
GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
280 Driving and Operating Leaving the Vehicle with the
Engine Running
{ WarningIt can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear – not in
N (Neutral).
And, if you leave the vehicle with
the engine running, it could
overheat and even catch fire. You
or others could be injured. Do not
leave the vehicle with the engine
running unless you have to.
If you have to leave the vehicle with
the engine running, be sure the
vehicle is in P (Park) and the parking brake is firmly set before
you leave it. After you move the shift
lever into P (Park), hold the regular
brake pedal down. Then, see if you
can move the shift lever away from
P (Park) without first pulling it toward
you. If you can, it means that the
shift lever was not fully locked into
P (Park).
Torque Lock If you are parking on a hill and you
do not shift the transmission into
P (Park) properly, the weight of the
vehicle may put too much force on
the parking pawl in the
transmission. You may find it difficult
to pull the shift lever out of P (Park).
This is called torque lock. To
prevent torque lock, set the parking
brake and then shift into P (Park)
properly before you leave the driver
seat. To find out how, see Shifting
Into Park 0 279 .
When you are ready to drive, move
the shift lever out of P (Park) before
you release the parking brake.
If torque lock does occur, you may
need to have another vehicle push
yours a little uphill to take some of the pressure from the parking pawl
in the transmission. You will then be
able to pull the shift lever out of
P (Park).
Shifting out of Park This vehicle is equipped with an
electronic shift lock release system.
The shift lock release is
designed to:
.
Prevent ignition key removal
unless the shift lever is in
P (Park).
.
Prevent movement of the shift
lever out of P (Park), unless the
ignition is in ON/RUN and the
regular brake pedal is applied.
The shift lock release is always
functional except in the case of an
uncharged or low voltage (less than
9 volt) battery.
If the vehicle has an uncharged
battery or a battery with low voltage,
try charging or jump starting the
battery. See Jump Starting - North
America 0 435 .

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
342 Driving and Operating pickups. Trailer pin box extensions
and sliding fifth-wheel hitch
assemblies can help this condition.
There should be at least 15 cm (6 in)
of clearance between the top of the
pickup box and the bottom of the
trailer shelf that extends over
the box.
Safety Chains Always attach chains between the
vehicle and the trailer. Cross the
safety chains under the tongue of
the trailer to help prevent the tongue
from contacting the road if it
becomes separated from the hitch.
Instructions about safety chains
may be provided by the hitch
manufacturer or by the trailer
manufacturer. If the trailer being
towed weighs up to 2 271 kg
(5,000 lb) with a factory-installed
step bumper, safety chains may be
attached to the attaching points on
the bumper; otherwise, safety
chains should be attached to holes
on the trailer hitch platform. Always
leave just enough slack so the
combination can turn. Never allow
safety chains to drag on the ground. Trailer Brakes A loaded trailer that weighs more
than 900 kg (2,000 lb) must be
equipped with its own brake system,
with brakes working on all axles.
Trailer braking equipment
conforming to Canadian Standards
Association (CSA) requirement
CAN3-D313, or its equivalent, is
recommended.
State and local regulations may also
require the trailer to have its own
braking system if loaded above a
certain threshold. These
requirements vary from state to
state.
Read and follow the instructions for
the trailer brakes so they are
installed, adjusted, and maintained
properly.
Do not tap into the vehicle's
hydraulic brake system.
Auxiliary Battery
The auxiliary battery provision can
be used to supply electrical power
to additional equipment that may be
added, such as a slide-in camper. If equipped, this relay will be on the
driver side of the vehicle, next to the
underhood electrical center.
Be sure to follow the proper
installation instructions included with
any electrical equipment that is
installed.
CautionLeaving electrical equipment on
for extended periods will drain the
battery. Always turn off electrical
equipment when not in use and
do not use equipment that
exceeds the maximum amperage
rating of 30 amps for the auxiliary
battery provision.
Trailer Wiring Harness The vehicle is equipped with one of
the following wiring harnesses for
towing a trailer or hauling a slide-in
camper.
Basic Trailer Wiring
All regular, double cab, and crew
cab pickups have a seven-wire
trailer towing harness.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
Driving and Operating 343Use only a round, seven-wire
connector with flat blade terminals
meeting SAE J2863 specifications
for proper electrical connectivity.
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
Package
For vehicles equipped with
heavy-duty trailering, the harness
connector is mounted in the bumper. For vehicles with the fifth wheel/
gooseneck trailer package, the
harness connector is mounted on
the inside of the pickup bed behind
the rear wheel.
The seven-wire harness contains
the following trailer circuits:
.
Green/Violet: Right Stop/Turn
Signal
.
Yellow/Gray: Left Stop/Turn
Signal
.
Gray/Brown: Taillamps/Parking
Lamps
.
White: Ground
.
White/Green: Back-up Lamps .
Red/Green: Battery Feed
.
Dark Blue: Trailer Brake
To help charge a remote
(non-vehicle) battery, press the Tow/
Haul Mode button at the end of the
shift lever. If the trailer is too light for
Tow/Haul Mode, turn on the
headlamps to help charge the
battery.
Camper/Fifth-Wheel Trailer Wiring
Package
For vehicles without the fifth wheel/
gooseneck tralier package,
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: Right Stop/Turn
Signal
.
Yellow/Gray: Left Stop/Turn
Signal
.
Gray/Brown: Taillamps/Parking
Lamps

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
344 Driving and Operating .
White: Ground
.
White/Green: Back-up Lamps
.
Red/Green: Battery Feed
.
Dark Blue: Trailer Brake
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 0 288 .
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 0 323 . 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

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
350 Driving and Operating
Conversions and
Add-Ons Add-On Electrical
Equipment
{ WarningThe Data Link Connector (DLC) is
used for vehicle service and
Emission Inspection/Maintenance
testing. See Malfunction Indicator
Lamp (Check Engine Light) 0 144
. 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. CautionSome 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 0 85 and Adding Equipment
to the Airbag-Equipped Vehicle
0 86 .
For information on wiring auxiliary
switches, see www.gmupfitter.com
or contact your dealer. Adding a Snow Plow or
Similar Equipment CautionDo not exceed 72 km/h (45 mph)
with a snow plow mounted to the
vehicle. The vehicle could
overheat and be damaged.
Before installing a snow plow on the
vehicle, follow these guidelines:
CautionIf the vehicle does not have the
snow plow prep package, RPO
VYU, adding a plow can damage
the vehicle, and the repairs would
not be covered by the vehicle
warranty. Unless the vehicle was
built to carry a snow plow, do not
add one to the vehicle. If the
vehicle has RPO VYU, then the
payload the vehicle can carry will
be reduced when a snow plow is
installed. The vehicle can be
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
Vehicle Care 355
Vehicle Care General Information General Information . . . . . . . . . . 356
California Proposition
65 Warning . . . . . . . . . . . . . . . . . 357
California Perchlorate
Materials Requirements . . . . . 357
Accessories and
Modifications . . . . . . . . . . . . . . . . 357
Vehicle Checks Doing Your Own
Service Work . . . . . . . . . . . . . . . 358
Hood . . . . . . . . . . . . . . . . . . . . . . . . . 358
Engine Compartment
Overview . . . . . . . . . . . . . . . . . . . . 359
Engine Oil . . . . . . . . . . . . . . . . . . . . 364
Engine Oil Life System . . . . . . . 367
Automatic Transmission Fluid
(6 Speed Transmission) . . . . . 368
Automatic Transmission Fluid
(8 Speed Transmission) . . . . . 371
Engine Air Cleaner/Filter . . . . . . 371
Cooling System . . . . . . . . . . . . . . 372
Engine Coolant . . . . . . . . . . . . . . . 374
Engine Overheating . . . . . . . . . . 376
Overheated Engine Protection
Operating Mode . . . . . . . . . . . . . 378
Engine Fan . . . . . . . . . . . . . . . . . . . 378 Power Steering Fluid (1500
Series) . . . . . . . . . . . . . . . . . . . . . . 379
Power Steering Fluid (2500/
3500 Series) . . . . . . . . . . . . . . . . 379
Washer Fluid . . . . . . . . . . . . . . . . . 380
Brakes . . . . . . . . . . . . . . . . . . . . . . . 381
Brake Fluid . . . . . . . . . . . . . . . . . . . 381
Battery - North America . . . . . . 383
Four-Wheel Drive . . . . . . . . . . . . . 383
Front Axle . . . . . . . . . . . . . . . . . . . . 384
Rear Axle . . . . . . . . . . . . . . . . . . . . 385
Noise Control System . . . . . . . . 386
Starter Switch Check . . . . . . . . . 387
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 387
Ignition Transmission Lock
Check . . . . . . . . . . . . . . . . . . . . . . . 388
Park Brake and P (Park)
Mechanism Check . . . . . . . . . . 388
Wiper Blade Replacement . . . . 388
Glass Replacement . . . . . . . . . . 389
Headlamp Aiming Headlamp Aiming . . . . . . . . . . . . 389
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 389
Halogen Bulbs . . . . . . . . . . . . . . . . 389
High Intensity Discharge (HID)
Lighting . . . . . . . . . . . . . . . . . . . . . 390 LED Lighting . . . . . . . . . . . . . . . . . 390
Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . . . 390
Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 391
Replacement Bulbs . . . . . . . . . . . 392
Electrical System High Voltage Devices and
Wiring . . . . . . . . . . . . . . . . . . . . . . . 392
Electrical System Overload . . . 392
Fuses . . . . . . . . . . . . . . . . . . . . . . . . 393
Engine Compartment Fuse
Block . . . . . . . . . . . . . . . . . . . . . . . . 393
Instrument Panel Fuse Block
(Right) . . . . . . . . . . . . . . . . . . . . . . 396
Instrument Panel Fuse
Block (Left) . . . . . . . . . . . . . . . . . 398
Wheels and Tires Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 400
All-Season Tires . . . . . . . . . . . . . . 401
Winter Tires . . . . . . . . . . . . . . . . . . 401
Low-Profile Tires . . . . . . . . . . . . . 402
All-Terrain Tires . . . . . . . . . . . . . . . 402
Tire Sidewall Labeling . . . . . . . . 402
Tire Designations . . . . . . . . . . . . . 405
Tire Terminology and
Definitions . . . . . . . . . . . . . . . . . . 406

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
Vehicle Care 357
California Proposition
65 Warning WARNING: Most motor vehicles,
including this one, as well as many
of its service parts and fluids,
contain and/or emit chemicals
known to the State of California to
cause cancer and birth defects or
other reproductive harm. Engine
exhaust, many parts and systems,
many fluids, and some component
wear by-products contain and/or
emit these chemicals.
See Battery - North America 0 383
and Jump Starting - North America
0 435 .
California Perchlorate
Materials Requirements Certain types of automotive
applications, such as airbag
initiators, safety belt pretensioners,
and lithium batteries contained in
Remote Keyless Entry transmitters,
may contain perchlorate materials.
Special handling may be necessary. For additional information, see
www.dtsc.ca.gov/hazardouswaste/
perchlorate.
Accessories and
Modifications Adding non-dealer accessories or
making modifications to the vehicle
can affect vehicle performance and
safety, including such things as
airbags, braking, stability, ride and
handling, emissions systems,
aerodynamics, durability, and
electronic systems like antilock
brakes, traction control, and stability
control. These accessories or
modifications could even cause
malfunction or damage not covered
by the vehicle warranty.
Damage to suspension components
caused by modifying vehicle height
outside of factory settings will not be
covered by the vehicle warranty.
Damage to vehicle components
resulting from modifications or the
installation or use of non-GM
certified parts, including control
module or software modifications, is
not covered under the terms of the vehicle warranty and may affect
remaining warranty coverage for
affected parts.
GM Accessories are designed to
complement and function with other
systems on the vehicle. See your
dealer to accessorize the vehicle
using genuine GM Accessories
installed by a dealer technician.
Also, see Adding Equipment to the
Airbag-Equipped Vehicle 0 86 .

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-9955992) - 2017 - crc - 4/18/17
360 Vehicle Care 1. Positive (+) Terminal. See
Jump Starting - North America
0 435 .
2. Battery - North America 0 383 .
3. Coolant Surge Tank and
Pressure Cap. See Cooling
System 0 372 .
4. Engine Air Cleaner/Filter 0 371 .
5. Automatic Transmission
Dipstick (If Equipped). See
“ How to Check Automatic
Transmission Fluid ” under
Automatic Transmission Fluid
(6 Speed Transmission) 0 368
or Automatic Transmission
Fluid (8 Speed Transmission)
0 371 .
6. Remote Negative ( – ) Location.
See Jump Starting - North
America 0 435 .
7. Engine Cooling Fans (Out of
View). See Cooling System
0 372 .
8. Engine Oil Fill Cap. See “ When
to Add Engine Oil ” under
Engine Oil 0 364 . 9. Engine Oil Dipstick. See
“ Checking Engine Oil ” under
Engine Oil 0 364 .
10. Brake Fluid Reservoir. See
Brake Fluid 0 381 .
11. Windshield Washer Fluid
Reservoir. See “ Adding Washer
Fluid ” under Washer Fluid
0 380 .
12. Engine Compartment Fuse
Block 0 393 .