2015 GMC SIERRA DENALI ignition

Black plate (47,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-47If driving safely on a wet road and it
becomes necessary to slam on the
brakes and continue braking to
avoid a sudden obstacle, a
computer senses the wheels are
slowing down. If one of the wheels
is about to stop rolling, the computer
will separately work the brakes at
each wheel.
ABS can change the brake pressure
to each wheel, as required, faster
than any driver could. This can help
you steer around the obstacle while
braking hard.
As the brakes are applied, the
computer keeps receiving updates
on wheel speed and controls
braking pressure accordingly.
Remember: ABS does not change
the time needed to get a foot up to
the brake pedal or always decrease
stopping distance. If you get too
close to the vehicle in front of you,
there will not be enough time to
apply the brakes if that vehicle suddenly slows or stops. Always
leave enough room up ahead to
stop, even with ABS.
Using ABS Do not pump the brakes. Just hold
the brake pedal down firmly and let
ABS work. You may hear the ABS
pump or motor operating and feel
the brake pedal pulsate. This is
normal.
Braking in Emergencies ABS allows you to steer and brake
at the same time. In many
emergencies, steering can help
more than even the very best
braking. Parking Brake
Set the parking brake by holding the
regular brake pedal down, then
pushing down the parking brake
pedal.
If the ignition is on, the brake
system warning light will come on.
See Brake System Warning Light on
page 5-21 .

Black plate (54,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-54 Driving and Operating The speedometer reading can be
displayed in either English or metric
units. See Instrument Cluster on
page 5-9 . The increment value used
depends on the units displayed.
Reducing Speed While Using
Cruise Control
If the cruise control system is
already activated: .
Press and hold the SET – button
until the desired lower speed is
reached, then release it. .
To slow down in small
increments, briefly press the
SET – button. For each press,
the vehicle goes about 1.6 km/h
(1 mph) slower.
The speedometer reading can be
displayed in either English or metric
units. See Instrument Cluster on
page 5-9 . The increment value used
depends on the units displayed. Passing Another Vehicle While
Using Cruise Control
Use the accelerator pedal to
increase the vehicle speed. When
you take your foot off the pedal, the
vehicle will slow down to the
previous set cruise speed. While
pressing the accelerator pedal or
shortly following the release to
override cruise control, briefly
pressing the SET – button will result
in cruise control set to the current
vehicle speed.
Using Cruise Control on Hills
How well the cruise control works
on hills depends on the vehicle
speed, the load, and the steepness
of the hills. When going up steep
hills, pressing the accelerator pedal
may be necessary to maintain
vehicle speed. While going downhill: .
Vehicles with a 6-speed
automatic transmission and a
gasoline engine have Cruise
Grade Braking to help maintain
driver selected speed.
Cruise Grade Braking is enabled
when the vehicle is started and
cruise control is active. It is not
enabled in Range Selection
Mode. It assists in maintaining
driver selected speed when
driving on downhill grades by
using the engine and
transmission to slow the vehicle.
To disable and enable Cruise
Grade Braking for the current
ignition key cycle, press and
hold the Tow/Haul button for
five seconds. A DIC message
displays. See Transmission
Messages on page 5-39 . .
Vehicles with a diesel engine
have Cruise Grade Braking
enabled when Tow/Haul Mode is
on, the exhaust brake is on,
or both are on.

Black plate (55,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-55For other forms of Grade Braking,
see Automatic Transmission on
page 9-33 , Tow/Haul Mode on
page 9-39 , and Hill Descent Control
(HDC) on page 9-51 .
Ending Cruise Control
There are four ways to end cruise
control: .
Step lightly on the brake pedal. .
Press
* ..
Shift the transmission to
N (Neutral). .
To turn off cruise control,
press
5 .
Erasing Speed Memory
The cruise control set speed is
erased from memory if
5 is pressed
or the ignition is turned off. Driver Assistance
Systems This vehicle may have features that
work together to help avoid crashes
or reduce crash damage while
driving, backing, and parking. Read
this entire section before using
these systems.
{ WarningDo not rely on the Driver
Assistance Systems. These
systems do not replace the need
for paying attention and driving
safely. You may not hear or feel
alerts or warnings provided by
these systems. Failure to use
proper care when driving may
result in injury, death, or vehicle
damage. See Defensive Driving
on page 9-3 .
(Continued) Warning (Continued) Under many conditions, these
systems will not: .
Detect children, pedestrians,
bicyclists, or animals. .
Detect vehicles or objects
outside the area monitored by
the system. .
Work at all driving speeds. .
Warn you or provide you with
enough time to avoid a crash. .
Work under poor visibility or
bad weather conditions. .
Work if the detection sensor
is not cleaned or is covered
by ice, snow, mud, or dirt.
Complete attention is always
required while driving, and you
should be ready to take action
and apply the brakes and/or steer
the vehicle to avoid crashes.

Black plate (83,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-83Operating 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.
Integrated Trailer Brake
Control System The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for use with electric trailer brakes or
most electric over hydraulic trailer
brakes. This symbol is on the Trailer Brake
Control Panel on vehicles with an
ITBC system. The power output to
the trailer brakes is based on the
amount of brake pressure being
applied by the vehicle ’ s brake
system, and on the type of trailer
brakes detected. This available
power output to the trailer brakes
can be adjusted to a wide range of
trailering situations.
The ITBC system is integrated with
the vehicle ’ s brake, antilock brake,
and StabiliTrak systems. In trailering
conditions that cause the vehicle ’ s
antilock brake or StabiliTrak
systems to activate, power sent to
the trailer's brakes will be
automatically adjusted to minimize
trailer wheel lock-up. This does not
imply that the trailer has StabiliTrak.
If the vehicle ’ s brake, antilock brake,
or StabiliTrak systems are not
functioning properly, the ITBC
system may not be fully functional
or may not function at all. Make sure all of these systems are fully
operational to ensure full
functionality of the ITBC system.
The ITBC system is powered
through the vehicle's electrical
system. Turning the ignition off will
also turn off the ITBC system. The
ITBC system is fully functional only
when the ignition is in ON/RUN.
{ WarningConnecting a trailer that has an
air brake system may result in
reduced or complete loss of trailer
braking. There may be an
increase in stopping distance or
trailer instability which could
result in personal injury or
damage to the vehicle, trailer,
or other property. Use the ITBC
system only with electric or
electric over hydraulic trailer
brakes.

Black plate (86,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-86 Driving and Operating 3. Readjust Trailer Gain anytime
vehicle loading, trailer loading,
or road surface conditions
change or if trailer wheel lock-up
is noticed at any time while
towing.
Other ITBC-Related DIC Messages
In addition to displaying TRAILER
GAIN and OUTPUT through the
DIC, trailer connection and ITBC
system status are displayed on
the DIC.
TRAILER CONNECTED: This
message will briefly display when a
trailer with electric brakes is first
connected to the vehicle. This
message will automatically turn off
in about 10 seconds. This message
can be acknowledged before it
automatically turns off. CHECK TRAILER WIRING: This
message will display if: .
The ITBC system first
determines connection to a
trailer with electric brakes and
then the trailer harness becomes
disconnected from the vehicle.
If the disconnect occurs while
the vehicle is stationary, this
message will automatically turn
off in about 30 seconds. This
message will also turn off if it is
acknowledged or if the trailer
harness is reconnected.
If the disconnect occurs while
the vehicle is moving, this
message will continue until the
ignition is turned off. This
message will also turn off if it is
acknowledged or if the trailer
harness is reconnected. .
There is an electrical fault in the
wiring to the trailer brakes. This
message will continue as long
as there is an electrical fault in the trailer wiring. This message
will also turn off if it is
acknowledged.
To determine if the electrical fault is
on the vehicle side or trailer side of
the trailer wiring harness
connection:
1. Disconnect the trailer wiring
harness from the vehicle.
2. Turn the ignition off.
3. Wait 10 seconds, then turn the
ignition back to RUN.
4. If the CHECK TRAILER WIRING
message reappears, the
electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING
message only reappears when
connecting the trailer wiring
harness to the vehicle, the
electrical fault is on the
trailer side.
SERVICE TRAILER BRAKE
SYSTEM: This message will display
when there is a problem with the
ITBC system. If this message

Black plate (87,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-87continues over multiple ignition
cycles, there is a problem with the
ITBC system. Have the vehicle
serviced.
If either the CHECK TRAILER
WIRING or SERVICE TRAILER
BRAKE SYSTEM message displays
while driving, the ITBC system may
not be fully functional or may not
function at all. When traffic
conditions allow, carefully pull the
vehicle over to the side of the road
and turn the ignition off. Check the
wiring connection to the trailer and
turn the ignition back on. If either of
these messages continues, either
the vehicle or trailer needs service.
A GM dealer may be able to
diagnose and repair problems with
the trailer. However, any diagnosis
and repair of the trailer is not
covered under the vehicle warranty.
Contact your trailer dealer for
assistance with trailer repairs and
trailer warranty information. Trailer Sway
Control (TSC) Vehicles with StabiliTrak have a
TSC feature. Trailer sway is
unintended side-to-side motion of a
trailer while being towed. If the
vehicle is towing a trailer and the
TSC detects that sway is increasing,
the vehicle brakes are selectively
applied at each wheel, to help
reduce excessive trailer sway. If the
vehicle is equipped with the
Integrated Trailer Brake Control
(ITBC) system, and the trailer has
the electric actuated brake system,
StabiliTrak may also apply the trailer
brakes.
If TSC is enabled, the Traction
Control System (TCS)/StabiliTrak
warning light will flash on the
instrument cluster. Vehicle speed
must be reduced. If trailer sway
continues, StabiliTrak can reduce
engine torque to help slow the
vehicle. See Traction Control/
Electronic Stability Control on
page 9-49 .{ WarningEven if the vehicle is equipped
with TSC, trailer sway could result
in loss of control and the vehicle
could crash. If excessive trailer
sway is detected, slow down to a
safe speed. Check the trailer and
vehicle to help correct possible
causes. These could include an
improperly or overloaded trailer,
unrestrained cargo, improper
trailer hitch configuration,
excessive vehicle-trailer speed,
or improperly inflated or incorrect
vehicle or trailer tires. See Towing
Equipment on page 9-78 for
trailer ratings and hitch setup
recommendations.
Adding non-dealer accessories can
affect the vehicle performance. See
Accessories and Modifications on
page 10-3 .

Black plate (1,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-1
Vehicle Care General Information General Information . . . . . . . . . . 10-2
California Proposition
65 Warning . . . . . . . . . . . . . . . . . 10-2
California Perchlorate
Materials Requirements . . . . 10-3
Accessories and
Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks Doing Your Own
Service Work . . . . . . . . . . . . . . . 10-3
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-4
Engine Compartment
Overview . . . . . . . . . . . . . . . . . . . 10-5
Engine Oil . . . . . . . . . . . . . . . . . . . 10-8
Engine Oil Life System . . . . . 10-11
Automatic Transmission
Fluid (6 Speed
Transmission) . . . . . . . . . . . . . 10-12
Automatic Transmission
Fluid (8 Speed
Transmission) . . . . . . . . . . . . . 10-15
Engine Air Cleaner/Filter . . . . 10-15
Cooling System . . . . . . . . . . . . 10-17
Engine Coolant . . . . . . . . . . . . . 10-18 Engine Overheating . . . . . . . . 10-21
Overheated Engine
Protection
Operating Mode . . . . . . . . . . . 10-23
Engine Fan . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid (1500
Series) . . . . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid (2500/
3500 Series) . . . . . . . . . . . . . . 10-24
Washer Fluid . . . . . . . . . . . . . . . 10-25
Brakes . . . . . . . . . . . . . . . . . . . . . 10-26
Brake Fluid . . . . . . . . . . . . . . . . . 10-27
Battery . . . . . . . . . . . . . . . . . . . . . 10-29
Four-Wheel Drive . . . . . . . . . . . 10-29
Front Axle . . . . . . . . . . . . . . . . . . 10-30
Rear Axle . . . . . . . . . . . . . . . . . . 10-31
Noise Control System . . . . . . 10-32
Starter Switch Check . . . . . . . 10-33
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-34
Ignition Transmission Lock
Check . . . . . . . . . . . . . . . . . . . . . 10-34
Park Brake and P (Park)
Mechanism Check . . . . . . . . 10-34
Wiper Blade
Replacement . . . . . . . . . . . . . . 10-35
Glass Replacement . . . . . . . . 10-35 Headlamp Aiming Headlamp Aiming . . . . . . . . . . 10-36
Bulb Replacement Bulb Replacement . . . . . . . . . . 10-36
Halogen Bulbs . . . . . . . . . . . . . . 10-36
LED Lighting . . . . . . . . . . . . . . . 10-36
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . 10-36
Fog Lamps . . . . . . . . . . . . . . . . . 10-37
Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-37
Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . 10-39
Replacement Bulbs . . . . . . . . . 10-40
Electrical System Electrical System
Overload . . . . . . . . . . . . . . . . . . 10-40
Fuses . . . . . . . . . . . . . . . . . . . . . . 10-41
Engine Compartment Fuse
Block . . . . . . . . . . . . . . . . . . . . . 10-41
Instrument Panel Fuse
Block (Left) . . . . . . . . . . . . . . . 10-45
Instrument Panel Fuse Block
(Right) . . . . . . . . . . . . . . . . . . . . 10-48

Black plate (12,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-12 Vehicle Care The oil life system can also be reset
as follows:
1. Turn the ignition to ON/RUN with
the engine off.
2. Fully press the accelerator pedal
slowly three times within
five seconds.
3. Display the OIL LIFE
REMAINING on the DIC. If the
display shows 100%, the system
is reset.
If the vehicle has a CHANGE
ENGINE OIL SOON message and it
comes back on when the vehicle is
started and/or the OIL LIFE
REMAINING is near 0%, the engine
oil life system has not been reset.
Repeat the procedure. Automatic Transmission
Fluid (6 Speed
Transmission) When to Check and Change
Automatic Transmission Fluid It is usually not necessary to check
the transmission fluid level. The only
reason for fluid loss is a
transmission leak or overheated
transmission. If a small leak is
suspected, then use the following
checking procedures to check the
fluid level. However, if there is a
large leak, then it may be necessary
to have the vehicle towed to a
dealer service department and have
it repaired before driving the vehicle
further.
{ Caution
Use of the incorrect automatic
transmission fluid may damage
the vehicle, and the damage may
(Continued) Caution (Continued) not be covered by the vehicle
warranty. Always use the
automatic transmission fluid listed
in Recommended Fluids and
Lubricants on page 11-12 .
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule on
page 11-3 . Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants on page 11-12 .
How to Check Automatic
Transmission Fluid
{ Caution
Too much or too little fluid can
damage the transmission. Too
much can mean that some of the
fluid could come out and fall on
hot engine parts or exhaust
(Continued)