2015 GMC SIERRA DENALI service

Black plate (27,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-27proper sequence to torque
specifications in Capacities and
Specifications on page 12-2 .
Brake linings should always be
replaced as complete axle sets.
Brake Pedal Travel See your dealer if the brake pedal
does not return to normal height,
or if there is a rapid increase in
pedal travel. This could be a sign
that brake service might be
required.
Brake Adjustment Every time the brakes are applied,
with or without the vehicle moving,
the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is
complex. Its many parts have to be
of top quality and work well together
if the vehicle is to have really good
braking. The vehicle was designed
and tested with top-quality brake
parts. When parts of the braking
system are replaced, be sure to get new, approved replacement parts.
If this is not done, the brakes might
not work properly. For example,
installing disc brake pads that are
wrong for the vehicle, can change
the balance between the front and
rear brakes — for the worse. The
braking performance expected can
change in many other ways if the
wrong replacement brake parts are
installed.
Brake Fluid
The brake master cylinder reservoir
is filled with DOT 3 brake fluid. See
Engine Compartment Overview on
page 10-5 for the location of the
reservoir. There are only two reasons why the
brake fluid level in the reservoir
might go down: .
The brake fluid level goes down
because of normal brake lining
wear. When new linings are
installed, the fluid level goes
back up. .
A fluid leak in the brake
hydraulic system can also cause
a low fluid level. Have the brake
hydraulic system fixed, since a
leak means that sooner or later
the brakes will not work well.
Do not top off the brake fluid.
Adding fluid does not correct a leak.
If fluid is added when the linings are
worn, there will be too much fluid
when new brake linings are
installed. Add or remove brake fluid,
as necessary, only when work is
done on the brake hydraulic system.

Black plate (33,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-33purpose of noise control, prior to
its sale or delivery to the ultimate
purchaser or while it is in use; or
2. The use of the vehicle after such
device or element of design has
been removed or rendered
inoperative by any person.
Among those acts presumed to
constitute tampering are the acts
listed below.
Insulation:
Removal of the noise shields or any
underhood insulation.
Engine:
Removal or rendering engine speed
governor, if the vehicle has one,
inoperative so as to allow engine
speed to exceed manufacturer
specifications. Fan and Drive: .
Removal of fan clutch, if the
vehicle has one, or rendering
clutch inoperative. .
Removal of the fan shroud, if the
vehicle has one.
Air Intake: .
Removal of the air cleaner
silencer. .
Modification of the air cleaner.
Exhaust: .
Removal of the muffler and/or
resonator. .
Removal of the exhaust pipes
and exhaust pipe clamps. Starter Switch Check
{ WarningWhen you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be
sure there is enough room
around the vehicle.
2. Apply both the parking brake
and the regular brake.
Do not use the accelerator
pedal, and be ready to turn off
the engine immediately if it
starts.
3. Try to start the engine in each
gear. The vehicle should start
only in P (Park) or N (Neutral).
If the vehicle starts in any other
position, contact your dealer for
service.

Black plate (34,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-34 Vehicle Care
Automatic Transmission
Shift Lock Control
Function Check
{ WarningWhen you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be
sure there is enough room
around the vehicle. It should be
parked on a level surface.
2. Apply the parking brake. Be
ready to apply the regular brake
immediately if the vehicle begins
to move.
3. With the engine off, turn the
ignition on, but do not start the
engine. Without applying the
regular brake, try to move the
shift lever out of P (Park) with normal effort. If the shift lever
moves out of P (Park), contact
your dealer for service.
Ignition Transmission
Lock Check While parked and with the parking
brake set, try to turn the ignition to
LOCK/OFF in each shift lever
position. .
The ignition should turn to
LOCK/OFF only when the shift
lever is in P (Park). .
The ignition key should come
out only in LOCK/OFF.
Contact your dealer if service is
required. Park Brake and P (Park)
Mechanism Check
{ WarningWhen you are doing this check,
the vehicle could begin to move.
You or others could be injured
and property could be damaged.
Make sure there is room in front
of the vehicle in case it begins to
roll. Be ready to apply the regular
brake at once should the vehicle
begin to move.
Park on a fairly steep hill, with the
vehicle facing downhill. Keeping
your foot on the regular brake, set
the parking brake. .
To check the parking brake's
holding ability: With the engine
running and the transmission in
N (Neutral), slowly remove foot
pressure from the regular brake
pedal. Do this until the vehicle is
held by the parking brake only.

Black plate (35,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-35.
To check the P (Park)
mechanism's holding ability:
With the engine running, shift to
P (Park). Then release the
parking brake followed by the
regular brake.
Contact your dealer if service is
required.
Wiper Blade Replacement Windshield wiper blades should be
inspected for wear or cracking.
Replacement blades come in
different types and are removed in
different ways. For proper
windshield wiper blade length and
type, see Maintenance
Replacement Parts on page 11-14 .
{ Caution
Allowing the wiper arm to touch
the windshield when no wiper
blade is installed could damage
the windshield. Any damage that
(Continued) Caution (Continued) occurs would not be covered by
your warranty. Do not allow the
wiper arm to touch the windshield.
To replace the windshield wiper
blade:
1. Pull the windshield wiper
assembly away from the
windshield. 2. Press the button (2) in the
middle of the wiper arm
connector, and pull the wiper
blade away from the arm
connector (1).
3. Remove the wiper blade.
4. Reverse Steps 1 – 3 for wiper
blade replacement.
Glass Replacement If the windshield or front side glass
must be replaced, see your dealer
to determine the correct
replacement glass.

Black plate (50,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-50 Vehicle Care
Wheels and Tires Tires Every new GM vehicle has
high-quality tires made by a
leading tire manufacturer. See
the warranty manual for
information regarding the tire
warranty and where to get
service. For additional
information refer to the tire
manufacturer.
{ Warning.
Poorly maintained and
improperly used tires are
dangerous. .
Overloading the tires can
cause overheating as a
result of too much flexing.
There could be a blowout
(Continued) Warning (Continued)
and a serious crash. See
Vehicle Load Limits on
page 9-15 . .
Underinflated tires pose
the same danger as
overloaded tires. The
resulting crash could
cause serious injury.
Check all tires frequently
to maintain the
recommended pressure.
Tire pressure should be
checked when the tires
are cold. .
Overinflated tires are more
likely to be cut, punctured,
or broken by a sudden
impact — such as when
hitting a pothole. Keep
tires at the recommended
pressure.
(Continued) Warning (Continued) .
Worn or old tires can
cause a crash. If the tread
is badly worn,
replace them. .
Replace any tires that
have been damaged by
impacts with potholes,
curbs, etc. .
Improperly repaired tires
can cause a crash. Only
the dealer or an
authorized tire service
center should repair,
replace, dismount, and
mount the tires. .
Do not spin the tires in
excess of 56 km/h
(35 mph) on slippery
surfaces such as snow,
mud, ice, etc. Excessive
spinning may cause the
tires to explode.

Black plate (52,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-52 Vehicle Care Caution (Continued)occur when coming into contact
with road hazards like potholes,
or sharp edged objects, or when
sliding into a curb. The warranty
does not cover this type of
damage. Keep tires set to the
correct inflation pressure and
when possible, avoid contact with
curbs, potholes, and other road
hazards.
All-Terrain Tires This vehicle may have all-terrain
tires. These tires provide good
performance on most road surfaces,
weather conditions, and for off-road
driving. See Off-Road Driving on
page 9-6 .
The tread pattern on these tires may
wear more quickly than other tires.
Consider rotating the tires more
frequently than at 12 000 km
(7,500 mi) intervals if irregular wear is noted when the tires are
inspected. See Tire Inspection on
page 10-65 .
Tire Sidewall Labeling Useful information about a tire is
molded into the sidewall. The
examples show a typical
passenger and light truck tire
sidewall.
Passenger (P-Metric)/Spare Tire
(1) Tire Size :
The tire size code
is a combination of letters and
numbers used to define a particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“ Tire Size ” illustration later in this
section for more detail.
(2) TPC Spec (Tire
Performance Criteria
Specification) :
Original
equipment tires designed to
GM's specific tire performance
criteria have a TPC specification
code molded onto the sidewall.
GM's TPC specifications meet or
exceed all federal safety
guidelines.
(3) DOT (Department of
Transportation) :
The
Department of Transportation
(DOT) code indicates that the
tire is in compliance with the
U.S. Department of
Transportation Motor Vehicle
Safety Standards.

Black plate (53,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-53DOT Tire Date of
Manufacture :
The last four
digits of the TIN indicate the tire
manufactured date. The first two
digits represent the week
(01-52) and the last two digits,
the year. For example, the third
week of the year 2010 would
have a four-digit DOT date
of 0310.
(4) Tire Identification Number
(TIN) :
The letters and numbers
following the DOT code are the
Tire Identification Number (TIN).
The TIN shows the
manufacturer and plant code,
tire size, and date the tire was
manufactured. The TIN is
molded onto both sides of the
tire, although only one side may
have the date of manufacture.
(5) Tire Ply Material :
The type
of cord and number of plies in
the sidewall and under the tread. (6) Uniform Tire Quality
Grading (UTQG) :
Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more
information, see Uniform Tire
Quality Grading on page 10-71 .
(7) Maximum Cold Inflation
Load Limit :
Maximum load that
can be carried and the
maximum pressure needed to
support that load. For
information on recommended
tire pressure see Tire Pressure
on page 10-59 and Vehicle Load
Limits on page 9-15 .
(8) Temporary Use Only :
Only
use a temporary spare tire until
the road tire is repaired and
replaced. This spare tire should
not be driven on over 112 km/h
(70 mph), or 88 km/h (55 mph)
when pulling a trailer, with the proper inflation pressure. See
Full-Size Spare Tire on
page 10-86 .
Light Truck (LT-Metric) Tire
(1) Tire Size :
The tire size code
is a combination of letters and
numbers used to define a
particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“ Tire Size ” illustration later in this
section for more detail.

Black plate (55,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-55
Passenger (P-Metric) Tire
(1) Passenger (P-Metric) Tire :
The United States version of a
metric tire sizing system. The
letter P as the first character in
the tire size means a passenger
vehicle tire engineered to
standards set by the U.S. Tire
and Rim Association.
(2) Tire Width :
The three-digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(3) Aspect Ratio :
A two-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size
aspect ratio is 75, as shown in
item C of the tire illustration, it would mean that the tire's
sidewall is 75 percent as high as
it is wide.
(4) Construction Code :
A letter
code is used to indicate the type
of ply construction in the tire.
The letter R means radial ply
construction; the letter D means
diagonal or bias ply
construction; and the letter B
means belted-bias ply
construction.
(5) Rim Diameter :
Diameter of
the wheel in inches.
(6) Service Description :
These
characters represent the load
index and speed rating of the
tire. The load index represents
the load carrying capacity a tire
is certified to carry. The speed
rating is the maximum speed a
tire is certified to carry a load. Light Truck (LT-Metric) Tire
(1) Light Truck (LT-Metric)
Tire :
The United States version
of a metric tire sizing system.
The letters LT as the first two
characters in the tire size mean
a light truck tire engineered to
standards set by the U.S. Tire
and Rim Association.
(2) Tire Width :
The three-digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(3) Aspect Ratio :
A two-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size
aspect ratio is 75, as shown in
item 3 of the light truck