
Black plate (52,1)GMC Sierra Owner Manual - 2011
9-52 Driving and Operating
Tow/Haul Mode
(Allison Transmission
or Hydra-Matic 6-Speed
Automatic Transmission)
Vehicles with an Allison
Transmission 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.
See
Tow/Haul Mode Light on
page 5‑29 for more information.
Also see “Tow/Haul Mode” under
Towing Equipment on page 9‑112
for 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 Manual Mode on
page 9‑50 for more information
on the Range Selection Mode.

Black plate (71,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-71
When the vehicle is started
and begins to move, the system
performs several diagnostic checks
to insure there are no problems.
The system may be heard or
felt while it is working. This is
normal and does not mean there
is a problem with the vehicle.
The system should initialize
before the vehicle reaches 32 km/h
(20 mph). In some cases, it may
take approximately 3.2 km (2 mi) of
driving before the system initializes.
If cruise control is being used when
StabiliTrak activates, the cruise
control automatically disengages.
The cruise control can be
re-engaged when road conditions
allow. SeeCruise Control on
page 9‑73 for more information.
If the system fails to turn on or
activate, the StabiliTrak light
along with one of the following
messages will be displayed
on the Driver Information
Center (DIC): TRACTION CONTROL OFF, SERVICE
TRACTION CONTROL,
STABILITRAK OFF, SERVICE
STABILITRAK. If these DIC
messages appear, make sure the
StabiliTrak system has not been
turned off using the StabiliTrak
on/off button. Then turn the vehicle
off, wait 15 seconds, and turn it
back on again to reset the system.
If any of these messages still
appear on the DIC, the vehicle
should be taken in for service.
For more information on the DIC
messages, see
Ride Control
System Messages on page 5‑47.
The StabiliTrak light will flash on the
instrument panel cluster when the
system is both on and activated. The system may be heard or felt
while it is working; this is normal.
The traction control disable button
is located on the instrument panel
below the climate controls.
The Traction Control System (TCS)
part of StabiliTrak can be turned
off by pressing and releasing the
StabiliTrak button. To disable both
TCS and StabiliTrak, press and
hold
5untilFilluminates and the
appropriate DIC message displays.
TCS and StabiliTrak can be turned
on by pressing and releasing the
StabiliTrak button if they are not
automatically shut off for any other
reason.

Black plate (74,1)GMC Sierra Owner Manual - 2011
9-74 Driving and Operating
When the brakes are applied, cruise
control is turned off.
For vehicles with an Allison or
Hydra‐Matic 6‐speed automatic
transmission, see“Grade Braking
and Cruise Grade Braking
(Allison Transmission) under
Tow/Haul Mode on page 9‑51
for an explanation of how cruise
control interacts with the Range
Selection Mode, tow/haul and
grade braking systems.
For vehicles with the StabiliTrak
system that begins to limit wheel
spin while you are using cruise
control, the cruise control will
automatically disengage. See
StabiliTrak
®System on page 9‑70.
When road conditions allow the
cruise control to be safely used
again, it can be turned back on.
The cruise control buttons are
located on the left side of the
steering wheel.
I(On/Off): Press to turn the
system on or off. The indicator light
is on when cruise control is on and
turns off when cruise control is off.
+ RES (Resume/Accelerate):
Press briefly to resume to a
previously set speed, or press
and hold to accelerate.
SET −(Set/Coast): Press to set
the speed and activate cruise
control or make the vehicle
decelerate.
[(Cancel): Press to disengage
cruise control without erasing the
set speed from memory.
Setting Cruise Control
If the cruise button is on when not in
use, it could get bumped and go into
cruise when not desired. Keep the
cruise control switch off when cruise
is not being used.
The cruise control light on the
instrument panel cluster will come
on after the cruise control has been
set to the desired speed.
1. Press
I.
2. Get up to the desired speed.
3. Press the SET− button located
on the steering wheel and
release it.
4. Take your foot off the accelerator.

Black plate (84,1)GMC Sierra Owner Manual - 2011
9-84 Driving and Operating
Fuel
For diesel engine vehicles, see
“Fuel for Diesel Engines”in the
Duramax Diesel Supplement.
For Vehicles with gasoline engines,
please read this.
Gasoline
Use of the recommended fuel
is an important part of the proper
maintenance of this vehicle. To help
keep the engine clean and maintain
optimum vehicle performance, we
recommend the use of gasoline
advertised as TOP TIER Detergent
Gasoline.
Look for the TOP TIER label on the
fuel pump to ensure gasoline meets
enhanced detergency standards
developed by auto companies. A list
of marketers providing TOP TIER
Detergent Gasoline can be found
at www.toptiergas.com.
The eighth digit of the Vehicle
Identification Number (VIN) shows
the code letter or number that
identifies the vehicle's engine.
The VIN is at the top left of the
instrument panel. See Vehicle
Identification Number (VIN) on
page 12‑1.
Vehicles that have a FlexFuel badge
and a yellow fuel cap can use either
unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85). See
Fuel E85 (85% Ethanol) on
page 9‑87. For all other vehicles,
use only the unleaded gasoline
described under Recommended
Fuel on page 9‑84.
Recommended Fuel
For all vehicles except those with
the 6.2L V8 engine (VIN Code 2),
use regular unleaded gasoline
with a posted octane rating of 87 or
higher. If the octane rating is less
than 87, an audible knocking noise,
commonly referred to as spark
knock, might be heard when driving.
If this occurs, use a gasoline rated
at 87 octane or higher as soon
as possible. If heavy knocking is
heard when using gasoline rated
at 87 octane or higher, the engine
needs service.

Black plate (92,1)GMC Sierra Owner Manual - 2011
9-92 Driving and Operating
Driving with a Trailer
{WARNING
When towing a trailer, exhaust
gases may collect at the rear
of the vehicle and enter if the
liftgate, trunk/hatch, or rear-most
window is open.
Engine exhaust contains Carbon
Monoxide (CO) which cannot be
seen or smelled. It can cause
unconsciousness and even death.
To maximize safety when towing
a trailer:
.Have the exhaust system
inspected for leaks and make
necessary repairs before
starting a trip.
.Never drive with the liftgate,
trunk/hatch, or rear-most
window open.(Continued)
WARNING (Continued)
.Fully open the air outlets
on or under the instrument
panel.
.Adjust the Climate Control
system to a setting that
brings in only outside air
and set the fan speed to the
highest setting. See Climate
Control System in the Index.
For more information about
Carbon Monoxide, see Engine
Exhaust on page 9‑44.
Towing a trailer requires a
certain amount of experience.
The combination you are driving is
longer and not as responsive as the
vehicle itself. Get acquainted with
the handling and braking of the rig
before setting out for the open road. Before starting, check all trailer
hitch parts and attachments, safety
chains, electrical connectors,
lamps, tires, and mirrors. If the
trailer has electric brakes, start the
combination moving and then apply
the trailer brake controller by hand
to be sure the brakes work.
During the trip, check occasionally
to be sure that the load is secure
and the lamps and any trailer
brakes still work.
Following Distance
Stay at least twice as far behind the
vehicle ahead as you would when
driving the vehicle without a trailer.
This can help to avoid heavy
braking and sudden turns.

Black plate (93,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-93
Passing
More passing distance is
needed when towing a trailer.
The combination will not accelerate
as quickly and is longer so it is
necessary to go much farther
beyond the passed vehicle before
returning to the lane.
Backing Up
Hold the bottom of the steering
wheel with one hand. To move the
trailer to the left, move that hand
to the left. To move the trailer to
the right, move your hand to the
right. Always back up slowly and,
if possible, have someone
guide you.
Making Turns
Notice:Making very sharp turns
while trailering could cause the
trailer to come in contact with
the vehicle. The vehicle could be
damaged. Avoid making very
sharp turns while trailering.
When turning with a trailer,
make wider turns than normal.
Do this so the trailer will not strike
soft shoulders, curbs, road signs,
trees, or other objects. Avoid jerky
or sudden maneuvers. Signal well
in advance.
If the trailer turn signal bulbs burn
out, the arrows on the instrument
panel will still flash for turns. It is
important to check occasionally to
be sure the trailer bulbs are still
working.
Driving on Grades
Reduce speed and shift to a
lower gear beforestarting down
a long or steep downgrade. If the
transmission is not shifted down,
the brakes might get hot and no
longer work well.
Vehicles can tow in D (Drive).
Shift the transmission to a lower
gear if the transmission shifts too
often under heavy loads and/or
hilly conditions.
The Tow/Haul Mode may be used
if the transmission shifts too often.
See Tow/Haul Mode on page 9‑51.
When towing at high altitude on
steep uphill grades, consider the
following: Engine coolant will boil
at a lower temperature than at
normal altitudes. If the engine is
turned off immediately after towing
at high altitude on steep uphill
grades, the vehicle may show
signs similar to engine overheating.

Black plate (116,1)GMC Sierra Owner Manual - 2011
9-116 Driving and Operating
Camper/Fifth-Wheel Trailer Wiring
Package
The seven-wire camper harness
is located under the front edge of
the pickup box on the driver side
of the vehicle, attached to the
frame bracket. A connector must
be added to the wiring harness
which connects to the camper.
The harness contains the following
camper/trailer circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn
Signal
.Brown: Taillamps
.White: Ground
.Light Green: Back-up Lamps
.Red: Battery Feed
.Dark Blue: Trailer Brake
If the vehicle is equipped with the
“Heavy-Duty Trailering”option,
please refer to “Heavy-Duty Trailer
Wiring Package” earlier in this
section.
When the camper-wiring harness
is ordered without the heavy-duty
trailering package, an eight-wire
harness with a seven-pin connector
is located at the rear of the vehicle
and is tied to the vehicle's frame.
Electric Brake Control Wiring
Provisions
These wiring provisions are
included with the vehicle as part
of the trailer wiring package. These
provisions are for an electric brake
controller. The instrument panel
contains blunt cut wires behind the
steering column for the trailer brake
controller. The harness contains the
following wires:
.Dark Blue: Brake Signal to
Trailer Connector
.Red/Black: Battery
.Light Blue/White: Brake Switch
.White: Ground
The harness should be installed by
your dealer or a qualified service
center.

Black plate (117,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-117
If the vehicle is equipped with an
Integrated Trailer Brake Control
(ITBC) System, the blunt cuts
exist, but are not connected further
in the harness. If an aftermarket
trailer brake controller is installed,
the ITBC must be disconnected.
Do not power both ITBC and
aftermarket controllers to control
the trailer brakes at the same time.
Tow/Haul Mode
Pressing this button at the end of
the shift lever turns on and off the
Tow/Haul Mode.
This indicator light on the instrument
panel cluster comes on when the
Tow/Haul Mode is on.
Tow/Haul is a feature that assists
when pulling a heavy trailer or a
large or heavy load. SeeTow/Haul
Mode on page 9‑51 for more
information.
Tow/Haul is designed to be most
effective when the vehicle and
trailer combined weight is at least
75 percent of the vehicle's Gross
Combined Weight Rating (GCWR).
See “Weight of the Trailer” under
Trailer Towing on page 9‑95.
Tow/Haul is most useful under
the following driving conditions:
.When pulling a heavy trailer or
a large or heavy load through
rolling terrain.
.When pulling a heavy trailer
or a large or heavy load in
stop-and-go traffic.
.When pulling a heavy trailer
or a large or heavy load in busy
parking lots where improved low
speed control of the vehicle is
desired.
Operating the vehicle in Tow/Haul
when lightly loaded or with no
trailer at all will not cause damage.
However, there is no benefit to
the selection of Tow/Haul when
the vehicle is unloaded. Such a
selection when unloaded may
result in unpleasant engine and
transmission driving characteristics
and reduced fuel economy. Tow/
Haul is recommended only when
pulling a heavy trailer or a large
or heavy load.