check engine GMC SIERRA DENALI 2018 Service Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
374 Vehicle Care .
Removal of the fan shroud,
if equipped.
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
{ Warning
When 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.
Automatic Transmission
Shift Lock Control
Function Check
{ Warning
When 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 off
in each shift lever position.
.
The ignition should turn off only
when the shift lever is in
P (Park).
.
The ignition key should come
out only when the ignition is off.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 375Contact 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.
.
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 0 458 . CautionAllowing the wiper arm to touch
the windshield when no wiper
blade is installed could damage
the windshield. Any damage that
occurs would not be covered by
the vehicle 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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 381Headlamp Wiring An electrical overload may cause
the lamps to go on and off, or in
some cases to remain off. Have the
headlamp wiring checked right away
if the lamps go on and off or
remain off.
Windshield Wipers If the wiper motor overheats due to
heavy snow or ice, the windshield
wipers will stop until the motor cools
and will then restart.
Although the circuit is protected
from electrical overload, overload
due to heavy snow or ice may
cause wiper linkage damage.
Always clear ice and heavy snow
from the windshield before using the
windshield wipers.
If the overload is caused by an
electrical problem and not snow or
ice, be sure to get it fixed. Fuses and Circuit
Breakers The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit
breakers. This greatly reduces the
chance of damage caused by
electrical problems.
{ DangerFuses and circuit breakers are
marked with their ampere rating.
Do not exceed the
specified amperage rating when
replacing fuses and circuit
breakers. Use of an oversized
fuse or circuit breaker can result
in a vehicle fire. You and others
could be seriously injured or
killed.
To check a fuse, look at the
silver-colored band inside the fuse.
If the band is broken or melted,
replace the fuse. Be sure to replace
a bad fuse with a new one of the
identical size and rating. Fuses of the same amperage can
be temporarily borrowed from
another fuse location, if a fuse goes
out. Replace the fuse as soon as
possible.
Engine Compartment
Fuse Block If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
The engine compartment fuse block
is in the engine compartment, on
the driver side of the vehicle.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
426 Vehicle Care
Jump Starting Jump Starting - North
America For an eAssist vehicle, see the
Silverado/Sierra supplement.
For more information about the
vehicle battery, see Battery - North
America 0 369 .
If the vehicle's battery (or batteries)
has run down, you may want to use
another vehicle and some jumper
cables to start your vehicle. Be sure
to use the following steps to do it
safely.
{ Warning
WARNING: Battery posts,
terminals, and related
accessories contain lead and lead
compounds, chemicals known to
the State of California to cause
cancer and birth defects or other
reproductive harm. Batteries also
contain other chemicals known to
(Continued) Warning (Continued) the State of California to cause
cancer. WASH HANDS AFTER
HANDLING. For more information
go to www.P65Warnings.ca.gov/
passenger-vehicle.
See California Proposition
65 Warning 0 343 and the back
cover.
{ WarningBatteries can hurt you. They can
be dangerous because:
.
They contain acid that can
burn you.
.
They contain gas that can
explode or ignite.
.
They contain enough
electricity to burn you.
If you do not follow these steps
exactly, some or all of these
things can hurt you. CautionIgnoring these steps could result
in costly damage to the vehicle
that would not be covered by the
vehicle warranty. Trying to start
the vehicle by pushing or pulling it
will not work, and it could damage
the vehicle.
1. Check the other vehicle.
It must have a 12-volt battery
with a negative ground system.
CautionIf the other vehicle does not have
a 12-volt system with a negative
ground, both vehicles can be
damaged. Only use a vehicle that
has a 12-volt system with a
negative ground for jump starting.
2. If you have a vehicle with a
diesel engine with two
batteries, you should know
before you begin that,
especially in cold weather, you

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
428 Vehicle Care
{ WarningUsing a match near a battery can
cause battery gas to explode.
People have been hurt doing this,
and some have been blinded.
Use a flashlight if you need more
light.
Battery fluid contains acid that
can burn you. Do not get it on
you. If you accidentally get it in
your eyes or on your skin, flush
the place with water and get
medical help immediately.
{ Warning
Fans or other moving engine
parts can injure you badly. Keep
your hands away from moving
parts once the engine is running. 6. Check that the jumper cables
do not have loose or missing
insulation. If they do, you could
get a shock. The vehicles
could be damaged too.
Before you connect the cables,
here are some basic things you
should know. Positive (+) will
go to positive (+) or to a remote
positive (+) terminal if the
vehicle has one. Negative ( − )
will go to a heavy, unpainted
metal engine part or to a
remote negative ( − ) terminal if
the vehicle has one.
Do not connect positive (+) to
negative ( − ) or you will get a
short that would damage the
battery and maybe other parts
too. And do not connect the
negative ( − ) cable to the
negative ( − ) terminal on the
dead battery because this can
cause sparks. 5.3L Shown, 4.3L, 6.0L, 6.2L, and
6.6L Similar
7. Connect the red positive (+)
cable to the positive (+)
terminal of the vehicle with the
dead battery.
8. Do not let the other end touch
metal. Connect it to the
positive (+) terminal of the
good battery. Use a remote
positive (+) terminal if the
vehicle has one.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
432 Vehicle Care Warning (Continued)be injured. Set the parking brake
before shifting the transfer case
to N (Neutral).
To dinghy tow:
1. Position the vehicle being
towed behind the tow vehicle,
facing forward and on a level
surface.
2. Securely attach the vehicle
being towed to the tow vehicle.
3. Apply the parking brake and
start the engine.
4. Shift the transfer case to
N (Neutral). See “ Shifting into
N (Neutral) ” under Four-Wheel
Drive 0 272 . Check that the
vehicle is in N (Neutral) by
shifting the transmission to
R (Reverse) and then to D
(Drive). There should be no
movement of the vehicle while
shifting.
5. Turn the engine off. CautionFailure to disconnect the negative
battery cable or to have it contact
the terminals can cause damage
to the vehicle.
6. Disconnect the negative
battery cable at the battery and
secure the nut and bolt. Cover
the negative battery post with a
non-conductive material to
prevent any contact with the
negative battery terminal.
7. Shift the transmission to
P (Park).
Caution
If the steering column is locked,
vehicle damage may occur.
8. Move the steering wheel to
make sure the steering column
is unlocked. 9. With a foot on the brake pedal,
release the parking brake.
Keep the ignition key in the
towed vehicle in ACC/
ACCESSORY to prevent the
steering column from locking.
Disconnecting the Towed Vehicle
Before disconnecting the towed
vehicle:
1. Park on a level surface.
2. Set the parking brake, then
shift the transmission to
P (Park), and turn the ignition
key off.
3. Connect the battery.
4. Apply the brake pedal.
5. Turn the ignition on with the
engine off. Shift the transfer
case out of N (Neutral) to
Two-Wheel Drive High. See
“ Shifting out of N (Neutral) ”
under Four-Wheel Drive 0 272 .
See your dealer if the transfer
case cannot be shifted out of
N (Neutral).

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
440 Vehicle Care Steering, Suspension, and
Chassis Components Visually inspect steering,
suspension, and chassis
components for damaged, loose,
or missing parts or signs of wear at
least once a year.
Inspect power steering for proper
attachment, connections, binding,
leaks, cracks, chafing, etc.
Visually check constant velocity joint
boots and axle seals for leaks.
1500 Series vehicles, at least every
other oil change lubricate the outer
tie rod ends.
2500/3500 Series vehicles, at least
every other engine oil change
lubricate the upper and lower
control arm ball joints. Control arm
ball joints on 1500 series vehicles
are maintenance-free.
2500/3500 Series vehicles equipped
with steering linkage, at least every
other engine oil change lubricate the
tie rod ball joints, idler arm pivot
shaft bearings, idler arm socket, and
pitman arm socket. CautionLubrication of applicable steering/
suspension points should not be
done unless the temperature is
− 12 °C (10 °F) or higher,
or damage could result.
For an eAssist vehicle, see the
Silverado/Sierra eAssist
supplement.
Body Component Lubrication Lubricate all key lock cylinders,
hood hinges, liftgate hinges, and the
steel fuel door hinge unless the
components are plastic. Applying
silicone grease on weatherstrips
with a clean cloth will make them
last longer, seal better, and not stick
or squeak.
Underbody Maintenance
At least twice a year, spring and fall,
use plain water to flush any
corrosive materials from the
underbody. Take care to thoroughly
clean any areas where mud and other debris can collect. If equipped
with power assist steps, extend
them and then use a high pressure
wash to clean all joints and gaps.
Do not directly power wash the
transfer case and/or front/rear axle
output seals. High pressure water
can overcome the seals and
contaminate the fluid. Contaminated
fluid will decrease the life of the
transfer case and/or axles and
should be replaced.
Sheet Metal Damage If the vehicle is damaged and
requires sheet metal repair or
replacement, make sure the body
repair shop applies anti-corrosion
material to parts repaired or
replaced to restore corrosion
protection.
Original manufacturer replacement
parts will provide the corrosion
protection while maintaining the
vehicle warranty.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
446 Service and Maintenance
Service and
Maintenance General Information General Information . . . . . . . . . . 446
Maintenance Schedule Maintenance Schedule . . . . . . . 448
Special Application Services Special Application
Services . . . . . . . . . . . . . . . . . . . . 453
Additional Maintenance
and Care Additional Maintenance
and Care . . . . . . . . . . . . . . . . . . . . 453
Recommended Fluids,
Lubricants, and Parts Recommended Fluids and
Lubricants . . . . . . . . . . . . . . . . . . . 456
Maintenance Replacement
Parts . . . . . . . . . . . . . . . . . . . . . . . . 458
Maintenance Records
Maintenance Records . . . . . . . . 459 General Information This maintenance section applies to
vehicles with a gasoline engine. For
diesel engine vehicles, see
"Maintenance Schedule" in the
Duramax diesel supplement.
Your vehicle is an important
investment. This section describes
the required maintenance for the
vehicle. Follow this schedule to help
protect against major repair
expenses resulting from neglect or
inadequate maintenance. It may
also help to maintain the value of
the vehicle if it is sold. It is the
responsibility of the owner to have
all required maintenance performed.
Your dealer has trained technicians
who can perform required
maintenance using genuine
replacement parts. They have
up-to-date tools and equipment for
fast and accurate diagnostics. Many
dealers have extended evening and
Saturday hours, courtesy
transportation, and online
scheduling to assist with service
needs. Your dealer recognizes the
importance of providing
competitively priced maintenance
and repair services. With trained
technicians, the dealer is the place
for routine maintenance such as oil
changes and tire rotations and
additional maintenance items like
tires, brakes, batteries, and wiper
blades.
CautionDamage caused by improper
maintenance can lead to costly
repairs and may not be covered
by the vehicle warranty.
Maintenance intervals, checks,
inspections, recommended fluids,
and lubricants are important to
keep the vehicle in good working
condition.
Do not have chemical flushes that
are not approved by GM
performed on the vehicle. The
use of flushes, solvents, cleaners,
or lubricants that are not
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
448 Service and Maintenance
Maintenance
Schedule Owner Checks and Services At Each Fuel Stop
.
Check the engine oil level. See
Engine Oil 0 350 .
Once a Month
.
Check the tire inflation
pressures. See Tire Pressure
0 397 .
.
Inspect the tires for wear. See
Tire Inspection 0 404 .
.
Check the windshield washer
fluid level. See Washer Fluid
0 366 .
Engine Oil Change When the CHANGE ENGINE OIL
SOON message displays, have the
engine oil and filter changed within
the next 1 000 km/600 mi. If driven
under the best conditions, the
engine oil life system may not
indicate the need for vehicle service
for up to a year. The engine oil and filter must be changed at least once
a year and the oil life system must
be reset. Your trained dealer
technician can perform this work.
If the engine oil life system is reset
accidentally, service the vehicle
within 5 000 km/3,000 mi since the
last service. Reset the oil life
system when the oil is changed.
See Engine Oil Life System 0 353 .
Passenger Compartment Air
Filter The passenger compartment air
filter removes dust, pollen, and
other airborne irritants from outside
air that is pulled into the vehicle.
The filter should be replaced as part
of routine scheduled maintenance.
Inspect the passenger compartment
air filter every 36 000 km/
22,500 miles or two years,
whichever comes first. Replace if
necessary. More frequent
replacement may be needed if the
vehicle is driven in areas with heavy
traffic, areas with poor air quality,
or areas with high dust levels. Replacement may also be needed if
there is a reduction in air flow,
excessive window fogging, or odors.
Tire Rotation and Required
Services Every 12 000 km/
7,500 mi Rotate the tires, if recommended for
the vehicle, and perform the
following services. See Tire
Rotation 0 405 .
.
Check engine oil level and oil
life percentage. If needed,
change engine oil and filter, and
reset oil life system. See Engine
Oil 0 350 and Engine Oil Life
System 0 353 .
.
Check engine coolant level. See
Cooling System 0 359 .
.
Check windshield washer fluid
level. See Washer Fluid 0 366 .
.
Visually inspect windshield wiper
blades for wear, cracking,
or contamination. See Exterior
Care 0 435 . Replace worn or
damaged wiper blades. See
Wiper Blade Replacement
0 375 .

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Service and Maintenance 449.
Check tire inflation pressures.
See Tire Pressure 0 397 .
.
Inspect tire wear. See Tire
Inspection 0 404 .
.
Visually check for fluid leaks.
.
Inspect engine air cleaner filter.
See Engine Air Cleaner/Filter
0 358 .
.
Inspect brake system. See
Exterior Care 0 435 .
.
Visually inspect steering,
suspension, and chassis
components for damaged, loose,
or missing parts or signs of wear
at least once a year. See
Exterior Care 0 435 . Lubricate
the suspension and steering
components at least every other
oil change. (If equipped with
grease fittings)
.
Check restraint system
components. See Safety System
Check 0 75 . .
Visually inspect fuel system for
damage or leaks.
.
Visually inspect exhaust system
and nearby heat shields for
loose or damaged parts.
.
Lubricate body components. See
Exterior Care 0 435 .
.
Check starter switch. See Starter
Switch Check 0 374 .
.
Check automatic transmission
shift lock control function. See
Automatic Transmission Shift
Lock Control Function Check
0 374 .
.
Check ignition transmission lock.
See Ignition Transmission Lock
Check 0 374 .
.
Check parking brake and
automatic transmission park
mechanism. See Park Brake and
P (Park) Mechanism Check
0 375 . .
Check accelerator pedal for
damage, high effort, or binding.
Replace if needed.
.
Visually inspect gas strut for
signs of wear, cracks, or other
damage. Check the hold open
ability of the strut. If the hold
open ability is low, service the
gas strut. See Gas Strut(s)
0 376 .
.
Inspect sunroof track and seal,
if equipped. See Sunroof 0 55 .
.
Verify spare tire key lock
operation and lubricate as
needed. See Tire Changing
0 415 .