transmission GMC SIERRA DENALI 2018 Workshop Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
316 Driving and Operating 1500/2500/3500 Series Pickups – SAE J2807 Compliant
Vehicle Axle Ratio Maximum Trailer
Weight (c) GCWR (a)
6.2L V8 – Gooseneck/Fifth-Wheel
Trailer 3.42 4 627 kg (10,200 lb) 8 029 kg (17,700 lb)
1500 Series 4WD Crew Cab Short Box (b)
4.3L V6 3.42 3 175 kg (7,000 lb) 5 806 kg (12,800 lb)
5.3L V8 3.08 2 767 kg (6,100 lb) 5 443 kg (12,000 lb)
5.3L V8 3.42 4 128 kg (9,100 lb) 6 804 kg (15,000 lb)
5.3L V8, 8-speed automatic
transmission with Enhanced
Towing Package 3.42 4 853 kg (10,700 lb) 7 575 kg (16,700 lb)
5.3L V8 3.73 4 853 kg (10,700 lb) 7 575 kg (16,700 lb)
6.2L V8 3.23 4 128 kg (9,100 lb) 6 804 kg (15,000 lb)
6.2L V8 3.42 5 307 kg (11,700 lb) 8 029 kg (17,700 lb)
1500 Series 4WD Regular Cab Long Box
4.3L V6 – Conventional Trailer 3.42 3 357 kg (7,400 lb) 5 806 kg (12,800 lb)
4.3L V6 – Gooseneck/Fifth Wheel 3.42 3 311 kg (7,300 lb) 5 806 kg (12,800 lb)
5.3L V8 – Conventional Trailer 3.08 2 948 kg (6,500 lb) 5 443 kg (12,000 lb)
5.3L V8 – Gooseneck/Fifth Wheel 3.08 2 903 kg (6,400 lb) 5 443 kg (12,000 lb)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
330 Driving and Operating .
Black: Ground
Be sure to consult the aftermarket
electric brake controller owner ’ s
manual to determine wire color
coding of the electric trailer brake
controller. The wire colors on the
brake controller may be different
from the vehicle.
The electric trailer brake controller
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 0 271 .
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 0 307 . 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.
Operating 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.

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 Proposition
65 Warning . . . . . . . . . . . . . . . . . 343
California Perchlorate
Materials Requirements . . . . . 343
Accessories and
Modifications . . . . . . . . . . . . . . . . 343
Vehicle Checks Doing Your Own
Service 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 and
Wiring . . . . . . . . . . . . . . . . . . . . . . . 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. See
Jump Starting - North America
0 426 .
2. Battery - North America 0 369 .
3. Coolant Surge Tank and
Pressure Cap. See Cooling
System 0 359 .
4. Engine Air Cleaner/Filter 0 358 .
5. Automatic Transmission
Dipstick (If Equipped). See
“ How to Check Automatic
Transmission Fluid ” under
Automatic Transmission Fluid
(6-Speed Transmission) 0 354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357 . 6. Remote Negative ( – ) Location.
See Jump Starting - North
America 0 426 .
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 0 350 .
9. Engine Oil Dipstick. See
“ Checking Engine Oil ” under
Engine Oil 0 350 . 10. Brake Fluid Reservoir. See
Brake Fluid 0 368 .
11. Windshield Washer Fluid
Reservoir. See “ Adding Washer
Fluid ” under Washer Fluid
0 366 .
12. Engine Compartment Fuse
Block 0 381 .

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
348 Vehicle Care 1. Positive (+) Terminal. See
Jump Starting - North America
0 426 .
2. Battery - North America 0 369 .
3. Coolant Surge Tank and
Pressure Cap. See Cooling
System 0 359 .
4. Engine Air Cleaner/Filter 0 358 .
5. Automatic Transmission
Dipstick (If Equipped). See
“ How to Check Automatic
Transmission Fluid ” under
Automatic Transmission Fluid
(6-Speed Transmission) 0 354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357 . 6. Remote Negative ( – ) Location
(Out of View). See Jump
Starting - North America 0 426 .
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 0 350 .
9. Engine Oil Dipstick. See
“ Checking Engine Oil ” under
Engine Oil 0 350 . 10. Windshield Washer Fluid
Reservoir. See “ Adding Washer
Fluid ” under Washer Fluid
0 366 .
11. Brake Fluid Reservoir. See
Brake Fluid 0 368 .
12. Engine Compartment Fuse
Block 0 381 .

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
350 Vehicle Care 1. Positive (+) Terminal. See
Jump Starting - North America
0 426 .
2. Battery - North America 0 369 .
3. Coolant Surge Tank and
Pressure Cap. See Cooling
System 0 359 .
4. Engine Air Cleaner/Filter 0 358 .
5. Automatic Transmission
Dipstick (If Equipped). See
“ How to Check Automatic
Transmission Fluid ” under
Automatic Transmission Fluid
(6-Speed Transmission) 0 354
or Automatic Transmission
Fluid (8-Speed Transmission)
0 357 .
6. Engine Oil Dipstick. See
“ Checking Engine Oil ” under
Engine Oil 0 350 .
7. Engine Oil Fill Cap. See “ When
to Add Engine Oil ” under
Engine Oil 0 350 .
8. Engine Cooling Fan (Out of
View). See Cooling System
0 359 . 9. Remote Negative ( – ) Location.
See Jump Starting - North
America 0 426 .
10. Power Steering Fluid
Reservoir. See Power Steering
Fluid (1500 Series) 0 365 or
Power Steering Fluid (2500/
3500 Series) 0 365 .
11. Windshield Washer Fluid
Reservoir. See “ Adding Washer
Fluid ” under Washer Fluid
0 366 .
12. Brake Fluid Reservoir. See
Brake Fluid 0 368 .
13. Auxiliary Battery (If Equipped).
See Battery - North America
0 369 .
14. Engine Compartment Fuse
Block 0 381 .
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 0 353 .
.
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
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) 0 160 or Driver
Information Center (DIC) (Base
Level Cluster) 0 158 .
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) 0 160 or Driver
Information Center (DIC) (Base
Level Cluster) 0 158 .
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 355Caution (Continued)automatic transmission fluid listed
in Recommended Fluids and
Lubricants 0 456 .
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 0 456 .
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) 0 160 or Driver
Information Center (DIC) (Base
Level Cluster) 0 158 .
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 transmission
dipstick at the rear of the
engine compartment, on the
passenger side of the vehicle.
See Engine Compartment
Overview 0 345 .
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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 3571. Locate the transmission
dipstick at the rear of the
engine compartment, on the
passenger side of the vehicle.
See Engine Compartment
Overview 0 345 .
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. Safe operating level is within
the HOT cross hatch band on
the dipstick. If the fluid level is
not within the HOT band, and
the transmission temperature is
between 71 °C and 93 °C
(160 °F and 200 °F), add or
drain fluid as necessary to
bring the level into the HOT
band. If the fluid level is low,
add only enough fluid to bring
the level into the HOT band.
It does not take much fluid,
generally less than 0.5 L (1 pt).
Do not overfill.
6. 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.
Consistency of Readings
Always check the fluid level at least
twice using the procedure described
previously. Consistency (repeatable
readings) is important to maintaining
proper fluid level. If readings are still
inconsistent, contact the dealer. Automatic Transmission
Fluid (8-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. This vehicle is not
equipped with a transmission fluid
level dipstick. There is a special
procedure for checking and
changing the transmission fluid in
these vehicles. Because this
procedure is difficult, this should be
done at the dealer. Contact the
dealer for additional information or
the procedure can be found in the
service manual. See Service
Publications Ordering Information
0 474 .