on hills. It can help control vehicle 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 2 (Second) 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 the vehicle
from a stop on slippery road surfaces.
2-31

1 (First):For the Hydra-Matic®4-Speed transmission
this position reduces vehicle speed even more than
2 (Second) 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 1 (First) 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 the 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 1 (First) it provides the
lowest gear appropriate to current road speed and
continues to downshift as the vehicle slows, eventually
downshifting to 1 (First) 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 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.
Range Selection Mode (Allison®or
Hydra-Matic®6-Speed Transmission)
The vehicle may have a Range Selection Mode.
The Range Selection Mode helps control the vehicle’s
transmission and vehicle speed while driving down hill
or towing a trailer by letting you select a desired range
of gears.
2-32

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 3-51for more
information.
Also see Tow Haul Mode underTowing a Trailer on
page 4-53for more information.
2-34

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.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 3-51for more
information.
Also see “Tow Haul Mode” underTowing a Trailer on
page 4-53for more information.
2-35

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 2-28for
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 seeTowing a Trailer on page 4-53for 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.
SeeAutomatic Transmission Operation on page 2-28.
2-36