roof GMC SIERRA 2020 User Guide

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 121
depending on how long the
windshield washer had been
activated. SeeWasher Fluid0354
for information on filling the
windshield washer fluid reservoir.
Clear snow and ice from the wiper
blades before using them. If frozen
to the windshield, carefully loosen or
thaw them. Damaged blades should
be replaced. See Wiper Blade
Replacement 0364.
Heavy snow or ice can overload the
wiper motor.
{Warning
In freezing weather, do not use
the washer until the windshield is
warmed. Otherwise the washer
fluid can form ice on the
windshield, blocking your vision.
{Warning
Before driving the vehicle, always
clear snow and ice from the hood,
windshield, roof, and rear of the
vehicle, including all lamps and
windows. Reduced visibility from
snow and ice buildup could lead
to a crash.
Wipe Parking
If the ignition is turned off while the
wipers are on LO, HI, or
3, they
will immediately stop.
If the windshield wiper control is ON
then moved to OFF before the driver
door is opened or within 10 minutes,
the wipers will restart and move to
the base of the windshield.
If the ignition is turned off while the
wipers are performing wipes due to
windshield washing, the wipers
continue to run until they reach the
base of the windshield.
Compass
The vehicle may have a compass
display on the Driver Information
Center (DIC). The compass receives
its heading and other information
from the Global Positioning
System (GPS) antenna, Electronic
Stability Control (ESC), and vehicle
speed information.
The compass system is designed to
operate for a certain number of
miles or degrees of turn before
needing a signal from the GPS
satellites. When the compass
display shows CAL, drive the
vehicle for a short distance in an
open area where it can receive a
GPS signal. The compass system
will automatically determine when a
GPS signal is restored and provide
a heading again.
Clock
The time and date for the clock can
be set using the infotainment
system. See “Time/Date”in
“System” under“Settings” in the
infotainment manual.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
166 Lighting
For vehicles first sold in Canada, off
will only work when the vehicle is in
P (Park).
AUTO :Automatically turns on the
headlamps, parking lamps,
taillamps, instrument panel lights,
roof marker lamps (if equipped),
front/rear sidemarker lamps, and
license plate lamps.
;: Turns on the parking lamps
including all lamps, except the
headlamps and fog lamps,
if equipped.
2: Turns on the headlamps
together with the parking lamps,
taillamps, instrument panel lights,
roof marker lamps (if equipped),
front/rear sidemarker lamps, and
license plate lamps.
For some trim levels and series of
trucks first sold in Canada, the
headlamps may turn on with the
parking lamps."
When the headlamps are turned on
while the vehicle is on, the
headlamps turn off automatically
10 minutes after the ignition is
turned off. When the headlamps are turned on while the vehicle is off,
the headlamps will stay on for
10 minutes before turning off to
prevent the battery from being
drained. Turn the headlamp control
off and then back to the headlamp
on position to make the headlamps
stay on for an additional 10 minutes.
To keep the lamps on for more than
10 minutes, the ignition must be on
or in ACC/ACCESSORY.
K:
If equipped, turns on the task
lighting. See Task Lighting 0171.
IntelliBeam System
If equipped, this system turns the
vehicle's high-beam headlamps on
and off according to surrounding
traffic conditions.
The system turns the high-beam
headlamps on when it is dark
enough and there is no other traffic
present.
This light
bcomes on in the
instrument cluster when the
IntelliBeam system is enabled. Turning On and Enabling
IntelliBeam
To enable the IntelliBeam system,
press the button on the end of the
turn signal lever when the exterior
lamp control is in the AUTO or
2
position. The blue high-beam on
light appears on the instrument
cluster when the high beams are on.
Driving with IntelliBeam
The system only activates the high
beams when driving over 40 km/h
(25 mph).
There is a sensor near the top
center of the windshield that
automatically controls the system.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
192 Driving and Operating
To gain more ground clearance if
needed, it may be necessary to
remove the front fascia lower air
dam, if equipped. However, driving
without the air dam reduces fuel
economy.
Caution
Operating the vehicle for
extended periods without the front
fascia lower air dam installed can
cause improper airflow to the
engine. Reattach the front fascia
air dam after off-road driving.
Loading the Vehicle for
Off-Road Driving
{Warning
.Unsecured cargo on the
load floor can be tossed
about when driving over
rough terrain. You or your
(Continued)
Warning (Continued)
passengers can be struck
by flying objects. Secure the
cargo properly.
. Keep cargo in the cargo
area as far forward and as
low as possible. The
heaviest things should be
on the floor, forward of the
rear axle.
. Heavy loads on the roof
raise the vehicle's center of
gravity, making it more likely
to roll over. You can be
seriously or fatally injured if
the vehicle rolls over. Put
heavy loads inside the
cargo area, not on the roof.
For more information about loading
the vehicle, see Vehicle Load Limits
0 200 and
Tires 0379.
Environmental Concerns
.
Always use established trails,
roads, and areas that have been
set aside for public off-road
recreational driving and obey all
posted regulations.
. Do not damage shrubs, flowers,
trees, or grasses or disturb
wildlife.
. Do not park over things that
burn. See Parking over Things
That Burn 0219.
Driving on Hills
Driving safely on hills requires good
judgment and an understanding of
what the vehicle can and cannot do.
{Warning
Many hills are simply too steep
for any vehicle. Driving up hills
can cause the vehicle to stall.
Driving down hills can cause loss
of control. Driving across hills can
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
216 Driving and Operating
3. Light-Duty only, remove theengine heater connector cover
by gently prying with a flat
blade tool.
4. Plug the heater cord into the connector in the front fascia.
5. Plug the cord into a grounded 110-volt AC outlet that is
protected by a ground fault
detection function.
{Warning
Improper use of the heater cord
or an extension cord can damage
the cord and may result in
overheating and fire.
. Plug the cord into a
three-prong electrical utility
receptacle that is protected
by a ground fault detection
function. An ungrounded
outlet could cause an
electric shock.
. Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension
cord in good operating
condition, or using a
damaged heater or
extension cord, could make
(Continued)
Warning (Continued)
it overheat and cause a fire,
property damage, electric
shock, and injury.
. Do not operate the vehicle
with the heater cord
permanently attached to the
vehicle. Possible heater
cord and thermostat
damage could occur.
. While in use, do not let the
heater cord touch vehicle
parts or sharp edges. Never
close the hood on the
heater cord.
. Before starting the vehicle,
unplug the cord, reattach
the cover to the plug, and
securely fasten the cord.
Keep the cord away from
any moving parts.
6. Before starting the engine, be sure to unplug and store
the cord.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 217
The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Retained Accessory
Power (RAP)
When the ignition is turned from on
to off, the following features (if
equipped) will continue to function
for up to 10 minutes, or until the
driver door is opened. These
features will also work when the
ignition is in RUN or ACC/
ACCESSORY:
.Infotainment System
. Power Windows (during RAP
this functionality will be lost
when any door is opened)
. Sunroof (during RAP this
functionality will be lost when
any door is opened)
. Auxiliary Power Outlet
. Audio System
. OnStar System
Shifting Into Park
{Warning
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. With four-wheel drive,
if the transfer case is in
N (Neutral), the vehicle will be
free to roll, even if the shift lever
is in P (Park). Be sure the transfer
case is in a drive gear. If towing a
trailer, see Driving Characteristics
and Towing Tips 0287.
1. Hold the brake pedal down, then set the parking brake. See
Electric Parking Brake 0233. 2. Move the shift lever into the
P (Park) position by pulling the
shift lever toward you and
moving it up as far as it will go.
3. Be sure the transfer case (if equipped) is in a drive
gear –not in N (Neutral).
4. Turn the ignition off. For Key Access, push the ignition key
in, towards the steering column
and then turn the ignition off.
5. For Key Access, remove the key and take it with you. If you
can leave the vehicle with the
ignition key in your hand, the
vehicle is in P (Park).
For Keyless Access, take the
Remote Keyless Entry (RKE)
transmitter with you.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 255
Lighting Conditions Affecting ACC
The ACC front camera can be
affected by poor lighting conditions,
and ACC may have limited
performance when:
.There are changes in brightness,
such as entering and exiting
tunnels, bridges, and
overpasses.
. Low sun angles cause the
camera to not detect objects,
or it is more difficult to detect
objects in the same traffic lane.
. Lighting is poor in the evening or
early morning
. There are multiple changes in
brightness or shadows along the
vehicle roadway.
. In a tunnel without the
headlamps on, or in a tunnel
when there is a vehicle in front
that does not have its
taillamps on. .
Subjected to strong light from
opposing lane traffic in the front
of the vehicle, such as
high-beam headlamps from
oncoming traffic.
Accessory Installations and
Vehicle Modifications
Do not install or place any object
around the front camera windshield
area that would obstruct the front
camera view.
Do not install objects on top of the
vehicle that overhang and obstruct
the front camera, such as a canoe,
kayak, or other items that can be
transported on the vehicle roof.
Do not modify the hood, headlamps,
or fog lamps, as this may limit the
camera’s ability to detect an object.
Cleaning the Sensing System
The camera sensor on the
windshield behind the rearview
mirror can become blocked by
snow, ice, dirt, mud, or debris. This
area needs to be cleaned for ACC
to operate properly. The vehicle headlamps may need to
be cleaned due to dirt, snow, or ice.
Objects that are not illuminated
correctly may be difficult to detect.
If ACC will not operate, regular
cruise control may be available. See
“Switching Between ACC and
Regular Cruise Control”
previously
in this section. Always consider
driving conditions before using
either cruise control system.
For cleaning instructions, see
“Washing the Vehicle” under
Exterior Care 0429.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
378 Vehicle Care
FusesUsage
F30 Sensing and diagnostic module/
Parking brake
F31 Body control module 4
F32 Special equipment option/Data link
connection
F33 Body control module 8
F34 Cargo lamp
F40 CGM
F41 Infotainment 1
F42 TCP
F43 –
F44 AVM
F45 Body control module 2
F46 Heating, ventilation, and air conditioning/
Battery 1
F47 Instrument panel cluster/Battery
F48 Transmission control module Fuses
Usage
F49 Body control module 1
F50 –
F51 Battery 1
F52 Battery 2
F53 –
F54 Sunroof
F55 Driver power seat
F56 DC DC TRANS 1
F57 DC DC TRANS 2
F58 Infotainment 2
Circuit
Breakers Usage
1 Accessory power outlet 2
2 Accessory power outlet 1/Cigarette
Lighter
3 Accessory power outlet 3
4 Accessory power outlet 4 Relays
Usage
K1 Run/Crank
K2 Retained accessory power/Accessory 1
K4 Retained accessory power/Accessory 2
K5 –

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
444 Service and Maintenance
fittings, lubricate the suspension
and steering components every
other oil change for normal
usage and every oil change for
severe usage.
. Inspect power steering for
proper attachment, connections,
binding, leaks, cracks,
chafing, etc.
. Visually inspect drive shafts for
excessive wear, lubricant leaks
or damage including: tube dents,
cracks, constant velocity joint or
universal joint looseness,
cracked or missing boots, loose
or missing boot clamps, center
bearing excessive looseness,
missing or loose fasteners.
. Check restraint system
components. See Safety System
Check 071.
. 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 0429.
. Check starter switch. See Starter
Switch Check 0363.
. Check automatic transmission
shift lock control function. See
Automatic Transmission Shift
Lock Control Function Check
0363.
. Check ignition transmission lock.
See Ignition Transmission Lock
Check 0363.
. Check parking brake and
automatic transmission park
mechanism. See Park Brake and
P (Park) Mechanism Check
0 364.
. 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 is low, service the gas
strut. See Gas Strut(s) 0365. .
Inspect sunroof track and seal,
if equipped. See Sunroof051.
. Verify spare tire key lock
operation and lubricate as
needed. See Tire Changing
0 407.
. Visually inspect the spare tire to
ensure that it is tightly stowed
under the vehicle. Push, pull,
and try to turn the tire. If the
spare tire moves, tighten as
necessary. See Tire Changing
0 407.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
Index 497
Roadside AssistanceProgram . . . . . . . . . . . . . . . . . . . . . . . 467
Roof Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . 51
Rotation, Tires . . . . . . . . . . . . . . . . . . 396
Routing, Engine Drive Belt . . . . . . 462
Running the Vehicle While Parked . . . . . . . . . . . . . . . . . . . . . . . . 220
S
Safety Defects ReportingCanadian Government . . . . . . . . 473
General Motors . . . . . . . . . . . . . . . 474
U.S. Government . . . . . . . . . . . . . 473
Safety Locks . . . . . . . . . . . . . . . . . . . . . 27
Safety System Check . . . . . . . . . . . . 71
Scheduling Appointments . . . . . . . 468
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . 65 Care . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Extender . . . . . . . . . . . . . . . . . . . . . . . . 71
How to Wear Seat BeltsProperly . . . . . . . . . . . . . . . . . . . . . . . 66
Lap-Shoulder Belt . . . . . . . . . . . . . . 68
Reminders . . . . . . . . . . . . . . . . . . . . 136
Replacing after a Crash . . . . . . . . 72
Use During Pregnancy . . . . . . . . . . 70
Seats Adjustment, Front . . . . . . . . . . . . . . . 55 Seats (cont'd)
Center Seat . . . . . . . . . . . . . . . . . . . . 56
Head Restraints . . . . . . . . . . . . . . . . 54
Heated and Ventilated Front . . . . 61
Heated, Rear . . . . . . . . . . . . . . . . . . . 64
Lumbar Adjustment, Front . . . . . . 57
Memory . . . . . . . . . . . . . . . . . . . . . . . . . 59
Power Adjustment, Front . . . . . . . 56
Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Reclining Seatbacks . . . . . . . . . . . . 57
Underseat Storage . . . . . . . . . . . .114
Securing Child Restraints . . . . . . . . . . .105, 108, 109
Security
Light . . . . . . . . . . . . . . . . . . . . . . . . . . 147
OnStar . . . . . . . . . . . . . . . . . . . . . . . 479
Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . 37
Vehicle Alarm . . . . . . . . . . . . . . . . . . . 37
Service . . . . . . . . . . . . . . . . . . . . . . . . . 184 Accessories andModifications . . . . . . . . . . . . . . . . 329
Climate Control System . . . . . . . 177
Doing Your Own Work . . . . . . . . 330
Maintenance Records . . . . . . . . 457
Maintenance, General Information . . . . . . . . . . . . . . . . . . 440
Parts Identification . . . . . . . . . . . . 458
Scheduling Appointments . . . . . 468 Service Electric Parking
Brake Light . . . . . . . . . . . . . . . . . . . . 141
Services Special Application . . . . . . . . . . . 449
Servicing the Airbag . . . . . . . . . . . . . 83
Shift Lock Control Function Check, Automatic
Transmission . . . . . . . . . . . . . . . . . . 363
Shifting Into Park . . . . . . . . . . . . . . . . . . . . . . 217
Out of Park . . . . . . . . . . . . . . . . . . . 218
Side Blind Zone Alert (SBZA) . . . 274
Signals, Turn and Lane-Change . . . . . . . . . . . . . . . . . 170
Snow Plow . . . . . . . . . . . . . . . . . . . . . 323
Special Application Services . . . . 449
Specifications and Capacities . . . . . . . . . . . . . . . . . . . . . 459
Speedometer . . . . . . . . . . . . . . . . . . . 131
Start Assist, Hill . . . . . . . . . . . . . . . . . 235
Start Vehicle, Remote . . . . . . . . . . . 24
Starter Switch Check . . . . . . . . . . . 363
Starting the Engine . . . . . . . . . . . . . 212
Steering . . . . . . . . . . . . . . . . . . . . . . . . 188 Fluid, Power . . . . . . . . . . . . . . . . . . 354
Heated Wheel . . . . . . . . . . . . . . . . 120
Wheel Adjustment . . . . . . . . . . . . .119
Wheel Controls . . . . . . . . . . . . . . . 120

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
498 Index
Steering Column Lock . . . . . . . . . . . 38
StepsPower Assist . . . . . . . . . . . . . . . . . . . 36
Stop/Start System . . . . . . . . . . . . . . 213
Stoplamps and Back-up Lamps Bulb Replacement . . . . . . . . . . . . 368
Storage
Rear . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Storage Areas Center Console . . . . . . . . . . . . . . . .114
Floor Console . . . . . . . . . . . . . . . . .115
Glove Box . . . . . . . . . . . . . . . . . . . . .113
Underseat . . . . . . . . . . . . . . . . . . . . .114
Storage Compartments . . . . . . . . . 113
Struts Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Stuck Vehicle . . . . . . . . . . . . . . . . . . . 199
Sun Visors . . . . . . . . . . . . . . . . . . . . . . . 51
Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . 3
System Brake Pad Life . . . . . . . . . . . . . . . . 356
Engine Air Filter Life . . . . . . . . . . 343
Forward CollisionAlert (FCA) . . . . . . . . . . . . . . . . . . 268
Infotainment . . . . . . . . . . . . . 176, 476
Noise Control . . . . . . . . . . . . . . . . . 362 Systems
Driver Assistance . . . . . . . . . . . . . 256
T
Tachometer . . . . . . . . . . . . . . . . . . . . . 132
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Taillamps
Bulb Replacement . . . . . . . . . . . . 368
Task Lighting . . . . . . . . . . . . . . . . . . . 171
Text Telephone (TTY) Users . . . . 466
Theft-Deterrent Systems . . . . . . . . . 39 Immobilizer . . . . . . . . . . . . . . . . . . . . . 39
Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 All-Season . . . . . . . . . . . . . . . . . . . . 379
All-Terrain . . . . . . . . . . . . . . . . . . . . 381
Buying New Tires . . . . . . . . . . . . . 399
Chains . . . . . . . . . . . . . . . . . . . . . . . . 404
Changing . . . . . . . . . . . . . . . . . . . . . 407
Designations . . . . . . . . . . . . . . . . . 383
Different Size . . . . . . . . . . . . . . . . . 401
Full-Size Spare . . . . . . . . . . . . . . . 418
If a Tire Goes Flat . . . . . . . . . . . . 405
Inspection . . . . . . . . . . . . . . . . . . . . 396
Low Profile . . . . . . . . . . . . . . . . . . . 380
Pressure . . . . . . . . . . . . . . . . . 387, 389
Pressure Light . . . . . . . . . . . . . . . . 145
Pressure Monitor Operation . . 390 Tires (cont'd)
Pressure Monitor System . . . . . 389
Rotation . . . . . . . . . . . . . . . . . . . . . . 396
Sidewall Labeling . . . . . . . . . . . . . 381
Terminology and Definitions . . 385
Uniform Tire Quality
Grading . . . . . . . . . . . . . . . . . . . . . 401
Wheel Alignment and Tire Balance . . . . . . . . . . . . . . . . . . . . . 403
Wheel Replacement . . . . . . . . . . 403
When It Is Time for New Tires . . . . . . . . . . . . . . . . . . . . . . . . 398
Winter . . . . . . . . . . . . . . . . . . . . . . . . 380
Top Tier Fuel . . . . . . . . . . . . . . . . . . . 280
Tow/Haul Mode . . . . . . . . . . . . . . . . . 226
Tow/Haul Mode Light . . . . . . . . . . . 142
Towing Driving Characteristics . . . . . . . . 287
Equipment . . . . . . . . . . . . . . . . . . . . 296
General Information . . . . . . . . . . 287
Recreational Vehicle . . . . . . . . . . 424
Trailer . . . . . . . . . . . . . . . . . . . . . . . . 292
Trailer Sway Control (TSC) . . . 308
Vehicle . . . . . . . . . . . . . . . . . . . . . . . 424
Traction Limited-Slip Differential . . . . . . . 242
Off Light . . . . . . . . . . . . . . . . . . . . . . 143