
Black plate (25,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-25
Do not turn the engine off when the
vehicle is moving. This will cause a
loss of power assist in the brake
and steering systems and disable
the airbags.
If the vehicle must be shut off in an
emergency:
1. Brake using a firm and steadypressure. Do not pump the
brakes repeatedly. This may
deplete power assist, requiring
increased brake pedal force.
2. Shift the vehicle to N (Neutral). This can be done while the
vehicle is moving. After shifting
to N (Neutral), firmly apply the
brakes and steer the vehicle to a
safe location.
3. Come to a complete stop, shift to P (Park), and turn the ignition
to LOCK/OFF. On vehicles with
an automatic transmission, the
shift lever must be in P (Park) to
turn the ignition switch to the
LOCK/OFF position. 4. Set the parking brake. See
Parking Brake on page 9-47.
{Warning
Turning off the vehicle while
moving may cause loss of power
assist in the brake and steering
systems and disable the airbags.
While driving, only shut the
vehicle off in an emergency.
If the vehicle cannot be pulled over,
and must be shut off while driving,
turn the ignition to ACC/
ACCESSORY.
{Caution
Using a tool to force the key to
turn in the ignition could cause
damage to the switch or break the
key. Use the correct key, make
sure it is all the way in, and turn it
only with your hand. If the key
cannot be turned by hand, see
your dealer. 2 (ACC/ACCESSORY):
This
position lets things like the radio
and the windshield wipers operate
while the engine is off. It also
unlocks the steering wheel. Use this
position if the vehicle must be
pushed or towed.
3 (ON/RUN): This position can be
used to operate the electrical
accessories and to display some
instrument cluster warning and
indicator lights. This position can
also be used for service and
diagnostics, and to verify the proper
operation of the malfunction
indicator lamp as may be required
for emission inspection purposes.
The switch stays in this position
when the engine is running. The
transmission is also unlocked in this
position on automatic transmission
vehicles.
If the key is left in the ACC/
ACCESSORY or ON/RUN position
with the engine off, the battery could
be drained. The vehicle may not
start if the battery is allowed to drain
for an extended period of time.

Black plate (40,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-40 Driving and Operating
Drive Systems
Four-Wheel Drive
If equipped, four-wheel drive
engages the front axle for extra
traction. Read the appropriate
section for transfer case operation
before using.
{Caution
Driving on clean, dry pavement in
four-wheel drive for an extended
period of time may cause
premature wear on the system.
The damage would not be
covered by the vehicle warranty.
Driving on clean, dry pavement in
four-wheel drive may:
.Cause a vibration to be felt in
the steering system.
.Cause tires to wear faster.
.Make the transfer case harder to
shift, and cause it to run noisier.
{Warning
Shifting the transfer case to
N (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
N (Neutral). See Parking Brake on
page 9-47.
{Caution
Extended high-speed operation in
4
nmay damage or shorten the
life of the drivetrain.
Engagement noise and bump when
shifting between 4
nand 4mor from
N (Neutral), with the engine running,
is normal. Shifting into 4
nwill turn Traction
Control and StabiliTrak®off. See
Traction Control/Electronic Stability
Control on page 9-49.
Electronic Transfer Case
Use the transfer case knob, next to
the steering wheel, to shift into and
out of four-wheel drive for extra
traction.
Indicator lights on the knob show
which setting the transfer case is in.
The N (Neutral) indicator is on the
face of the knob. The indicator lights
display briefly when the ignition is

Black plate (41,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-41
turned on, and one will stay on.
If the lights display momentarily
when the ignition is in ON/RUN, but
none stay on, the knob may have
been turned while the vehicle was
off. To see the indicator, turn the
knob to another position so that it
matches the actual transfer case
setting. If no lights display, take the
vehicle to your dealer for service.
An indicator light flashes while
shifting and until the shift is
complete.
If the transfer case cannot complete
a requested shift, it will return to the
last chosen setting. Turn the control
back to the previous setting to see
the indicator light.
{Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.The settings are:
N (Neutral):
Shift the transfer case
to N (Neutral) only when towing the
vehicle. See Recreational Vehicle
Towing on page 10-91 orTowing the
Vehicle on page 10-91.
2
m(Two-Wheel Drive High): Use
for driving on most streets and
highways. The front axle is not
engaged. This setting provides the
best fuel economy.
4
n(Four-Wheel Drive Low): This
setting engages the front axle and
delivers extra torque. Choose 4
nif
driving off-road in deep sand, deep
mud, or deep snow, and while
climbing or descending steep hills.
When engaged, keep vehicle speed
below 72 km/h (45 mph).
Shifting into 4
nwill turn Traction
Control and StabiliTrak off. See
Traction Control/Electronic Stability
Control on page 9-49. 4
m(Four-Wheel Drive High):
Use
when extra traction is needed. The
front axle engages and helps when
driving on snowy or icy roads, when
off-roading, or when plowing snow.
The vehicle can be shifted from 2
m
to 4mwhile the vehicle is moving.
Shifting Into 4
m
Turn the knob to 4mat any speed
up to 121 km/h (75 mph), except
from 4
n. The indicator light will flash
while shifting and will remain on the
selected setting.
Shifting Into 2
m
Turn the knob to 2mat any speed,
except when shifting from 4
n.

Black plate (43,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-43
8. Turn the engine off, and theignition to ACC/ACCESSORY.
9. Place the transmission shift lever in P (Park).
10. See Recreational Vehicle
Towing on page 10-91.
11. Turn the ignition to LOCK/OFF.
Shifting Out of N (Neutral)
To shift out of N (Neutral):
1. Set the parking brake and apply the brake pedal.
2. Turn the ignition to ON/RUN with the engine off.
3. Shift the transmission to N (Neutral).
4. Turn the transfer case knob to 2
m.
After the transfer case has
shifted out of N (Neutral), the
N (Neutral) light will go out.
5. Release the parking brake.
{Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
6. Start the engine and shift the transmission to the desired gear.
Automatic Transfer Case
Use the transfer case knob next to
the steering wheel to shift into and
out of four-wheel drive.
Indicator lights display which setting
the transfer case is in. N (Neutral) is
indicated on the face of the knob.
The indicator lights will display
briefly when the ignition is turned on
and one will stay on. If the lights
display momentarily when the
ignition is in ON/RUN, but none stay
on, the knob may have been turned
while the vehicle was off. To see the
indicator, turn the knob to another
position so that it matches the
actual transfer case setting. If no
lights display, take the vehicle to
your dealer for service. An indicator
light flashes while shifting the
transfer case and remains
illuminated when the shift is
complete.
If the transfer case cannot make a
requested shift, it will return to the
last chosen setting. Turn the knob
back to the previous transfer case
setting to see the indicator.

Black plate (59,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-59
Assistance Systems for
Driving
If equipped, when driving the
vehicle, Forward Collision Alert
(FCA) and Lane Departure Warning
(LDW) can help to avoid a crash or
reduce crash damage.
Forward Collision Alert
(FCA) System
If equipped, the FCA system may
help to avoid or reduce the harm
caused by front-end crashes. When
approaching a vehicle ahead too
quickly, FCA provides a red flashing
alert on the windshield and rapidly
beeps or pulses the driver seat.
FCA also lights an amber visual
alert if following another vehicle
much too closely.
FCA detects vehicles within a
distance of approximately 60 m
(197 ft) and operates at speeds
above 40 km/h (25 mph).
{Warning
FCA is a warning system and
does not apply the brakes. When
approaching a slower-moving or
stopped vehicle ahead too rapidly,
or when following a vehicle too
closely, FCA may not provide a
warning with enough time to help
avoid a crash. FCA does not warn
of pedestrians, animals, signs,
guardrails, bridges, construction
barrels, or other objects. Be ready
to take action and apply the
brakes. For more information, see
Defensive Driving on page 9-3.
FCA can be disabled with the FCA
steering wheel control.
Detecting the Vehicle Ahead
FCA warnings will not occur unless
the FCA system detects a vehicle
ahead. When a vehicle is detected
ahead, the vehicle-ahead indicator
will display green. Vehicles may not
be detected on curves, highway exit
ramps, or hills; or due to poor
visibility. FCA will not detect another
vehicle ahead until it is completely
in the driving lane.
{Warning
FCA does not provide a warning
to help avoid a crash, unless it
detects a vehicle. FCA may not
detect a vehicle ahead if the FCA
sensor is blocked by dirt, snow, (Continued)

Black plate (9,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Service and Maintenance 11-9
Additional
Maintenance and Care
Your vehicle is an important
investment and caring for it properly
may help to avoid future costly
repairs. To maintain vehicle
performance, additional
maintenance services may be
required.
It is recommended that your dealer
perform these services—their
trained dealer technicians know
your vehicle best. Your dealer can
also perform a thorough
assessment with a multi-point
inspection to recommend when your
vehicle may need attention.
The following list is intended to
explain the services and conditions
to look for that may indicate
services are required. Battery
The battery supplies power to start
the engine and operate any
additional electrical accessories.
.To avoid break-down or failure to
start the vehicle, maintain a
battery with full cranking power.
.Trained dealer technicians have
the diagnostic equipment to test
the battery and ensure that the
connections and cables are
corrosion-free.
Belts
.Belts may need replacing if they
squeak or show signs of
cracking or splitting.
.Trained dealer technicians have
access to tools and equipment
to inspect the belts and
recommend adjustment or
replacement when necessary. Brakes
Brakes stop the vehicle and are
crucial to safe driving.
.Signs of brake wear may include
chirping, grinding, or squealing
noises, or difficulty stopping.
.Trained dealer technicians have
access to tools and equipment
to inspect the brakes and
recommend quality parts
engineered for the vehicle.
Fluids
Proper fluid levels and approved
fluids protect the vehicle’s systems
and components. See
Recommended Fluids and
Lubricants on page 11-12 for GM
approved fluids.
.Engine oil and windshield
washer fluid levels should be
checked at every fuel fill.
.Instrument cluster lights may
come on to indicate that fluids
may be low and need to be
filled.

Black plate (4,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
14-4 OnStar
navigation system in the vehicle (if
equipped). After the call ends, press
the“Go” button on the navigation
screen to begin driving directions.
If directions are downloaded to the
navigation system, the route can
only be canceled through the
navigation system.
Destinations can also be
downloaded on the go. For
information about eNav or
Destination Download, see
www.onstar.com (U.S.) or
www.onstar.ca (Canada).
Connections
The required specific Onstar
subscription plan includes the
services that follow to help
customers stay connected.
For coverage maps, see
www.onstar.com (U.S.) or
www.onstar.ca (Canada). WiFi Connectivity (If Equipped)
The vehicle has a WiFi hotspot that
provides a high-speed, wireless
Internet connection to connect
multiple mobile devices (data plan
required).
1. To retrieve WiFi hotspot
information, press
=and select
or say “WiFi settings.”
2. The WiFi settings will display the WiFi network name/SSID,
passphrase, and level of
encryption.
3. To change the SSID or passphrase, press
Qor call
1-888-4-ONSTAR to connect
with an Advisor.
OnStar RemoteLink
®Mobile App
(If Equipped)
Download the OnStar RemoteLink
mobile app to select Apple
®,
Android™, and BlackBerry®or
Windows 7 or 8 mobile devices.
From the mobile device, check the
vehicle’s fuel level, oil life, or tire pressure (if the vehicle is equipped
with the tire pressure monitoring
system); or activate remote horn
and lights. Also remote start the
vehicle (if factory equipped) or
unlock the doors from anywhere
with a wireless connection (if
equipped with automatic locks).
With a required specific OnStar
subscription plan, a destination can
be sent to the vehicle. For OnStar
RemoteLink information and
compatibility, see www.onstar.com
(U.S.) or www.onstar.ca (Canada).
OnStar RemoteLink
®Key Fob
Services
This feature is included for five
years and allows for remote door
lock/unlock (if equipped with
automatic locks), remote start (if
factory equipped), or activation of
horn and lights from anywhere with
a wireless signal. Download the app
and start using it any time during the
trial period to get started.

Black plate (5,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
INDEX i-5
FlexFuelE85 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-65
Floor Console Storage . . . . . . . . . . 4-3
Floor Mats . . . . . . . . . . . . . . . . . . .10-105
Fluid AutomaticTransmission . . . . . . . 10-12, 10-15
Brakes . . . . . . . . . . . . . . . . . . . . . . 10-27
Four-Wheel Drive Transfer Case . . . . . . . . . . . . . . . 9-40
Power Steering . . . . . . . . . . . . . 10-24
Washer . . . . . . . . . . . . . . . . . . . . . 10-25
Fog Lamps . . . . . . . . . . . . . . . . . . . . . 6-5 Bulb Replacement . . . . . . . . . . 10-37
Folding Mirrors . . . . . . . . . . . . . . . . 2-16
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . 9-59
Four-Wheel Drive . . . . . . . 9-40, 10-29
Four-Wheel-Drive Light . . . . . . . . 5-22
Frequency Statement Radio . . . . . . . . . . . . . . . . . . . . . . . 13-12
Front Axle . . . . . . . . . . . . . . . . . . . . 10-30 Front Fog Lamp
Light . . . . . . . . . . . . . . . . . . . . . . . . . . 5-26
Front Seats Heated and Cooled . . . . . . . . . . . . 3-7
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-63 Additives . . . . . . . . . . . . . . . . . . . . . 9-64
Economy Driving . . . . . . . . . . . . . 1-21
Filling a Portable FuelContainer . . . . . . . . . . . . . . . . . . . 9-67
Filling the Tank . . . . . . . . . . . . . . . 9-66
Foreign Countries . . . . . . . . . . . . 9-64
Gauge . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Low Fuel Warning Light . . . . . . . 5-25
Management, Active . . . . . . . . . . 9-32
Requirements, California . . . . . 9-64
System Messages . . . . . . . . . . . . 5-35
Full-Size Spare Tire . . . . . . . . . . 10-86
Fuses . . . . . . . . . . . . . . . . . . . . . . . . 10-41 Engine CompartmentFuse Block . . . . . . . . . . . . . . . . 10-41
Instrument Panel
Fuse Block . . . . . . . . . 10-45, 10-48G
Garage Door Opener . . . . . . . . . . 5-49Programming . . . . . . . . . . . . . . . . . 5-49
Gauges Engine CoolantTemperature . . . . . . . . . . . . . . . . 5-13
Engine Oil Pressure . . . . . . . . . . 5-12
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Odometer . . . . . . . . . . . . . . . . . . . . . 5-11
Speedometer . . . . . . . . . . . . . . . . . 5-11
Tachometer . . . . . . . . . . . . . . . . . . . 5-11
Transmission Temperature . . . . 5-14
Trip Odometer . . . . . . . . . . . . . . . . 5-11
Voltmeter . . . . . . . . . . . . . . . . . . . . . 5-15
Warning Lights and Indicators . . . . . . . . . . . . . . . . . . . . 5-8
General Information Service and Maintenance . . . . . 11-1
Towing . . . . . . . . . . . . . . . . . . . . . . . . 9-68
Vehicle Care . . . . . . . . . . . . . . . . . . 10-2
Glass Replacement . . . . . . . . . . . 10-35
Glove Box . . . . . . . . . . . . . . . . . . . . . . 4-1
GM Mobility Reimbursement Program . . . . . . . . . . . . . . . . . . . . . . 13-5