
GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 5/3/16
232 Climate Controls
Automatic Operation
The system automatically controls
the fan speed, air delivery, air
conditioning, and recirculation in
order to heat or cool the vehicle to
the desired temperature.
When the indicator light is on, the
system is in full automatic operation.
If the air delivery mode or fan
setting is manually adjusted, the
auto indicator turns off and displays
will show the selected settings.
To place the system in
automatic mode:1. Press AUTO.
2. Set the driver and passenger temperature.
To find your comfort setting,
start with 22 °C (72 °F) and
allow the system time to
stabilize. Then adjust the
temperature as needed for best
comfort.
To improve fuel efficiency and to
cool the vehicle faster, recirculation
may be automatically selected in
warm weather. The recirculation light will not come
on when automatically controlled.
Press
@to manually select
recirculation; press it again to select
outside air.
Do not cover the solar sensor on the
top of the instrument panel near the
windshield. This sensor regulates
air temperature based on sun load.
See “Sensors” later in this section.
Manual Operation
O:Press to turn the climate control
system on or off. Outside air still
enters the vehicle, and is directed to
the floor. This direction can be
changed by pressing the air
delivery mode.
9: Turn clockwise or
counterclockwise to increase or
decrease the fan speed. Press the
knob to turn the fan off.
Press AUTO to return to automatic
operation. Driver and Passenger
Temperature Control :
The
temperature can be adjusted
separately for the driver and
passenger.
Turn the knob clockwise or
counterclockwise to increase or
decrease the driver or passenger
temperature setting.
SYNC : Press to link the passenger
temperature setting to the driver
setting. The SYNC indicator light will
turn on. When the passenger setting
is adjusted, the SYNC indicator light
is off.
The driver side or passenger side
temperature display shows the
temperature setting increasing or
decreasing.
Air Delivery Mode Control :
Press
Y,\,[, or-to change
the direction of the airflow. An
indicator light comes on in the
selected mode button.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 5/3/16
Climate Controls 233
Changing the mode cancels the
automatic operation and the system
goes into manual mode. Press
AUTO to return to automatic
operation.
Y:Air is directed to the instrument
panel outlets.
\: Air is divided between the
instrument panel and floor outlets.
Some air is directed toward the
windshield and side window outlets.
[: Air is directed to the floor
outlets, with some to the windshield,
side window outlets, and second
row floor outlets.
-: This mode clears the windows
of fog or moisture. Air is directed to
the windshield, floor outlets, and
side window vents. The system
automatically forces outside air into
the vehicle and the air conditioning
compressor will run, unless the
outside temperature is close to
freezing.
0: Press to clear the windshield
of fog or frost more quickly. Air is
directed to the windshield and the
side window vents. The air conditioning compressor also comes
on, unless the outside temperature
is below freezing.
Do not drive the vehicle until all
windows are clear.
See
Air Vents 0234.
A/C : Press to turn the air
conditioning system on or off. An
indicator light comes on to show
that the air conditioning is enabled.
If the fan is turned off, the air
conditioner will not run. The A/C
light will stay on even if the outside
temperatures are below freezing.
@: Press to turn on recirculation.
An indicator light comes on. Air is
recirculated to quickly cool the
inside of the vehicle. It can also be
used to help reduce outside air and
odors that enter the vehicle. The air
conditioning compressor also comes
on when this mode is activated.
Rear Window Defogger
The rear window defogger uses a
warming grid to remove fog from the
rear window.
K: Press to turn the rear window
defogger on or off. An indicator light
on the button comes on to show that
the rear window defogger is on.
The rear window defogger only
works when the ignition is in ON/
RUN. The defogger turns off if the
ignition is turned to ACC/
ACCESSORY or LOCK/OFF.
Caution
Using a razor blade or sharp
object to clear the inside rear
window can damage the rear
window defogger. Repairs would
not be covered by the vehicle
warranty. Do not clear the inside
rear window with sharp objects.
Heated Mirror : If equipped with
heated outside rearview mirrors,
press
Kto heat the mirrors. See
Heated Mirrors 043.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 5/3/16
234 Climate Controls
Sensors
The solar sensor, located in the
defrost grille in the middle of the
instrument panel, monitors the solar
heat. Do not cover the solar sensor
or the system will not work properly.
There is also an exterior
temperature sensor behind the front
grille. This sensor reads the outside
air temperature and helps maintain
the temperature inside the vehicle.
Any cover on the front of the vehicle
including a snow plow, could cause
a false reading in the displayed
temperature.Some vehicles may have the
exterior temperature sensor in the
passenger side mirror instead of the
front grille area.
The climate control system uses the
information from these sensors to
maintain comfort settings by
adjusting the outlet temperature, fan
speed, and the air delivery mode.
The system may also supply cooler
air to the side of the vehicle facing
the sun. The recirculation mode will
also be used as needed to maintain
cool outlet temperatures.
Air Vents
Use the air vents in the center and
on the side of the instrument panel
to direct airflow. Use the
thumbwheels near the air vents to
open or close off the airflow.
Air vents blow warm air on the side
windows in cold weather. If Floor,
Defog, or Defrost modes are
selected, a small amount of air will
come from the vents close to the
window. If the airflow is shut off
using the thumbwheels, warm air
will be directed to the other
instrument panel vents. This is
normal operation.
Use the thumbwheels to turn vent
airflow on or off based on the mode
selected.
Operation Tips
.
Clear away any ice, snow,
or leaves from air inlets at the
base of the windshield that could
block the flow of air into the
vehicle.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
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Driving and Operating 237
Driving and
Operating
Driving Information
Distracted Driving . . . . . . . . . . . . 238
Defensive Driving . . . . . . . . . . . . . 239
Drunk Driving . . . . . . . . . . . . . . . . . 239
Control of a Vehicle . . . . . . . . . . . 239
Braking . . . . . . . . . . . . . . . . . . . . . . . 239
Steering . . . . . . . . . . . . . . . . . . . . . . 240
Off-Road Recovery . . . . . . . . . . . 241
Loss of Control . . . . . . . . . . . . . . . 241
Off-Road Driving . . . . . . . . . . . . . 242
Driving on Wet Roads . . . . . . . . 246
Hill and Mountain Roads . . . . . 247
Winter Driving . . . . . . . . . . . . . . . . 248
If the Vehicle Is Stuck . . . . . . . . 249
Vehicle Load Limits . . . . . . . . . . . 250
Truck-Camper LoadingInformation . . . . . . . . . . . . . . . . . . 256
Starting and Operating
New Vehicle Break-In . . . . . . . . . 258
Adjustable Throttle and BrakePedal . . . . . . . . . . . . . . . . . . . . . . . 258
Ignition Positions . . . . . . . . . . . . . 259
Starting the Engine . . . . . . . . . . . 260
Fast Idle System . . . . . . . . . . . . . 261 Retained Accessory
Power (RAP) . . . . . . . . . . . . . . . . 262
Engine Coolant Heater . . . . . . . 262
Shifting Into Park . . . . . . . . . . . . . 264
Shifting out of Park . . . . . . . . . . . 265
Parking over Things That Burn . . . . . . . . . . . . . . . . . . . 266
Active Fuel Management
®. . . . 266
Engine Exhaust
Engine Exhaust . . . . . . . . . . . . . . 266
Running the Vehicle While Parked . . . . . . . . . . . . . . . . . . . . . . 267
Automatic Transmission
Automatic Transmission . . . . . . 267
Manual Mode . . . . . . . . . . . . . . . . . 270
Tow/Haul Mode . . . . . . . . . . . . . . . 273
Drive Systems
Four-Wheel Drive . . . . . . . . . . . . . 274
Brakes
Antilock BrakeSystem (ABS) . . . . . . . . . . . . . . . 281
Parking Brake . . . . . . . . . . . . . . . . 282
Brake Assist . . . . . . . . . . . . . . . . . . 283
Hill Start Assist (HSA) . . . . . . . . 283
Ride Control Systems
Traction Control/Electronic Stability Control . . . . . . . . . . . . . 284 Hill Descent Control (HDC) . . . 286
Locking Rear Axle . . . . . . . . . . . . 286
Cruise Control
Cruise Control . . . . . . . . . . . . . . . . 287
Driver Assistance Systems
Driver Assistance Systems . . . 290
Assistance Systems for
Parking or Backing . . . . . . . . . . 291
Assistance Systems for Driving . . . . . . . . . . . . . . . . . . . . . . 293
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . . . . . . . 293
Forward Automatic Braking (FAB) . . . . . . . . . . . . . . . 295
Lane Departure Warning (LDW) (2500/3500
Series) . . . . . . . . . . . . . . . . . . . . . . 296
Lane Keep Assist (LKA) (1500 Series) . . . . . . . . . . . . . . . . . . . . . . 298
Fuel
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 300
California FuelRequirements . . . . . . . . . . . . . . . 301
Fuels in Foreign Countries . . . 301
Fuel Additives . . . . . . . . . . . . . . . . 301
E85 or FlexFuel . . . . . . . . . . . . . . 301
Filling the Tank . . . . . . . . . . . . . . . 302
Filling a Portable Fuel Container . . . . . . . . . . . . . . . . . . . 304

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
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Driving and Operating 241
.Reduce speed before entering a
curve.
. Maintain a reasonable steady
speed through the curve.
. Wait until the vehicle is out of
the curve before accelerating
gently into the straightaway.
Steering in Emergencies
.There are some situations when
steering around a problem may
be more effective than braking.
. Holding both sides of the
steering wheel allows you to turn
180 degrees without removing
a hand.
. Antilock Brake System (ABS)
allows steering while braking.
Off-Road Recovery
The vehicle's right wheels can drop
off the edge of a road onto the
shoulder while driving. Follow
these tips:
1. Ease off the accelerator and then, if there is nothing in the
way, steer the vehicle so that it
straddles the edge of the
pavement.
2. Turn the steering wheel about one-eighth of a turn, until the
right front tire contacts the
pavement edge. 3. Turn the steering wheel to go
straight down the roadway.
Loss of Control
Skidding
There are three types of skids that
correspond to the vehicle's three
control systems:
.Braking Skid —wheels are not
rolling.
. Steering or Cornering Skid —
too much speed or steering in a
curve causes tires to slip and
lose cornering force.
. Acceleration Skid —too much
throttle causes the driving
wheels to spin.
Defensive drivers avoid most skids
by taking reasonable care suited to
existing conditions, and by not
overdriving those conditions. But
skids are always possible.
If the vehicle starts to slide, follow
these suggestions:
. Ease your foot off the
accelerator pedal and steer the
way you want the vehicle to go.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 5/3/16
242 Driving and Operating
The vehicle may straighten out.
Be ready for a second skid if it
occurs.
. Slow down and adjust your
driving according to weather
conditions. Stopping distance
can be longer and vehicle
control can be affected when
traction is reduced by water,
snow, ice, gravel, or other
material on the road. Learn to
recognize warning clues —such
as enough water, ice, or packed
snow on the road to make a
mirrored surface —and slow
down when you have any doubt.
. Try to avoid sudden steering,
acceleration, or braking,
including reducing vehicle speed
by shifting to a lower gear. Any
sudden changes could cause
the tires to slide.
Remember: Antilock brakes help
avoid only the braking skid.
Off-Road Driving
Four-wheel-drive vehicles can be
used for off-road driving. Vehicles
without four-wheel drive and vehicles not equipped with All
Terrain (AT) or On-Off Road (OOR)
tires must not be driven off-road
except on a level, solid surface. For
contact information about the
original equipment tires, see the
warranty manual.
One of the best ways for successful
off-road driving is to control the
speed.
{Warning
When driving off-road, bouncing
and quick changes in direction
can easily throw you out of
position. This could cause you to
lose control and crash. You and
your passengers should always
wear safety belts.
Before Driving Off-Road
.
Have all necessary maintenance
and service work completed.
. Fuel the vehicle, fill fluid levels,
and check inflation pressure in
all tires, including the spare,
if equipped. .
Read all the information about
four-wheel-drive vehicles in this
manual.
. Remove any underbody air
deflector, if equipped. Re-attach
the air deflector after off-road
driving.
. See Hill Descent Control
(HDC) 0286
. Know the local laws that apply to
off-road driving.
To gain more ground clearance if
needed, it may be necessary to
remove the front fascia lower air
dam. However, driving without the
air dam reduces fuel economy.
Caution
Operating the vehicle for
extended periods without the front
fascia lower air dam installed can
cause improper airflow to the
engine. Reattach the front fascia
air dam after off-road driving.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 5/3/16
248 Driving and Operating
Warning (Continued)
loss of steering. Always have the
engine running and the vehicle
in gear.
. Drive at speeds that keep the
vehicle in its own lane. Do not
swing wide or cross the
center line.
. Be alert on top of hills;
something could be in your lane
(e.g., stalled car, accident).
. Pay attention to special road
signs (e.g., falling rocks area,
winding roads, long grades,
passing or no-passing zones)
and take appropriate action.
Winter Driving
Driving on Snow or Ice
Snow or ice between the tires and
the road creates less traction or
grip, so drive carefully. Wet ice can
occur at about 0 °C (32 °F) when freezing rain begins to fall. Avoid
driving on wet ice or in freezing rain
until roads can be treated.
For Slippery Road Driving:
.
Accelerate gently. Accelerating
too quickly causes the wheels to
spin and makes the surface
under the tires slick.
. Turn on Traction Control. See
Traction Control/Electronic
Stability Control 0284.
. The Antilock Brake System
(ABS) improves vehicle stability
during hard stops, but the
brakes should be applied sooner
than when on dry pavement.
See Antilock Brake System
(ABS) 0281.
. Allow greater following distance
and watch for slippery spots. Icy
patches can occur on otherwise
clear roads in shaded areas.
The surface of a curve or an
overpass can remain icy when
the surrounding roads are clear.
Avoid sudden steering
maneuvers and braking while
on ice. .
Turn off cruise control.
Blizzard Conditions
Stop the vehicle in a safe place and
signal for help. Stay with the vehicle
unless there is help nearby.
If possible, use Roadside
Assistance. See Roadside
Assistance Program 0461. To get
help and keep everyone in the
vehicle safe:
. Turn on the hazard warning
flashers.
. Tie a red cloth to an outside
mirror.
{Warning
Snow can trap engine exhaust
under the vehicle. This may
cause exhaust gases to get
inside. Engine exhaust contains
carbon monoxide (CO), which
cannot be seen or smelled. It can
cause unconsciousness and even
death.
If the vehicle is stuck in snow:
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
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Driving and Operating 249
Warning (Continued)
.Clear snow from the base of
the vehicle, especially any
blocking the exhaust pipe.
. Open a window about 5 cm
(2 in) on the vehicle side
that is away from the wind,
to bring in fresh air.
. Fully open the air outlets on
or under the instrument
panel.
. Adjust the climate control
system to circulate the air
inside the vehicle and set
the fan speed to the highest
setting. See “Climate
Control Systems.”
For more information about CO,
see Engine Exhaust 0266.
To save fuel, run the engine for
short periods to warm the vehicle
and then shut the engine off and
partially close the window. Moving
about to keep warm also helps. If it takes time for help to arrive,
when running the engine, push the
accelerator pedal slightly so the
engine runs faster than the idle
speed. This keeps the battery
charged to restart the vehicle and to
signal for help with the headlamps.
Do this as little as possible, to
save fuel.
If the Vehicle Is Stuck
Slowly and cautiously spin the
wheels to free the vehicle when
stuck in sand, mud, ice, or snow.
See
“Rocking the Vehicle to Get It
Out” later in this section.
The Traction Control System (TCS)
can often help to free a stuck
vehicle. See Traction Control/
Electronic Stability Control 0284.
If TCS cannot free the vehicle, see
“Rocking the Vehicle to Get it Out”
following.
{Warning
If the vehicle's tires spin at high
speed, they can explode, and you
or others could be injured. The
vehicle can overheat, causing an
engine compartment fire or other
damage. Spin the wheels as little
as possible and avoid going
above 56 km/h (35 mph).
For information about using tire
chains on the vehicle, see Tire
Chains 0405.
Rocking the Vehicle to Get
It Out
Turn the steering wheel left and
right to clear the area around the
front wheels. For four-wheel-drive
vehicles, shift into Four-Wheel Drive
High. Turn the TCS off. Shift back
and forth between R (Reverse) and
a forward gear, spinning the wheels
as little as possible. To prevent
transmission wear, wait until the
wheels stop spinning before shifting
gears. Slowly spinning the wheels in
the forward and reverse directions