
Black plate (58,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-58 Driving and Operating
The instrument cluster may have a
parking assist display with bars that
show “ distance to object ” and object
location information for RPA, and on
some vehicles, for FPA. As the
object gets closer, more bars light
up and the bars change color from
yellow to amber to red.
When an object is first detected in
the rear, one beep will be heard
from the rear, or both sides of the
Safety Alert Seat will pulse two
times. When an object is very close
(<0.6 m (2 ft) in the vehicle rear,
or <0.3 m (1 ft) in the vehicle front),
a continuous beep will sound from the front or rear, or both sides of the
Safety Alert Seat will pulse five
times. Beeps for FPA are higher
pitched than for RPA.
Turning the Features On or Off
The
X button on the center stack
is used to turn on or off the Front
and Rear Parking Assist. The
indicator light in the button comes
on when the features are on and
turns off when the features have
been disabled.
Front and Rear Parking Assist can
be turned off, on, or on with towbar
through vehicle personalization. See
“ Park Assist ” under Vehicle
Personalization on page 5-42 . If the
parking assist is turned off through
vehicle personalization, the parking
assist button on the center stack will be disabled. To turn the parking
assist on again, select On in the
vehicle personalization menu. The
On with Towbar setting allows for
the parking assist to work properly
with a small item attached to the
trailer hitch. Turn off parking assist
when towing a trailer.
To turn the rear parking assist
symbols or guidance lines, see
“ Rear Camera ” under Vehicle
Personalization on page 5-42 .
Disconnecting the Rear Vision
Camera (RVC) The RVC must be disconnected if
the tailgate needs to be removed.
The RVC is disconnected by
removing the connector from the
electrical junction block mounted on
the left side of the cross member of
the vehicle frame. After
disconnecting, the cap mounted
next to the camera connector must
be relocated so that the open
terminals on the junction block are
covered.

Black plate (68,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-68 Driving and Operating Warning (Continued) keep it in contact with the fill
opening until filling is
complete. .
Fill the container no more
than 95% full to allow for
expansion. .
Do not smoke, light matches,
or use lighters while
pumping fuel. .
Avoid using cell phones or
other electronic devices. Trailer Towing General Towing
Information Only use towing equipment that has
been designed for the vehicle.
Contact your dealer or trailering
dealer for assistance with preparing
the vehicle for towing a trailer. Read
the entire section before towing a
trailer.
For towing a disabled vehicle, see
Towing the Vehicle on page 10-91 .
For towing the vehicle behind
another vehicle such as a motor
home, see Recreational Vehicle
Towing on page 10-91 .
Driving Characteristics
and Towing Tips Driving with a Trailer
When towing a trailer: .
Become familiar with the state
and local laws that apply to
trailer towing. .
Do not tow a trailer during the
first 800 km (500 mi) to prevent
damage to the engine, axle,
or other parts. .
Then during the first 800 km
(500 mi) of trailer towing, do not
drive over 80 km/h (50 mph) and
do not make starts at full throttle. .
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. .
Turn off Park Assist when
towing.
{ 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.
(Continued)

Black plate (82,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-82 Driving and Operating If the vehicle is equipped with the
heavy-duty trailering option, see
“ Heavy-Duty Trailer Wiring Harness
Package ” earlier in this section.
When the camper-wiring harness is
ordered without the heavy-duty
trailering package, a seven-wire
harness with a seven-pin connector
is 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 harness should be installed by
your dealer or a qualified service
center. 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
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. See Tow/Haul
Mode on page 9-39 .
Tow/Haul is designed to be most
effective when the vehicle and
trailer combined weight is at least
75% of the vehicle's Gross
Combined Weight Rating (GCWR).
See “ Weight of the Trailer ” under
Trailer Towing on page 9-71 . 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.

Black plate (22,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-22 Vehicle Care In addition, there are ENGINE
OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE
ENGINE, and ENGINE POWER IS
REDUCED messages in the Driver
Information Center (DIC). See
Engine Cooling System Messages
on page 5-33 and Engine Power
Messages on page 5-34 .
If the decision is made not to lift the
hood when this warning appears,
get service help right away. See
Roadside Assistance Program on
page 13-5 .
If the decision is made to lift the
hood, make sure the vehicle is
parked on a level surface.
Then check to see if the engine
cooling fan is running. If the engine
is overheating, the fan should be
running. If it is not, do not continue
to run the engine and have the
vehicle serviced. { CautionRunning the engine without
coolant may cause damage or a
fire. Vehicle damage would not be
covered by the vehicle warranty.
See Overheated Engine
Protection Operating Mode on
page 10-23 for information on
driving to a safe place in an
emergency.
If Steam is Coming from the
Engine Compartment
{ Warning
Steam from an overheated engine
can burn you badly, even if you
just open the hood. Stay away
from the engine if you see or hear
steam coming from it. Turn it off
and get everyone away from the
vehicle until it cools down. Wait
(Continued) Warning (Continued) until there is no sign of steam or
coolant before you open
the hood.
If you keep driving when the
vehicles engine is overheated,
the liquids in it can catch fire. You
or others could be badly burned.
Stop the engine if it overheats,
and get out of the vehicle until the
engine is cool.
See Overheated Engine
Protection Operating Mode on
page 10-23 for information on
driving to a safe place in an
emergency.

Black plate (75,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-75
{ WarningLifting a vehicle and getting under
it to do maintenance or repairs is
dangerous without the
appropriate safety equipment and
training. If a jack is provided with
the vehicle, it is designed only for
changing a flat tire. If it is used for
anything else, you or others could
be badly injured or killed if the
vehicle slips off the jack. If a jack
is provided with the vehicle, only
use it for changing a flat tire.
If a tire goes flat, avoid further tire
and wheel damage by driving slowly
to a level place, well off the road,
if possible. Turn on the hazard
warning flashers. See Hazard
Warning Flashers on page 6-4 .{ WarningChanging a tire can be
dangerous. The vehicle can slip
off the jack and roll over or fall
causing injury or death. Find a
level place to change the tire. To
help prevent the vehicle from
moving:
1. Set the parking brake firmly.
2. Put an automatic
transmission in P (Park) or a
manual transmission in
1 (First) or R (Reverse).
3. For four-wheel-drive
vehicles, be sure the
transfer case is in a drive
gear – not in N (Neutral).
4. Turn off the engine and do
not restart while the vehicle
is raised.
5. Do not allow passengers to
remain in the vehicle.
(Continued) Warning (Continued) 6. Place wheel blocks on both
sides of the tire at the
opposite corner of the tire
being changed.
When the vehicle has a flat tire (2),
use the following example as a
guide to assist in the placement of
the wheel blocks (1).
1. Wheel Block
2. Flat Tire
The following information explains
how to use the jack and change
a tire.

Black plate (8,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
14-8 OnStar Potential Issues OnStar cannot perform Remote
Door Unlock or Stolen Vehicle
Assistance after the vehicle has
been off continuously for five days.
After five days, OnStar can contact
Roadside Assistance and a
locksmith to help gain access to the
vehicle.
Global Positioning
System (GPS) .
Obstruction of the GPS can
occur in a large city with tall
buildings; in parking garages;
around airports; in tunnels,
underpasses; or in an area with
very dense trees. If GPS signals
are not available, the OnStar
system should still operate to
call OnStar. However, OnStar
could have difficulty identifying
the exact location. .
In emergency situations, OnStar
can use the last stored GPS
location to send to emergency
responders. A temporary loss of GPS can cause
loss of the ability to send a
Turn-by-Turn Navigation route. The
Advisor may give a verbal route or
may ask for a call back after the
vehicle is driven into an open area.
Cellular and GPS Antennas Do not place items over or near the
antenna to prevent blocking cellular
and GPS signal reception. Cellular
reception is required for OnStar to
send remote signals to the vehicle.
Unable to Connect to OnStar
Message If there is limited cellular coverage
or the cellular network has reached
maximum capacity, this message
may come on. Press
Q to try the
call again or try again after driving a
few miles into another cellular area.
Vehicle and Power Issues
OnStar services require a vehicle
electrical system, wireless service,
and GPS satellite technologies to be
available and operating for features to function properly. These systems
may not operate if the battery is
discharged or disconnected.
Add-on Electrical Equipment The OnStar system is integrated
into the electrical architecture of the
vehicle. Do not add any electrical
equipment. See Add-On Electrical
Equipment on page 9-88 . Added
electrical equipment may interfere
with the operation of the OnStar
system and cause it to not operate.
Privacy The complete OnStar Privacy
Statement may be found at
www.onstar.com (U.S.),
or www.onstar.ca (Canada). We
recommend that you review it. If you
have any questions, call
1-888-4-ONSTAR (1-888-466-7827)
or press
Q to speak with an
Advisor. Users of wireless
communications are cautioned that
the privacy of any information sent
via wireless cellular communications
cannot be assured. Third parties

Black plate (1,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
INDEX i-1
AAccessories and
Modifications . . . . . . . . . . . . . . . . . 10-3
Accessory Power . . . . . . . . . . . . . . 9-29
Active Fuel Management ®
. . . . . 9-32
Add-On Electrical
Equipment . . . . . . . . . . . . . . . . . . . 9-88
Adding a Snow Plow or
Similar Equipment . . . . . . . . . . . . 9-88
Additional Information
OnStar ®
. . . . . . . . . . . . . . . . . . . . . . 14-6
Additional Maintenance
and Care . . . . . . . . . . . . . . . . . . . . . 11-9
Adjustable Throttle and
Brake Pedal . . . . . . . . . . . . . . . . . . 9-23
Adjustments
Lumbar, Front Seats . . . . . . . . . . . 3-3
Air Cleaner/Filter, Engine . . . . . 10-15
Air Filter, Passenger
Compartment . . . . . . . . . . . . . . . . . 8-5
Air Vents . . . . . . . . . . . . . . . . . . . . . . . 8-4 Airbag System
Check . . . . . . . . . . . . . . . . . . . . . . . . 3-29
How Does an Airbag
Restrain? . . . . . . . . . . . . . . . . . . . 3-22
Passenger Sensing
System . . . . . . . . . . . . . . . . . . . . . . 3-24
What Makes an Airbag
Inflate? . . . . . . . . . . . . . . . . . . . . . . 3-22
What Will You See after an
Airbag Inflates? . . . . . . . . . . . . . 3-22
When Should an Airbag
Inflate? . . . . . . . . . . . . . . . . . . . . . . 3-20
Where Are the Airbags? . . . . . . 3-18
Airbags
Adding Equipment to the
Vehicle . . . . . . . . . . . . . . . . . . . . . . 3-28
Passenger Status Indicator . . . 5-17
Readiness Light . . . . . . . . . . . . . . 5-16
Servicing Airbag-Equipped
Vehicles . . . . . . . . . . . . . . . . . . . . . 3-28
System Check . . . . . . . . . . . . . . . . 3-17
Alarm
Vehicle Security . . . . . . . . . . . . . . 2-11
All-Season Tires . . . . . . . . . . . . . . 10-51
All-Terrain Tires . . . . . . . . . . . . . . . 10-52 Antilock Brake
System (ABS) . . . . . . . . . . . . . . . . 9-46
Warning Light . . . . . . . . . . . . . . . . . 5-21
Appearance Care
Exterior . . . . . . . . . . . . . . . . . . . . . 10-96
Interior . . . . . . . . . . . . . . . . . . . . . 10-101
Assistance Program,
Roadside . . . . . . . . . . . . . . . . . . . . . 13-5
Assistance Systems for
Driving . . . . . . . . . . . . . . . . . . . . . . . 9-59
Assistance Systems for
Parking and Backing . . . . . . . . . 9-56
Automatic
Dimming Mirrors . . . . . . . . . . . . . . 2-17
Door Locks . . . . . . . . . . . . . . . . . . . . 2-9
Headlamp System . . . . . . . . . . . . . 6-3
Transmission . . . . . . . . . . . . . . . . . 9-33
Transmission Fluid . . 10-12, 10-15
Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . . . 9-36
Shift Lock Control
Function Check . . . . . . . . . . . 10-34
Auxiliary
Roof Mounted Lamp . . . . . . . . . . . 6-5
Axle, Front . . . . . . . . . . . . . . . . . . . . 10-30
Axle, Rear . . . . . . . . . . . . . . . . . . . . 10-31

Black plate (2,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
i-2 INDEX
BBattery . . . . . . . . . . . . . . . . . . . . . . . 10-29
Jump Starting . . . . . . . . . . . . . . . 10-87
Load Management . . . . . . . . . . . . . 6-8
Power Protection . . . . . . . . . . . . . . 6-9
Voltage and Charging
Messages . . . . . . . . . . . . . . . . . . . 5-31
Blade Replacement, Wiper . . . 10-35
Blind Spot Mirrors . . . . . . . . . . . . . 2-17
Brake
Pedal and Adjustable
Throttle . . . . . . . . . . . . . . . . . . . . . . 9-23
System Warning Light . . . . . . . . 5-21
Brakes . . . . . . . . . . . . . . . . . . . . . . . . 10-26
Antilock . . . . . . . . . . . . . . . . . . . . . . . 9-46
Assist . . . . . . . . . . . . . . . . . . . . . . . . . 9-48
Fluid . . . . . . . . . . . . . . . . . . . . . . . . 10-27
Parking . . . . . . . . . . . . . . . . . . . . . . . 9-47
System Messages . . . . . . . . . . . . 5-32
Braking . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
Break-In, New Vehicle . . . . . . . . . 9-23 Bulb Replacement . . . . . . . . . . . . 10-40
Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . 10-39
Halogen Bulbs . . . . . . . . . . . . . . 10-36
Headlamp Aiming . . . . . . . . . . . 10-36
Headlamps . . . . . . . . . . . . . . . . . 10-36
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . 10-36
Taillamps, Turn Signal,
Stoplamps, and
Back-up Lamps . . . . . . . . . . . 10-37
Buying New Tires . . . . . . . . . . . . . 10-69
C Calibration . . . . . . . . . . . . . . . . . . . . . . 5-4
California
Fuel Requirements . . . . . . . . . . . 9-64
Perchlorate Materials
Requirements . . . . . . . . . . . . . . . 10-3
Warning . . . . . . . . . . . . . . . . . . . . . . 10-2
Canadian Vehicle Owners . . . . . . . . iii
Capacities and
Specifications . . . . . . . . . . . . . . . . 12-2 Carbon Monoxide
Engine Exhaust . . . . . . . . . . . . . . . 9-32
Tailgate . . . . . . . . . . . . . . . . . . . . . . . 2-10
Winter Driving . . . . . . . . . . . . . . . . 9-12
Cargo
Tie-Downs . . . . . . . . . . . . . . . . . . . . . 4-3
Cargo Lamp . . . . . . . . . . . . . . . . . . . . 6-6
Cautions, Danger, and
Warnings . . . . . . . . . . . . . . . . . . . . . . . . iv
Center Console Storage . . . . . . . . 4-2
Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 10-39
Chains, Tire . . . . . . . . . . . . . . . . . . 10-74
Charging System Light . . . . . . . . 5-18
Check
Engine Light . . . . . . . . . . . . . . . . . . 5-18
Ignition
Transmission Lock . . . . . . . . 10-34