2020 GMC SIERRA trailer towing

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 223
D :This position is for normal
driving. It provides the best fuel
economy. If more power is needed
for passing, press the accelerator
pedal down.
. When going less than about 55
km/h (35 mph), push the
accelerator pedal about
halfway down.
. When going about 55 km/h (35
mph) or more, push the
accelerator all the way down.
By doing this, the vehicle shifts
down to the next gear and has
more power.
Use D (Drive) and Tow/Haul Mode
when towing a trailer, carrying a
heavy load, driving on steep hills,
or driving off-road. Shift the
transmission to a lower gear if the
transmission shifts too often.
Downshifting the transmission in
slippery road conditions could result
in skidding. See “Skidding”under
Loss of Control 0190. The vehicle has a shift stabilization
feature that adjusts the transmission
shifting to the current driving
conditions in order to reduce rapid
upshifts and downshifts. This shift
stabilization feature is designed to
determine, before making an
upshift, if the engine is able to
maintain vehicle speed by analyzing
things such as vehicle speed,
throttle position, and vehicle load.
If the shift stabilization feature
determines that a current vehicle
speed cannot be maintained, the
transmission does not upshift and
instead holds the current gear.
In some cases, this could appear to
be a delayed shift, however the
transmission is operating normally.
If the engine or transmission detects
an impending hot fluid condition, the
transmission may upshift to limit
temperatures. Downshifts may also
be prevented. Normal operation
may continue unless the display
indicates there is a hot condition
and engine should be idled. The transmission uses adaptive
shift controls. The adaptive shift
control process continually
compares key shift parameters to
pre-programmed ideal shifts stored
in the transmission’s computer. The
transmission constantly makes
adjustments to improve vehicle
performance according to how the
vehicle is being used, such as with
a heavy load or when the
temperature changes. During this
adaptive shift control process,
shifting might feel different as the
transmission determines the best
settings.
When temperatures are very cold,
the transmission's gear shifting
could be delayed providing more
stable shifts until the engine warms
up. Shifts could be more noticeable
with a cold transmission. This
difference in shifting is normal.
If equipped with the 2.7L L4 engine,
engine speeds may be increased
while driving at highway speeds
while the engine is still warming up.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
224 Driving and Operating
L :This position allows selection of
a range of gears appropriate for
current driving conditions.
If equipped, see “Range Selection
Mode” underManual Mode 0224.
Caution
Spinning the tires or holding the
vehicle in one place on a hill
using only the accelerator pedal
may damage the transmission.
The repair will not be covered by
the vehicle warranty. If the vehicle
is stuck, do not spin the tires.
When stopping on a hill, use the
brakes to hold the vehicle in
place.
Manual Mode
Range Selection Mode
Range Selection Mode helps control
the vehicle's transmission and
vehicle speed while driving downhill
or towing a trailer by letting you
select a desired range of gears.
To use this feature:
1. Move the shift lever to L (Manual Mode).
2. Press the plus/minus buttons on the shift lever to select the
desired range of gears for
current driving conditions.
When the shift lever is moved from
D (Drive) to L (Manual Mode), a
number displays next to the L,
indicating the current transmission
range. This number is the highest gear that
the transmission will command while
operating in L (Manual Mode). All
gears below that number are
available. As driving conditions
change, the transmission can
automatically shift to lower gears.
For example, when L5 is selected,
1 (First) through 5 (Fifth) gears are
automatically shifted by the
transmission, but 6 (Sixth) cannot be
used until the plus/minus button on
the shift lever is used to change to
the range.
When the shift lever is moved from
D (Drive) to L (Manual Mode), a
downshift may occur. The gear that
the transmission is operating in
when the shift lever is moved from
D (Drive) to L (Manual Mode)
determines if a downshift occurs.
See the following charts.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
240 Driving and Operating
Off-Road Mode
Use to improve driving at moderate
speeds, on grass, gravel, dirt,
unpaved roads, or snow-covered
roads that have not been groomed
or plowed.
The accelerator pedal will be more
sensitive to provide finer control of
the torque at the wheels.
StabiliTrak/Electronic Stability
Control (ESC), the Antilock Brake
System (ABS), and the Traction
Control System (TCS) will change
for optimal off-road performance.
Use this mode for public off-road
recreational driving. SeeOff-Road
Driving 0191.
When selected, the Off-Road Mode
indicator light displays in the
instrument cluster. Tow/Haul Mode
This feature assists when pulling a
heavy trailer or a heavy load. See
Tow/Haul Mode
0226.
Tow/Haul Mode 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 0292.
Tow/Haul Mode is most useful when
pulling a heavy trailer or a heavy
load under the following conditions:
. Through rolling terrain
. In stop-and-go traffic
. In busy parking lots where
improved low speed control of
the vehicle is desired
Operating the vehicle in Tow/Haul
Mode when lightly loaded or with no
trailer at all will not cause damage.
However, there is no benefit to
selecting Tow/Haul Mode when the
vehicle is unloaded. Such a
selection when unloaded may result
in unpleasant engine and transmission driving characteristics,
heavy or light steering, and reduced
fuel economy.
When selected, the Tow/Haul Mode
light will display in the instrument
cluster.
If the vehicle is turned off with Tow/
Haul Mode active and then restarted
within four hours or less, Tow/Haul
will remain active. Otherwise the
vehicle will start in Normal Mode.
Terrain Mode
Use for finer control during low
speed, off-road driving. When using
this mode it will mimic the
characteristics of four-wheel-drive
low (4
n) without the torque
capabilities.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
246 Driving and Operating
used, ACC can be turned back on.
Disabling the TCS or StabiliTrak/
ESC system will disengage and
prevent engagement of ACC.
ACC can reduce the need for you to
frequently brake and accelerate,
especially when used on
expressways, freeways, and
interstate highways. When used on
other roads, you may need to take
over the control of braking or
acceleration more often.
{Warning
ACC has limited braking ability
and may not have time to slow
the vehicle down enough to avoid
a collision with another vehicle
you are following. This can occur
when vehicles suddenly slow or
stop ahead, or enter your lane.
Also see“Alerting the Driver” later
in this section. Complete attention
is always required while driving
and you should be ready to take
action and apply the brakes. See
Defensive Driving 0187.
{Warning
ACC will not detect or brake for
children, pedestrians, animals,
or other objects.
Do not use ACC when:
. On winding and hilly roads
or when the camera sensor
is blocked by snow, ice,
or dirt. The system may not
detect a vehicle ahead.
Keep the windshield and
headlamps clean.
. When visibility is poor due
to rain, snow, fog, dirt,
insect residue, or dust;
when other foreign objects
obscure the camera’s view;
or when the vehicle in front
or oncoming traffic causes
additional environmental
obstructions, such as road
spray. ACC performance is
limited under these
conditions.
(Continued)
Warning (Continued)
.On slippery roads where
fast changes in tire traction
can cause excessive
wheel slip
. With extremely heavy cargo
loaded in the cargo area or
rear seat
. When towing a trailer

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
254 Driving and Operating
Other Vehicle Lane Changes
ACC will not detect a vehicle ahead
until it is completely in the lane. The
brakes may need to be manually
applied.
Objects Not Directly in Front of
Your Vehicle
The detection of objects in front of
the vehicle may not be possible if:
.The vehicle or object ahead is
not within your lane.
. The vehicle ahead is shifted, not
centered, or is shifted to one
side of the lane. Driving in Narrow Lanes
Vehicles in adjacent traffic lanes or
roadside objects may be incorrectly
detected when located along the
roadway.
Do Not Use ACC on Hills and
When Towing a Trailer
Do not use ACC when driving on
steep hills or when towing a trailer.
ACC will not detect a vehicle in the
lane while driving on steep hills.
If the brakes are applied, ACC
disengages.
Disengaging ACC
There are three ways to
disengage ACC:
.
Step lightly on the brake pedal. .
Press
*.
. Press
J.
Erasing Speed Memory
The ACC set speed is erased from
memory if
Jis pressed or if the
ignition is turned off.
Weather Conditions Affecting ACC
If the interior temperature is
extremely high, the instrument
cluster may indicate that ACC is
temporarily unavailable. This can be
caused by extreme hot weather
conditions with direct sunlight on the
front camera. ACC will return to
normal operation once the cabin
temperature is lower.
Conditions that are associated with
low visibility, such as fog, rain,
snow, or road spray, may limit ACC
performance. Water droplets from
rain or snow that remain on the
windshield may also limit ACC’s
ability to detect objects.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
264 Driving and Operating
display when a camera
view is active. Each
press of the button will
toggle through the Rear
Trailer View, Trailer Tow
mirror View and Combo
View. To access this
view when in a forward
gear above 12 km/h
(8 mph), touch
CAMERA on the
infotainment display and
touch the Rear Trailer
View/Rear Side View
with Available
Articulation
Functionality/
Picture-in-Picture Side
View icon. Touch X
to exit.
HD Surround Vision with Trailer
Camera Provisions
If equipped, this feature provides
additional views to aid in trailering/
towing. The system shows multiple
views in the infotainment display
using five cameras mounted around
the vehicle and up to two additional
accessory cameras that can be mounted on or in a trailer. The front
camera is in the grille under the
front emblem, the side cameras are
on the bottom of the outside mirrors,
the rear camera is in the tailgate
handle and the bed camera is
mounted on the rear of the cab.
Additionally, up to two accessory
cameras can be mounted to the rear
and/or interior of the trailer. See
your dealer for accessory trailer
cameras. To access, touch
CAMERA on the infotainment
display or shift to R (Reverse). To
return to the previous screen when
not in reverse, touch the Home or
Back buttons on the infotainment
display.
Available camera views:
.
Front/Rear Standard View
. Front/Rear Top-Down View
. Rear Bowl View
. Front/Rear Side View
. Hitch View
. Bed View
. Rear trailer View .
Rear Side view with a available
articulation functionality
. Picture-in-Picture Side View
. Interior Trailer View
. Transparent trailer View
. Surround View
. Guidance Lines
. Hitch Guidance
Surround Vision (360 Degrees)
If equipped, the Surround Vision
system can display various views
surrounding the vehicle in the
infotainment display using four
cameras mounted around the
vehicle. The front camera is in the
grille under the front emblem, the
side cameras are on the bottom of
the outside mirrors, and the rear
camera is in the tailgate handle.
The Surround Vision system can be
accessed by selecting CAMERA in
the infotainment display or when the
vehicle is shifted into R (Reverse).
To return to the previous screen
sooner, when not in R (Reverse),
press the Home or Back button on

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 265
the infotainment system, shift into
P (Park), or, while in D (Drive),
reach a vehicle speed of
approximately 12 km/h (8 mph).
Available camera views:
.Front/Rear Standard View
. Front/Rear Top-Down View
. Rear Bowl View
. Front/Rear Side View
. Hitch View
. Surround View
. Guidance Lines
. Hitch Guidance
Surround Vision
If equipped, this feature provides,
additional views to aid in trailering/
towing. The Front Vision Camera
and Surround Vision cameras are
not supported. The system can
show various views in the
infotainment display using cameras
mounted in and around the vehicle
and trailer. The rear camera is in the
tailgate handle and the cargo bed
camera is mounted on the rear of the cab. Up to two accessory
cameras can be mounted to the rear
and/or interior of the trailer. See
your dealer for these accessory
cameras.
The system can be accessed by
selecting CAMERA in the
infotainment display or when the
vehicle is shifted into R (Reverse).
To return to the previous screen
sooner, when not in R (Reverse),
press the Home or Back button on
the infotainment system or shift into
P (Park).
Available camera views:
.
Rear Standard View
. Hitch View
. Bed View
. Rear Trailer View
. Interior Trailer View
. Guidance Lines
. Hitch Guidance Troubleshooting
The Transparent Trailer calibration
may take longer than expected or
not calibrate if:
.
The vehicle is driven too fast
during calibration. Speed should
be maintained below 50 km/h
(31 mph).
. The vehicle is not driven straight
during calibration. Steering
should be maintained as straight
as possible, excessive steering
during calibration may extend
calibration time.
. The calibration is attempted in
low light. Calibration should be
attempted when there is enough
light.
. The calibration is attempted
during adverse weather
conditions. Calibration during
conditions such as snow or
heavy rain should be avoided.
. The road surface is not ideal for
calibration. Calibration should be
attempted on an alternate road
surface.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 267
{Warning
The Park Assist system does not
detect children, pedestrians,
bicyclists, animals, or objects
located below the bumper or that
are too close or too far from the
vehicle. It is not available at
speeds greater than 8 km/h
(5 mph). To prevent injury, death,
or vehicle damage, even with
Park Assist, always check the
area around the vehicle and
check all mirrors before moving
forward or backing.
The instrument cluster may have a
Park Assist display with bars that
show“distance to object” and objectlocation information for the Front
and Rear Park Assist system. As
the object gets closer, more bars
light up and the bars change color
from yellow to amber to red.
When an object is first detected in
the rear, one beep will be heard
from the rear, or both sides of the
Safety Alert Seat will pulse two
times. When an object is very close
—
<0.4 m (1.5 ft) in the vehicle rear
or <0.3 m (1 ft) in the vehicle front —
a continuous beep will sound from
the rear or front depending on
object location, or both sides of the
Safety Alert Seat will pulse five
times. Beeps for FPA are higher
pitched than for RPA.
Rear Cross Traffic Alert (RCTA)
If equipped, when the vehicle is
shifted into R (Reverse), RCTA
shows a red warning triangle with a
left or right pointing arrow on the
infotainment display to warn of
traffic coming from the left or right.
This system detects objects coming
from up to 20 m (65 ft) from the left
or right side of the vehicle. When an
object is detected, either three beeps sound from the left or right or
three Safety Alert Seat pulses occur
on the left or right side, depending
on the direction of the detected
vehicle.
Use caution while backing up when
towing a trailer, as the RCTA
detection zones that extend out
from the back of the vehicle do not
move further back when a trailer is
towed.
RCTA is disabled when the trailer
connection status is displayed.
RCTA can be turned off. See
“Collision/Detection Systems”
under
Vehicle Personalization 0157.
Turning the Features On or Off
PressXon the center stack to
turn on or off the Front and Rear
Park Assist. The indicator light next