2015 GMC SIERRA parking brake

Black plate (46,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-46 Driving and Operating
This will take at least
10 seconds. Then slowly release
the dial to the 4
nposition. The
N (Neutral) light will come on
when the transfer case shift to
N (Neutral) is complete.
7. With the engine running, verify that the transfer case is in
N (Neutral) by shifting the
transmission to R (Reverse),
then shift the transmission to
D (Drive). There should be no
movement of the vehicle while
shifting the transmission.
8. Turn the engine off, and the ignition 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:
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 the desired setting.
After the transfer case has
shifted out of N (Neutral), the
N (Neutral) light will go out.
5. Release the parking brake.
6. Start the engine and shift the transmission to the desired gear.
Brakes
Antilock Brake
System (ABS)
This vehicle has ABS, an advanced
electronic braking system that helps
prevent a braking skid.
When the vehicle begins to drive
away, ABS checks itself.
A momentary motor or clicking noise
might be heard while this test is
going on, and it might even be
noticed that the brake pedal moves
a little. This is normal.
If there is a problem with ABS, this
warning light stays on. See Antilock
Brake System (ABS) Warning Light
on page 5-21.

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 9-47
If 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 vehiclesuddenly 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 (48,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-48 Driving and Operating
{Caution
Driving with the parking brake on
can overheat the brake system
and cause premature wear or
damage to brake system parts.
Make sure that the parking brake
is fully released and the brake
warning light is off before driving.
To release the parking brake, hold
the regular brake pedal down, then
push down momentarily on the
parking brake pedal until you feel
the pedal release. Slowly pull your
foot up off the parking brake pedal.
If the parking brake is not released
when you begin to drive, the brake
system warning light will flash and a
chime will sound warning you that
the parking brake is still on.
If you are towing a trailer and are
parking on a hill, see Driving
Characteristics and Towing Tips on
page 9-68.
Brake Assist
The Brake Assist feature is
designed to assist the driver in
stopping or decreasing vehicle
speed in emergency driving
conditions. This feature uses the
stability system hydraulic brake
control module to supplement the
power brake system under
conditions where the driver has
quickly and forcefully applied the
brake pedal in an attempt to quickly
stop or slow down the vehicle. The
stability system hydraulic brake
control module increases brake
pressure at each corner of the
vehicle until the ABS activates.
Minor brake pedal pulsation or
pedal movement during this time is
normal and the driver should
continue to apply the brake pedal as
the driving situation dictates. The
Brake Assist feature will
automatically disengage when the
brake pedal is released or brake
pedal pressure is quickly
decreased.
Hill Start Assist (HSA)
This vehicle has an HSA feature,
which may be useful when the
vehicle is stopped on a grade. This
feature is designed to prevent the
vehicle from rolling, either forward or
rearward, during vehicle drive off.
After you completely stop and hold
the vehicle in a complete standstill
on a grade, HSA will automatically
activate. During the transition period
between when you release the
brake pedal and start to accelerate
to drive off on a grade, HSA holds
the braking pressure for a maximum
of two seconds to ensure that there
is no rolling. The brakes will
automatically release when the
accelerator pedal is applied within
the two-second window. If the
vehicle is equipped with the
Integrated Trailer Brake Control
(ITBC) system, HSA may also apply
the trailer brakes. It will not activate
if the vehicle is in a drive gear and
facing downhill or if the vehicle is
facing uphill and in R (Reverse).
There may be situations on minor

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 9-55
For other forms of Grade Braking,
seeAutomatic 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
5is 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.
{Warning
Do 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 (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 (81,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-81
Basic Trailer Wiring
All regular, double cab, and crew
cab pickups have a seven-wire
trailer towing harness.
For vehicles not equipped with
heavy-duty trailering, the harness is
secured to the vehicle's frame
behind the spare tire mount. The
harness requires the installation of a
trailer connector, which is available
through your dealer.
Heavy-Duty Trailer Wiring Harness
PackageFor vehicles equipped with
heavy-duty trailering, the harness
connector is mounted in the bumper.
The seven-wire harness contains
the following trailer circuits:
.Green/Violet: Left Stop/Turn
Signal
.Yellow/Gray: Right Stop/Turn
Signal
.Gray/Brown: Taillamps/Parking
Lamps
.White: Ground
.White/Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake
If charging a remote (non-vehicle)
battery, press the Tow/Haul Mode
button, if equipped, at the end of the
shift lever. This will boost the
vehicle system voltage and properly
charge the battery. If the trailer is
too light for Tow/Haul Mode, or the
vehicle is not equipped with Tow/ Haul, turn on the headlamps as a
second way to boost the vehicle
system and charge the battery.
Camper/Fifth-Wheel Trailer Wiring
Package
The seven-wire camper harness is
under the rear bumper, attached to
the frame near the rear
crossmember. A connector must be
added to the wiring harness that
connects to the camper.
The harness contains the following
camper/trailer circuits:
.Green/Violet: Left Stop/Turn
Signal
.Yellow/Gray: Right Stop/Turn
Signal
.Gray/Brown: Taillamps/Parking
Lamps
.White: Ground
.White/Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake

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 (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 Proposition65 Warning . . . . . . . . . . . . . . . . . 10-2
California Perchlorate Materials Requirements . . . . 10-3
Accessories and Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks
Doing Your OwnService 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