2020 GMC SIERRA AC low pressure

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
156 Instruments and Controls
Vehicle Messages
Messages displayed on the Driver
Information Center (DIC) indicate
the status of the vehicle or some
action that may be needed to
correct a condition. Multiple
messages may appear one after
another.
The messages that do not require
immediate action can be
acknowledged and cleared by
pressing the thumbwheel. The
messages that require immediate
action cannot be cleared until that
action is performed.
All messages should be taken
seriously; clearing the message
does not correct the problem.
If a SERVICE message appears,
see your dealer.
Follow the instructions given in the
messages. The system displays
messages regarding the following
topics:
.Service Messages
. Fluid Levels .
Vehicle Security
. Brakes
. Steering
. Ride Control Systems
. Driver Assistance Systems
. Cruise Control
. Lighting and Bulb Replacement
. Wiper/Washer Systems
. Doors and Windows
. Seat Belts
. Airbag Systems
. Engine and Transmission
. Tire Pressure
. Battery
Engine Power Messages
ENGINE POWER IS REDUCED
This message displays when the
vehicle's propulsion power is
reduced. A reduction in propulsion
power can affect the vehicle's ability
to accelerate. If this message is on,
but there is no observed reduction in performance, proceed to your
destination. The performance may
be reduced the next time the vehicle
is driven. The vehicle may be driven
while this message is on, but
maximum acceleration and speed
may be reduced. Anytime this
message stays on, or displays
repeatedly, the vehicle should be
taken to your dealer for service as
soon as possible.
Under certain operating conditions,
propulsion will be disabled. Try
restarting after the vehicle has been
off for 30 seconds.
Vehicle Speed Messages
SPEED LIMITED TO XXX KM/
H (MPH)
This message shows that the
vehicle speed has been limited to
the speed displayed. The limited
speed is a protection for various
propulsion and vehicle systems,
such as lubrication, thermal, brakes,
suspension, Teen Driver if
equipped, or tires.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 191
Defensive drivers avoid most skids
by taking reasonable care suited to
existing conditions, and by not
overdriving those conditions. But
skids are always possible.
If the vehicle starts to slide, follow
these suggestions:
.Ease your foot off the
accelerator pedal and steer the
way you want the vehicle to go.
The vehicle may straighten out.
Be ready for a second skid if it
occurs.
. Slow down and adjust your
driving according to weather
conditions. Stopping distance
can be longer and vehicle
control can be affected when
traction is reduced by water,
snow, ice, gravel, or other
material on the road. Learn to
recognize warning clues —such
as enough water, ice, or packed
snow on the road to make a
mirrored surface —and slow
down when you have any doubt. .
Try to avoid sudden steering,
acceleration, or braking,
including reducing vehicle speed
by shifting to a lower gear. Any
sudden changes could cause
the tires to slide.
Remember: Antilock brakes help
avoid only the braking skid.
Off-Road Driving
Four-wheel-drive vehicles can be
used for off-road driving. Vehicles
without four-wheel drive and
vehicles not equipped with All
Terrain (AT) or On-Off Road (OOR)
tires must not be driven off-road
except on a level, solid surface. For
contact information about the
original equipment tires, see the
warranty manual.
One of the best ways for successful
off-road driving is to control the
speed.
{Warning
When driving off-road, bouncing
and quick changes in direction
can easily throw you out of
position. This could cause you to
lose control and crash. You and
your passengers should always
wear seat belts.
Before Driving Off-Road
. Have all necessary maintenance
and service work completed.
. Fuel the vehicle, fill fluid levels,
and check inflation pressure in
all tires, including the spare,
if equipped.
. Read all the information about
four-wheel-drive vehicles in this
manual.
. Remove any underbody air
deflector, if equipped. Re-attach
the air deflector after off-road
driving.
. Know the local laws that apply to
off-road driving.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 203
Example 3
1. Vehicle Capacity Weight forExample 3 = 453 kg
(1,000 lb)
2. Subtract Occupant Weight @ 91 kg (200 lb) × 5 =
453 kg (1,000 lb)
3. Available Cargo Weight = 0 kg (0 lb)
Refer to the Tire and Loading
Information label for specific
information about the vehicle's
capacity weight and seating
positions. The combined weight of the driver, passengers, and
cargo should never exceed the
vehicle's capacity weight.
Certification/Tire Label
A vehicle-specific Certification/
Tire label is label is attached to
the center pillar (B-pillar). The
label may show the size of the
vehicle's original tires and the
inflation pressures needed to
obtain the gross weight capacity
of the vehicle. This is called
Gross Vehicle Weight
Rating (GVWR). The GVWRincludes the weight of the
vehicle, all occupants, fuel, and
cargo.
The Certification/Tire label also
may show the maximum weights
for the front and rear axles,
called Gross Axle Weight
Rating (GAWR). To determine
the actual loads on the front and
rear axles, weigh the vehicle at
a weigh station. Your dealer can
help with this. Be sure to spread
the load equally on both sides of
the centerline.
The Certification/Tire label also
contains important information
about the Front Axle Reserve
Capacity. See
Adding a Snow
Plow or Similar Equipment
0 323.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
218 Driving and Operating
Leaving the Vehicle with the
Engine Running
{Warning
It 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 moving 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.
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 system is designed to prevent
movement of the shift lever out of
P (Park), unless the brake pedal is
applied and the ignition is on or in
Service Mode.
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 or
low voltage battery, try charging or
jump starting the battery. See Jump
Starting - North America 0419.
To shift out of P (Park): 1. Apply the brake pedal.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 219
2. Release the parking brake if itis applied. See Electric Parking
Brake 0233.
3. Pull the shift lever toward you, then move it to the desired
position, and release.
If the vehicle still cannot be shifted
out of P (Park): 1. Ease the pressure on, or release the shift lever.
2. While holding the brake pedal, push the shift lever all the way
into P (Park).
3. Pull the shift lever toward you, then move it to the desired
position, and release.
If there is still a problem shifting,
have the vehicle serviced soon.Parking over Things
That Burn
{Warning
Things that can burn could touch
hot exhaust parts under the
vehicle and ignite. Do not park
over papers, leaves, dry grass,
or other things that can burn.
Active Fuel Management
If equipped, Active Fuel
Management allows a V8, V6, or L4
gasoline engine to operate on either
all of its cylinders, or a reduced
number of cylinders, depending on
the driving conditions.
When less power is required, such
as cruising at a constant vehicle
speed, the system will enable
reduced cylinder operation, allowing
the vehicle to achieve better fuel
economy. When greater power is
required, such as accelerating from a stop, passing, or merging onto a
freeway, the system will maintain
full-cylinder operation.
Dynamic Fuel Management
If equipped, Dynamic Fuel
Management calculates the number
of cylinders needed to maximize
fuel economy and meet the driving
demands. Dynamic Fuel
Management allows the engine to
operate in multiple possible
configurations ranging from
1-cylinder up to the full 8-cylinder
operation.
Extended Parking
It is best not to park with the vehicle
running. If the vehicle is left running,
be sure it will not move and there is
adequate ventilation.
See
Shifting Into Park 0217 and
Engine Exhaust 0220.
If the vehicle is left parked and
running with the RKE transmitter
outside the vehicle, it will continue
to run for up to half an hour.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
310 Driving and Operating
Warning (Continued)
.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.
Trailer Tires
Special Trailer (ST) tires differ from
vehicle tires. Trailer tires are
designed with stiff sidewalls to help
prevent sway and to support heavy
loads. These features can make it
difficult to determine if the trailer tire
pressures are low only based on a
visual inspection.
Always check all trailer tire
pressures before each trip when the
tires are cool. Low trailer tire
pressure is a leading cause of trailer
tire blow-outs. If the vehicle is equipped with a
trailer tire pressure monitoring
system, see the trailer tire pressure
monitoring system description and
the trailering app.
Trailer tires deteriorate over time.
The trailer tire sidewall will show the
week and year the tire was
manufactured. Many trailer tire
manufacturers recommend
replacing tires more than six
years old.
Overloading is another leading
cause of trailer tire blow-outs. Never
load your trailer with more weight
than the tires are designed to
support. The load rating is located
on the trailer tire sidewall.
Always know the maximum speed
rating for the trailer tires before
driving. This may be significantly
lower than the vehicle tire speed
rating. The speed rating may be on
the trailer tire sidewall. If the speed
rating is not shown, the default
trailer tire speed rating is 105 km/h
(65 mph).
Trailering App
Trailer Light App
If equipped, the Trailer Lights App is
on the Home Page of the
infotainment display.
Touch Start to cycle the trailer lamps
on and off to determine if they are
working. The test follows this
sequence:
1. The running lights turn on first and remain on throughout the
sequence.
2. The brake lights turn on for about two seconds.
3. The left turn signal light flashes three times.
4. The right turn signal light flashes three times.
5. The reverse lights turn on for about two seconds.
6. Steps 2–5 repeat for approximately one minute and
45 seconds, or until the test
deactivates.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 311
Touch Stop to stop the test. The test
will automatically end after
one minute and 45 seconds.
The sequence also deactivates
when any of the following occur:
.The ignition is turned off.
. The transmission is shifted out
of P (Park).
. The brake pedal is pressed.
. The turn signal is activated.
. The hazard warning lights are
activated.
Trailering App
If equipped, the Trailering App is on
the Home Page of the infotainment
display.
If equipped this feature allows
profiles for connected trailers to be
created to view status, to store and
track trailer usage information, and
to set up towing assistance
features.
The Trailering App Preview will
appear when the Trailering App is
opened for the first time from the Home Page. Touch GET STARTED
in the Trailering App to go into
the app.
When a trailer is electrically
connected, there will be an option to
create a profile, use a guest profile,
or cancel. After Cancel is selected a
third time, Don’t Remind Me will
display and touching that will turn off
the trailer detection pop-up. To turn
the Trailer Detection Alert on, select
ON in the Settings tab.
When a trailer is electrically
connected and after a Trailer Profile
has been created, the trailer
detection pop-up will appear with a
list of all of the custom Trailer
Profiles made on the vehicle. To
load an existing Trailer Profile,
select one of the Trailer Profiles
listed, or load the Guest Trailer
Profile by selecting GUEST
TRAILER. Touching Cancel,
Accessory/No trailer, or shifting the
vehicle from P (Park), will select
Accessory/No trailer as the active
Trailer Profile and will dismiss the
pop- up.
Create a Trailer Profile
1. Touch Create Profile on the pop-up or touch + Add Trailer
in the Trailering App.
2. Create a name for the trailer.
3. Select the hitch type. A checklist profile will be
created based on the type
selected.
4. Select the trailer type.
A pop-up will indicate the setup is
complete. Touch DONE to complete
the process or touch TRAILER
FEATURE SETUP to set up the
Tow/Haul Mode reminder, Trailer
Tire Pressure Monitoring System,
if equipped, maintenance reminders,
or towing assistance, if equipped.
Import a Trailer Profile
A trailer profile saved to an OnStar
account can be imported to the
vehicle. 1. Touch Import Profile on the pop-up.
2. Select a trailer profile from the list.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
312 Driving and Operating
3. Touch IMPORT.
A pop-up will indicate the import
was successful. Touch OK to return
to the trailer list and select the trailer
profile. The Tow/Haul Mode
reminder, Brake Gain Setting and
Trailer Tire Pressure sensor
learning, if equipped, do not import.
Trailer Feature Setup
Tow/Haul Mode Reminder
To turn the Tow/Haul Mode
Reminder setting on, touch Yes. To
turn it off, touch No.
Trailer Tire Pressure Setup
If the Trailer Tire Pressure
Monitoring System (TTPMS) is
detected, touch the Tire Pressure
Monitoring icon to set up tire
pressure monitoring.Touch Yes to
set up the sensors or touch No to
return to the previous screen.
A trailer must be electrically
connected to the vehicle before
starting the sensor-to-vehicle learn
process. After selecting Start from the Learn
Sensors screen, use the Tool
Method or the Manual Method
(described below) to learn each tire
sensor, during which the current tire
number will be highlighted.
Each sensor has a minimum of
two minutes to learn, shown by a
timer. After a sensor is learned, a
checkmark appears next to the tire,
the vehicle horn will sound, the
vehicle’s brake lamps will flash, and
all working trailer lamps will flash.
It then moves to the next sensor.
To cancel the process touch Stop.
The recommended tire pressure
must be entered for the trailer tires.
This allows the vehicle to alert when
the tire pressure is high or low.
TTPMS must learn the location of
the installed tire sensors to show
correct air pressure and
temperature for each tire. To set up,
use one of the following options or
see a tire or trailer dealer for
service. The learning process must
be repeated when the trailer tires
are rotated or replaced. See
“Editinga Trailer Profile”
later in this section
for tire pressure sensor relearn
information.
Tool Method: A TTPMS activation
tool can be purchased separately to
learn the sensor locations.
Manual Method: Without the tool,
the air pressure can be increased or
decreased in each tire for
10 seconds. Do not exceed the
maximum inflation pressure found
on the tire sidewalls. Make sure to
re-adjust tire pressure to the
recommended level when the
process is complete.
Sensor Learning Steps
To complete the sensor-to-vehicle
learn process:
1. Touch Start on the Learn Sensors screen. The horn
chirps twice and the Learning
Active screen appears on the
infotainment display.
2. Start with the driver side front trailer tire.