check engine GMC SIERRA 2018 Owner's Guide

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
336 Driving and Operating
Warning (Continued)
(20-25 mph) and fully apply
the manual trailer brake
apply lever. Also check that
the trailer brake lamps and
other lamps are functioning
correctly.
. If the trailer brakes are not
operating properly at any
time, or if a DIC message
indicates problems with the
trailer connections or trailer
brakes, carefully pull the
vehicle over to the side of
the road when traffic
conditions allow.
Conversions and
Add-Ons
Add-On Electrical
Equipment
{Warning
The Data Link Connector (DLC) is
used for vehicle service
and Emission Inspection/
Maintenance testing. See
Malfunction Indicator Lamp
(Check Engine Light) 0150.
A device connected to the DLC —
such as an aftermarket fleet or
driver-behavior tracking device —
may interfere with vehicle
systems. This could affect vehicle
operation and cause a crash.
Such devices may also access
information stored in the vehicle’s
systems.
Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
vehicle warranty. Always check
with your dealer before adding
electrical equipment.
Add-on equipment can drain the
vehicle's 12-volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle 090 and Adding Equipment
to the Airbag-Equipped Vehicle
0 90.
For information on wiring auxiliary
switches, see www.gmupfitter.com
or contact your dealer.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 341
Vehicle Care
General Information
General Information . . . . . . . . . . 342
California Proposition65 Warning . . . . . . . . . . . . . . . . . 343
California Perchlorate Materials Requirements . . . . . 343
Accessories and Modifications . . . . . . . . . . . . . . . . 343
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 344
Hood . . . . . . . . . . . . . . . . . . . . . . . . . 344
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . . 345
Engine Oil . . . . . . . . . . . . . . . . . . . . 350
Engine Oil Life System . . . . . . . 353
Automatic Transmission Fluid (6-Speed Transmission) . . . . . 354
Automatic Transmission Fluid (8-Speed Transmission) . . . . . 357
Engine Air Cleaner/Filter . . . . . . 358
Cooling System . . . . . . . . . . . . . . 359
Engine Overheating . . . . . . . . . . 363
Overheated Engine Protection Operating Mode . . . . . . . . . . . . . 364
Engine Fan . . . . . . . . . . . . . . . . . . . 365 Power Steering Fluid (1500
Series) . . . . . . . . . . . . . . . . . . . . . . 365
Power Steering Fluid (2500/ 3500 Series) . . . . . . . . . . . . . . . . 365
Washer Fluid . . . . . . . . . . . . . . . . . 366
Brakes . . . . . . . . . . . . . . . . . . . . . . . 367
Brake Fluid . . . . . . . . . . . . . . . . . . . 368
Battery - North America . . . . . . 369
Four-Wheel Drive . . . . . . . . . . . . . 370
Front Axle . . . . . . . . . . . . . . . . . . . . 370
Rear Axle . . . . . . . . . . . . . . . . . . . . 371
Noise Control System . . . . . . . . 373
Starter Switch Check . . . . . . . . . 374
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 374
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . . . 374
Park Brake and P (Park) Mechanism Check . . . . . . . . . . 375
Wiper Blade Replacement . . . . 375
Windshield Replacement . . . . . 376
Gas Strut(s) . . . . . . . . . . . . . . . . . . 376
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . . . 377
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 378
Halogen Bulbs . . . . . . . . . . . . . . . . 378 High Intensity Discharge (HID)
Lighting . . . . . . . . . . . . . . . . . . . . . 378
LED Lighting . . . . . . . . . . . . . . . . . 378
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . . . 378
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 380
Electrical System
High Voltage Devices andWiring . . . . . . . . . . . . . . . . . . . . . . . 380
Electrical System Overload . . . 380
Fuses and Circuit Breakers . . . 381
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 381
Instrument Panel Fuse Block (Right) . . . . . . . . . . . . . . . . . . . . . . 385
Instrument Panel Fuse Block (Left) . . . . . . . . . . . . . . . . . 386
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 389
All-Season Tires . . . . . . . . . . . . . . 389
Winter Tires . . . . . . . . . . . . . . . . . . 390
Low-Profile Tires . . . . . . . . . . . . . 390
All-Terrain Tires . . . . . . . . . . . . . . . 391
Tire Sidewall Labeling . . . . . . . . 391
Tire Designations . . . . . . . . . . . . . 393

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
346 Vehicle Care
1. Positive (+) Terminal. SeeJump Starting - North America
0426.
2. Battery - North America 0369.
3. Coolant Surge Tank and Pressure Cap. See Cooling
System 0359.
4. Engine Air Cleaner/Filter 0358.
5. Automatic Transmission Dipstick (If Equipped). See
“How to Check Automatic
Transmission Fluid” under
Automatic Transmission Fluid
(6-Speed Transmission) 0354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357. 6. Remote Negative (–) Location.
See Jump Starting - North
America 0426.
7. Engine Cooling Fans (Out of View). See Cooling System
0 359.
8. Engine Oil Fill Cap. See “When
to Add Engine Oil” under
Engine Oil 0350.
9. Engine Oil Dipstick. See “Checking Engine Oil” under
Engine Oil 0350. 10. Brake Fluid Reservoir. See
Brake Fluid 0368.
11. Windshield Washer Fluid Reservoir. See “Adding Washer
Fluid” under Washer Fluid
0 366.
12. Engine Compartment Fuse
Block 0381.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
348 Vehicle Care
1. Positive (+) Terminal. SeeJump Starting - North America
0426.
2. Battery - North America 0369.
3. Coolant Surge Tank and Pressure Cap. See Cooling
System 0359.
4. Engine Air Cleaner/Filter 0358.
5. Automatic Transmission Dipstick (If Equipped). See
“How to Check Automatic
Transmission Fluid” under
Automatic Transmission Fluid
(6-Speed Transmission) 0354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357. 6. Remote Negative (–) Location
(Out of View). See Jump
Starting - North America 0426.
7. Engine Cooling Fans (Out of View). See Cooling System
0 359.
8. Engine Oil Fill Cap. See “When
to Add Engine Oil” under
Engine Oil 0350.
9. Engine Oil Dipstick. See “Checking Engine Oil” under
Engine Oil 0350. 10. Windshield Washer Fluid
Reservoir. See “Adding Washer
Fluid” under Washer Fluid
0 366.
11. Brake Fluid Reservoir. See Brake Fluid 0368.
12. Engine Compartment Fuse
Block 0381.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
350 Vehicle Care
1. Positive (+) Terminal. SeeJump Starting - North America
0426.
2. Battery - North America 0369.
3. Coolant Surge Tank and Pressure Cap. See Cooling
System 0359.
4. Engine Air Cleaner/Filter 0358.
5. Automatic Transmission Dipstick (If Equipped). See
“How to Check Automatic
Transmission Fluid” under
Automatic Transmission Fluid
(6-Speed Transmission) 0354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357.
6. Engine Oil Dipstick. See “Checking Engine Oil” under
Engine Oil 0350.
7. Engine Oil Fill Cap. See “When
to Add Engine Oil” under
Engine Oil 0350.
8. Engine Cooling Fan (Out of View). See Cooling System
0 359. 9. Remote Negative (–) Location.
See Jump Starting - North
America 0426.
10. Power Steering Fluid Reservoir. See Power Steering
Fluid (1500 Series) 0365 or
Power Steering Fluid (2500/
3500 Series) 0365.
11. Windshield Washer Fluid Reservoir. See “Adding Washer
Fluid” under Washer Fluid
0 366.
12. Brake Fluid Reservoir. See Brake Fluid 0368.
13. Auxiliary Battery (If Equipped). SeeBattery - North America
0 369.
14. Engine Compartment Fuse
Block 0381.
If the vehicle has a diesel engine
and/or an Allison Transmission, see
the Duramax diesel supplement.
For an eAssist vehicle, see the
Silverado/Sierra supplement.Engine Oil
For diesel engine vehicles, see
“Engine Oil” in the Duramax diesel
supplement.
To ensure proper engine
performance and long life, careful
attention must be paid to engine oil.
Following these simple, but
important steps will help protect
your investment:
. Use engine oil approved to the
proper specification and of the
proper viscosity grade. See
“Selecting the Right Engine Oil”
in this section.
. Check the engine oil level
regularly and maintain the
proper oil level. See “Checking
Engine Oil” and“When to Add
Engine Oil” in this section.
. Change the engine oil at the
appropriate time. See Engine Oil
Life System 0353.
. Always dispose of engine oil
properly. See “What to Do with
Used Oil” in this section.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 351
Checking Engine Oil
Check the engine oil level regularly,
every 650 km (400 mi), especially
prior to a long trip. The engine oil
dipstick handle is a loop. See
Engine Compartment Overview
0345 for the location.
{Warning
The engine oil dipstick handle
may be hot; it could burn you.
Use a towel or glove to touch the
dipstick handle.
If a low oil Driver Information Center
(DIC) message displays, check the
oil level.
Follow these guidelines:
. To get an accurate reading, park
the vehicle on level ground.
Check the engine oil level after
the engine has been off for at
least two hours. Checking the
engine oil level on steep grades
or too soon after engine shutoff
can result in incorrect readings.
Accuracy improves when checking a cold engine prior to
starting. Remove the dipstick
and check the level.
. If unable to wait two hours, the
engine must be off for at least
15 minutes if the engine is
warm, or at least 30 minutes if
the engine is not warm. Pull out
the dipstick, wipe it with a clean
paper towel or cloth, then push it
back in all the way. Remove it
again, keeping the tip down, and
check the level.
When to Add Engine Oil
V6 Engine
V8 Engines
If the oil is below the cross-hatched
area at the tip of the dipstick and
the engine has been off for at least
15 minutes, add 1 L (1 qt) of the
recommended oil and then recheck
the level. See “Selecting the Right
Engine Oil” later in this section for
an explanation of what kind of oil to
use. For engine oil crankcase
capacity, see Capacities and
Specifications 0461.
Caution
Do not add too much oil. Oil
levels above or below the
acceptable operating range
shown on the dipstick are harmful
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 353
Engine Oil Additives/Engine
Oil Flushes
Do not add anything to the oil. The
recommended oils meeting the
dexos1 specification are all that is
needed for good performance and
engine protection.
Engine oil system flushes are not
recommended and could cause
engine damage not covered by the
vehicle warranty.
What to Do with Used Oil
Used engine oil contains certain
elements that can be unhealthy for
your skin and could even cause
cancer. Do not let used oil stay on
your skin for very long. Clean your
skin and nails with soap and water,
or a good hand cleaner. Wash or
properly dispose of clothing or rags
containing used engine oil. See the
manufacturer's warnings about the
use and disposal of oil products.Used oil can be a threat to the
environment. If you change your
own oil, be sure to drain all the oil
from the filter before disposal. Never
dispose of oil by putting it in the
trash or pouring it on the ground,
into sewers, or into streams or
bodies of water. Recycle it by taking
it to a place that collects used oil.
Engine Oil Life System
When to Change Engine Oil
This vehicle has a computer system
that indicates when to change the
engine oil and filter. This is based
on a combination of factors which
include engine revolutions, engine
temperature, and miles driven.
Based on driving conditions, the
mileage at which an oil change is
indicated can vary considerably. For
the oil life system to work properly,
the system must be reset every time
the oil is changed.
On some vehicles, when the system
has calculated that oil life has been
diminished, a CHANGE ENGINE
OIL SOON message comes on toindicate that an oil change is
necessary. Change the oil as soon
as possible within the next 1 000 km
(600 mi). It is possible that, if driving
under the best conditions, the oil life
system might indicate that an oil
change is not necessary for up to a
year. The engine oil and filter must
be changed at least once a year
and, at this time, the system must
be reset. For vehicles without the
CHANGE ENGINE OIL SOON
message, an oil change is needed
when the OIL LIFE REMAINING
percentage is near 0%. Your dealer
has trained service people who will
perform this work and reset the
system. It is also important to check
the oil regularly over the course of
an oil drain interval and keep it at
the proper level.
If the system is ever reset
accidentally, the oil must be
changed at 5 000 km (3,000 mi)
since the last oil change.
Remember to reset the oil life
system whenever the oil is changed.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
354 Vehicle Care
How to Reset the Engine Oil
Life System
Reset the system whenever the
engine oil is changed so that the
system can calculate the next
engine oil change. Always reset the
engine oil life to 100% after every oil
change. It will not reset itself. To
reset the engine oil life system:1. Display the OIL LIFE REMAINING on the DIC. If the
vehicle does not have DIC
buttons, the vehicle must be in
P (Park) to access this display.
See Driver Information Center
(DIC) (Uplevel and Denali
Cluster) 0160 orDriver
Information Center (DIC) (Base
Level Cluster) 0158.
2. Press and hold
V, or the trip
odometer reset stem if the
vehicle does not have DIC
buttons, for several seconds.
The oil life will change
to 100%. The oil life system can also be reset
as follows:
1. Display the OIL LIFE REMAINING on the DIC.
See Driver Information Center
(DIC) (Uplevel and Denali
Cluster) 0160 orDriver
Information Center (DIC) (Base
Level Cluster) 0158.
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
not be covered by the vehicle
warranty. Always use the (Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 355
Caution (Continued)
automatic transmission fluid listed
inRecommended Fluids and
Lubricants 0456.
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule
0 448. Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants 0456.
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
system parts, starting a fire. Too
little fluid could cause the (Continued)
Caution (Continued)
transmission to overheat. Be sure
to get an accurate reading if
checking the transmission fluid.
Before checking the fluid level,
prepare the vehicle: 1. Start the engine and park the vehicle on a level surface.
Keep the engine running.
2. Apply the parking brake and place the shift lever in P (Park).
3. With your foot on the brake pedal, move the shift lever
through each gear range,
pausing for about
three seconds in each range.
Then, move the shift lever back
to P (Park).
4. Allow the engine to idle (500– 800 rpm) for at least
one minute. Slowly release the
brake pedal. 5. Keep the engine running and
check the transmission fluid
temperature on the Driver
Information Center (DIC).
See Driver Information Center
(DIC) (Uplevel and Denali
Cluster) 0160 orDriver
Information Center (DIC) (Base
Level Cluster) 0158.
6. Using the transmission fluid temperature reading, determine
and perform the appropriate
check procedure. If the
transmission fluid temperature
reading is not within the
required temperature ranges,
allow the vehicle to cool,
or operate the vehicle until the
appropriate transmission fluid
temperature is reached.
Cold Check Procedure
Use this procedure only as a
reference to determine if the
transmission has enough fluid to be
operated safely until a hot check
procedure can be made. The hot
check procedure is the most
accurate method to check the fluid
level. Perform the hot check

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
356 Vehicle Care
procedure at the first opportunity.
Use this cold check procedure to
check fluid level when the
transmission temperature is
between 27 °C and 32 °C (80 °F and
90 °F).
1. Locate the transmissiondipstick at the rear of the
engine compartment, on the
passenger side of the vehicle.
See Engine Compartment
Overview 0345.
2. Flip the handle up, then pull out the dipstick and wipe it with a
clean rag or paper towel.
3. Install the dipstick by pushing it back in all the way; wait
three seconds, and then pull it
back out again. 4. Check both sides of the
dipstick and read the lower
level. Repeat the check
procedure to verify the reading.
5. If the fluid level is below the
COLD check band, add only
enough fluid as necessary to
bring the level into the COLD
band. It does not take much
fluid, generally less than 0.5 L
(1 pt). Do not overfill.
6. Perform a hot check at the first opportunity after the
transmission reaches a normal
operating temperature between
71 °C to 93 °C (160 °F to
200 °F). 7. If the fluid level is in the
acceptable range, push the
dipstick back in all the way,
then flip the handle down to
lock the dipstick in place.
Hot Check Procedure
Use this procedure to check the
transmission fluid level when the
transmission fluid temperature is
between 71 °C and 93 °C (160 °F
and 200 °F).
The hot check is the most accurate
method to check the fluid level. The
hot check should be performed at
the first opportunity in order to verify
the cold check. The fluid level rises
as fluid temperature increases, so it
is important to ensure the
transmission temperature is within
range.