
Black plate (51,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-51
press and release thegbutton. The
traction off light
idisplayed in the
instrument cluster will turn off.
If TCS is limiting wheel spin when
the
gbutton is pressed, the system
will not turn off until the wheels stop
spinning.
To turn off both TCS and StabiliTrak,
press and hold the
gbutton until
the traction off light
iand the
StabiliTrak OFF light
gcome on
and stay on in the instrument
cluster, then release. The
appropriate message will display in
the DIC. See Ride Control System
Messages on page 5-36.
To turn TCS and StabiliTrak on
again, press and release the
g
button. The traction off lightiand
the StabiliTrak OFF light
gin the
instrument cluster turn off. StabiliTrak will automatically turn on
if the vehicle exceeds 56 km/h
(35 mph). Traction control will
remain off.
The vehicle has a Trailer Sway
Control (TSC) feature and a Hill
Start Assist (HSA) feature. See
Trailer Sway Control (TSC) on
page 9-87
orHill Start Assist (HSA)
on page 9-48.
Adding accessories can affect the
vehicle performance. See
Accessories and Modifications on
page 10-3.
Hill Descent
Control (HDC)
If equipped, HDC can be used when
driving downhill. It sets and
maintains vehicle speed while
descending a very steep incline in a
forward or reverse gear.
The HDC switch is on the center
stack, below the climate controls. Press
5to enable or disable HDC.
Vehicle speed must be below
50 km/h (31 mph).
The HDC light displays on the
instrument cluster when enabled.
HDC can maintain vehicle speeds
between 3 and 22 km/h (2 and
14 mph) on an incline greater than
or equal to a 10% grade. A blinking
HDC light indicates the system is
actively applying the brakes to
maintain vehicle speed.
When HDC is activated, the initial
HDC speed is set to the current
driving speed. It can be increased or
decreased by applying the
accelerator or brake pedal. This
adjusted speed becomes the new
set speed.

Black plate (52,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-52 Driving and Operating
HDC will remain enabled between
22 and 60 km/h (14 and 37 mph);
however vehicle speed cannot be
set or maintained in this range.
It will automatically disable if the
vehicle speed is above 80 km/h
(50 mph) or above 60 km/h
(37 mph) for at least
30 seconds.
5must be pressed
again to re-enable HDC.
When enabled, if the vehicle is at a
speed above 22 km/h (14 mph) and
less than 60 km/h (37 mph), a DIC
message will display. See Vehicle
Speed Messages on page 5-42.
Locking Rear Axle
Vehicles with a locking rear axle can
give more traction on snow, mud,
ice, sand, or gravel. It works like a
standard axle most of the time, but
when traction is low, this feature will
allow the rear wheel with the most
traction to move the vehicle.
Cruise Control
With cruise control a speed of about
40 km/h (25 mph) or more can be
maintained without keeping your
foot on the accelerator. Cruise
control does not work at speeds
below about 40 km/h (25 mph).
{Warning
Cruise control can be dangerous
where you cannot drive safely at
a steady speed. Do not use
cruise control on winding roads or
in heavy traffic.
Cruise control can be dangerous
on slippery roads. On such roads,
fast changes in tire traction can
cause excessive wheel slip, and
you could lose control. Do not use
cruise control on slippery roads. If equipped with an Allison or
Hydra-Matic 6-speed automatic
transmission, see
“Tow/Haul Mode
Grade Braking” underTow/Haul
Mode on page 9-39 for an
explanation of how cruise control
interacts with the Range Selection
Mode, Tow/Haul Mode, and Grade
Braking systems.
If the cruise control is being used
and the Traction Control System
(TCS) or StabiliTrak begins to limit
wheel spin, the cruise control will
automatically disengage. See
Traction Control/Electronic Stability
Control on page 9-49. If a collision
alert occurs when cruise control is
activated, cruise control is
disengaged. See Forward Collision
Alert (FCA) System on page 9-59.
When road conditions allow you to
safely use it again, cruise control
can be turned back on.
If the brakes are applied, the cruise
control disengages.

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 (61,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-61
Selecting the Alert Timing
The FCA control is on the steering
wheel. Press
[to set the FCA
timing to Far, Medium, Near, or Off.
The first button press shows the
current setting on the DIC.
Additional button presses will
change this setting. The chosen
setting will remain until it is changed
and will affect the timing of both the
Collision Alert and the Tailgating
Alert features. The timing of both
alerts will vary based on vehicle
speed. The faster the vehicle speed,
the farther away the alert will occur. Consider traffic and weather
conditions when selecting the alert
timing. The range of selectable alert
timing may not be appropriate for all
drivers and driving conditions.
Unnecessary Alerts
FCA may provide unnecessary
alerts for turning vehicles, vehicles
in other lanes, objects that are not
vehicles, or shadows. These alerts
are normal operation and the
vehicle does not need service.
Cleaning the System
If the FCA system does not seem to
operate properly, cleaning the
outside of the windshield in front of
the rearview mirror, and cleaning the
front of the vehicle where radar
sensors are located, may correct
the issue.
Lane Departure
Warning (LDW)
If equipped, LDW may help avoid
crashes due to unintentional lane
departures. It may provide an alert if
the vehicle is crossing a lane
marking without using a turn signal
in that direction. LDW uses a
camera sensor to detect the lane
markings at speeds of 56 km/h
(35 mph) or greater.
{Warning
The LDW system does not steer
the vehicle. The LDW system
may not:
.Provide enough time to avoid
a crash.
.Detect lane markings under
poor weather or visibility
conditions. This can occur if
the windshield or headlamps
are blocked by dirt, snow,
or ice; if they are not in
(Continued)

Black plate (69,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-69
Warning (Continued)
When towing a trailer:
.Do not drive with the liftgate,
trunk/hatch, or rear-most
window open.
.Fully open the air outlets on
or under the instrument
panel.
.Also adjust the climate
control system to a setting
that brings in only outside air.
See“Climate Control
Systems” in the Index.
For more information about
Carbon Monoxide, see Engine
Exhaust on page 9-32.
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.
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
{Caution
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.

Black plate (70,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-70 Driving and Operating
If the trailer turn signal bulbs burn
out, the arrows on the instrument
cluster 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
gearbefore starting 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 9-39.
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. To avoid this,
let the engine run while parked,
preferably on level ground, with the
transmission in P (Park) for a few
minutes before turning the engine
off. If the overheat warning comes
on, see
Engine Overheating on
page 10-21.
Parking on Hills
{Warning
Parking the vehicle on a hill with
the trailer attached can be
dangerous. If something goes
wrong, the rig could start to move.
People can be injured, and both
the vehicle and the trailer can be
damaged. When possible, always
park the rig on a flat surface. If parking the rig on a hill:
1. Press the brake pedal, but do
not shift into P (Park) yet. Turn
the wheels into the curb if facing
downhill or into traffic if facing
uphill.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the regular brakes
until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift
into P (Park).
5. Release the brake pedal.
Leaving After Parking on a Hill
1. Apply and hold the brake pedal.
2. Start the engine.
3. Shift into a gear.
4. Release the parking brake.
5. Let up on the brake pedal.
6. Drive slowly until the trailer is clear of the chocks.

Black plate (72,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-72 Driving and Operating
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy.
Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how the rig is used.
Speed, altitude, road grades,
outside temperature, and how much
the vehicle is used to pull a trailer
are all important. It can depend on
any special equipment on the
vehicle, and the amount of tongueweight the vehicle can carry. See
“Weight of the Trailer Tongue”
later
in this section for more information.
Trailer weight rating (TWR) for 1500
series trucks is calculated assuming
the tow vehicle has the driver, a
front seat passenger, and all
required trailering equipment.
Weight of additional optional
equipment, passengers, and cargo
in the tow vehicle must be
subtracted from the trailer weight
rating.
Trailer weight rating (TWR) for
2500 and 3500 series trucks is
calculated assuming the tow vehicle
has only the driver but all required
trailering equipment. Weight of
additional optional equipment,
passengers, and cargo in the tow
vehicle must be subtracted from the
trailer weight rating. Ask your dealer for trailering
information or advice.
For kingpin weight and trailer
tongue weight information, see
“Weight of the Trailer Tongue”
later
in this section.
Use the following chart to determine
how much the vehicle can weigh,
based upon the vehicle model and
options.
Weights listed apply for
conventional trailers and fifth-wheel
trailers unless otherwise noted.

Black plate (73,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-73
VehicleAxle Ratio Maximum Trailer Weight GCWR (a)
1500 Series 2WD Crew Cab Standard Box 5.3L V8 3.234 219 kg (9,300 lb) 6 804 kg (15,000 lb)
6.2L V8 3.234 128 kg (9,100 lb) 6 804 kg (15,000 lb)
1500 Series 2WD Crew Cab Short Box (b) 5.3L V8 3.424 264 kg (9,400 lb) 6 804 kg (15,000 lb)
6.2L V8 3.234 173 kg (9,200 lb) 6 804 kg (15,000 lb)
1500 Series 4WD Crew Cab Standard Box 5.3L V8 3.424 128 kg (9,100 lb) 6 804 kg (15,000 lb)
6.2L V8 3.233 992 kg (8,800 lb) 6 804 kg (15,000 lb)
1500 Series 4WD Crew Cab Short Box (b) 5.3L V8 3.424 173 kg (9,200 lb) 6 804 kg (15,000 lb)
6.2L V8 3.234 037 kg (8,900 lb) 6 804 kg (15,000 lb)
2500 Series 2WD Crew Cab Standard Box
6.0L V8 3.734 445 kg (9,800 lb) 7 257 kg (16,000 lb)
6.0L V8 –Conventional Trailer 4.105 897 kg (13,000 lb) 9 299 kg (20,500 lb)
6.0L V8 –Fifth-Wheel Trailer 4.106 486 kg (14,300 lb) 9 299 kg (20,500 lb)