2020 GMC SIERRA towing

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 293
must be below all of the maximum
weight ratings for the vehicle,
including:
.GCWR: Gross Combined Weight
Rating
. GVWR: Gross Vehicle Weight
Rating
. Maximum Trailer Weight Rating
. GAWR-RR: Gross Axle Weight
Rating-Rear
. Maximum Trailer Tongue Weight
Rating
See “Weight-Distributing Hitch and
Adjustment” underTowing
Equipment 0296 to determine if
equalizer bars are required to obtain
the maximum trailer weight rating.
See “Trailer Brakes” underTowing
Equipment 0296 to determine if
brakes are required based on your
trailer's weight.
The only way to be sure the weight
is not exceeding any of these
ratings is to weigh the tow vehicle
and trailer combination, fully loaded
for the trip, getting individual
weights for each of these items. A trailering information label on the
B-pillar shows tow rating information
for the vehicle.
{Warning
You and others could be seriously
injured or killed if the trailer is too
heavy or the trailer brakes are
inadequate for the load. The
vehicle may be damaged, and the
repairs would not be covered by
the vehicle warranty.
Only tow a trailer if all the steps in
this section have been followed.
Ask your dealer for advice and
information about towing a trailer.
Gross Combined Weight
Rating (GCWR)
GCWR is the total allowable weight
of the completely loaded vehicle
and trailer including any fuel,
passengers, cargo, equipment, and
accessories. Do not exceed the
GCWR for your vehicle. The GCWR
for the vehicle is on the Trailering
Information Label.
To check that the weight of the
vehicle and trailer are within the
GCWR for the vehicle, follow these
steps:
1. Start with the "curb weight" from the Trailering Information
Label.
2. Add the weight of the trailer loaded with cargo and ready
for the trip.
3. Add the weight of all passengers.
4. Add the weight of all cargo in the vehicle.
5. Add the weight of hitch hardware such as a draw bar,
ball, load equalizer bars,
or sway bars.
6. Add the weight of any accessories or aftermarket
equipment added to the
vehicle.
The resulting weight cannot exceed
the GCWR value on the Trailering
Information Label.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
296 Driving and Operating
half of the maximum allowable
tongue weight for the vehicle or
227 kg (500 lb), whichever is less.
Rear Gross Axle Weight Rating
(GAWR-RR)
The GAWR-RR is the total weight
that can be supported by the rear
axle of the vehicle. Do not exceed
the GAWR-RR for the vehicle, with
the tow vehicle and trailer fully
loaded for the trip including the
weight of the trailer tongue. If using
a weight-distributing hitch, do not
exceed the GAWR-RR before
applying the weight distribution
spring bars.
The GAWR-RR for the vehicle is on
the Trailering Information Label.
Ask your dealer for trailering
information or assistance.
Towing Equipment
Hitches
Conventional Hitch
A conventional hitch is bolted to the
frame or cross member of the tow
vehicle, and is generally rated Class
2, 3, or 4.
Gooseneck Hitch
A gooseneck hitch is designed to be
coupled to a special hitch leveraging
a hitch ball, and is mounted over the
rear axle in the truck bed.
Fifth-Wheel Hitch
A fifth-wheel hitch is mounted over
the rear axle in the truck bed, and
leverages a hinged plate—the
same type of hitch leveraged by
semi trucks. Generally, fifth-wheel
hitches accommodate large trailers
with as many as one, two, or three
axles.
Always use the correct hitch
equipment for your vehicle.
Crosswinds, large trucks going by,
and rough roads can affect the
trailer and the hitch.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 297
Proper hitch equipment for your
vehicle helps maintain control of the
vehicle-trailer combination. Many
trailers can be towed using a
weight-carrying hitch which has a
coupler latched to the hitch ball, or a
tow eye latched to a pintle hook.
Other trailers may require a
weight-distributing hitch that uses
spring bars to distribute the trailer
tongue weight between your vehicle
and trailer axles. Fifth-wheel and
gooseneck hitches may also be
used. See“Maximum Trailer Tongue
Weight ”under Trailer Towing 0292
for weight limits with various hitch
types. Avoid sharp turns when using a
step-bumper hitch to prevent
damage. Make wider turns to
prevent contact between your trailer
and your bumper.
Consider using mechanical sway
controls with any trailer. Ask a
trailering professional about sway
controls or refer to the trailer
manufacturer's recommendations
and instructions.Weight-Distributing Hitch and
Adjustment
A weight-distributing hitch may be
useful with some trailers. Use the
following guidelines to determine if a
weight-distributing hitch should
be used.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
298 Driving and Operating
Vehicle SeriesTrailer WeightWeight-Distributing Hitch
Usage Hitch Distribution
1500 Up to 3 175 kg (7,000 lb) Not Required 50%
1500 Over 3 175 kg (7,000 lb) Required50%
2500/3500 Up to 9 080 kg (20,000 lb) Not Required 25%
1. Front of Vehicle
2. H1/H2 Body to Ground
Distance
Towing with Model 1500 Trucks
1. Position the truck so that the trailer is ready to connect.
Keep the trailer detached.
2. Measure the height of the top of the front wheel opening at
the fender to the ground (H1).
3. Attach the vehicle to the trailer. Do not attach weight
distribution bars at this time.
4. Measure the height of the top of the front wheel opening on
the fender to the ground (H2).
5. Install and adjust the tension in the weight-distributing bars per
the manufacturers’
recommendations so that the
height of the front fender is approximately H2−[(H2−H1)/2]
(halfway between the two
measured ride heights).
6. Visually inspect the trailer and weight-distributing hitch to
ensure that the manufacturers’
recommendations have
been met.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 299
MeasurementHeight Example 1500 (mm)
H1 1 000
H2 1 050
H2−H1 50
(H2−H1)/2 25
H2−[(H2−H1)/2] 1 025
Towing with Model 2500/3500
Trucks 1. Position the truck so that the trailer is ready to connect.
Keep the trailer detached.
2. Measure the height of the top of the front wheel opening at
the fender to the ground (H1).
3. Attach the vehicle to the trailer. Do not attach weight
distribution bars at this time.
4. Measure the height of the top of the front wheel opening on
the fender to the ground (H2).
5. Install and adjust the tension in the weight-distributing bars per
the manufacturers’ recommendations so that the
height of the front fender is
approximately H2−[(H2−H1)/4]
(1/4 the difference between the
two measured ride heights,
below the secondary ride
height {H2}).
6. Visually inspect the trailer and weight-distributing hitch to
ensure that the manufacturers’
recommendations have
been met.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
300 Driving and Operating
MeasurementHeight Example 2500/3500 (mm)
H1 1 040
H2 1 080
H2−H1 40
(H2−H1)/4 10
H2−[(H2−H1)/4] 1 070
Tires
.
Do not tow a trailer while using a
compact spare tire on the
vehicle.
. Tires must be properly inflated to
support loads while towing a
trailer. See Tires0379 for
instructions on proper tire
inflation.
Fifth-Wheel and Gooseneck
Trailering
Fifth-wheel and gooseneck trailers
can be used with many pickup
models. These trailers place a
larger percentage of the weight
(kingpin weight) on the tow vehicle
than conventional trailers. Make sure this weight does not cause the
vehicle to exceed GAWR or GVWR.
Fifth-wheel or gooseneck kingpin
weight should be 15–25% of the
trailer weight up to the maximum
amount specified in the trailering
chart for the vehicle. See
“Trailer
Weight" under Trailer Towing0292.
The hitch should be in the pickup
bed so that its centerline is over or
slightly in front of the rear axle. Take
care that it is not so far forward that
it will contact the back of the cab in
sharp turns. This is especially
important for short box pickups.
Trailer pin box extensions and
sliding fifth-wheel hitch assemblies
may be used. 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.
Make sure the hitch is attached to
the tow vehicle frame rails. Do not
use the pickup box for support.
Safety Chains
Always attach safety chains
between the vehicle and the trailer.
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

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
304 Driving and Operating
Trailer Lamps
Always check that all trailer lamps
are working at the beginning of each
trip, and periodically on longer trips.
If equipped, the Trailering App will
monitor the RH turn/brake lamp
circuit, LH turn/brake lamp circuit,
running lamp circuit, and reverse
lamp circuits on the trailer. DIC
messages and Trailering App alerts
may be displayed if lighting circuit
issues are detected on the trailer.
Pressing START LIGHT TEST in the
Trailering App automatically
activates the trailer lamps. The
Trailering App is not a substitute for
manually inspecting your trailer
lamps. SeeTrailering App 0310.
Turn Signals When Towing a
Trailer
When properly connected, the trailer
turn signals will illuminate to indicate
the vehicle is turning, changing
lanes, or stopping. When towing a
trailer, the arrows on the instrument cluster will illuminate even if the
trailer is not properly connected or
the bulbs are burned out.
Tow/Haul Mode
For instructions on how to enter
Tow/Haul Mode, see
Driver Mode
Control 0238.
Tow/Haul assists when pulling a
heavy trailer or a large or 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 “Trailer Weight ”under Trailer
Towing 0292.
Tow/Haul Mode is most useful when
towing a heavy trailer or carrying a
large or heavy load:
. Through rolling terrain.
. In stop-and-go traffic.
. In busy parking lots.
Operating the vehicle in Tow/Haul
Mode when lightly loaded or not
towing will not cause damage; however, it is not recommended and
may result in unpleasant engine and
transmission driving characteristics,
heavy or light steering efforts, and
reduced fuel economy.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
brake systems. These instructions
apply to both types of electric trailer
brakes.
This symbol is on the Trailer Brake
Control Panel on vehicles with an
ITBC system. The power output to
the trailer brakes is proportional to
the amount of vehicle braking. This

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 307
{Warning
Trailer brakes that are
over-gained or under-gained may
not stop the vehicle and the trailer
as intended and can result in a
crash. Always follow the
instructions to set the Trailer Gain
for the proper trailer stopping
performance.
To adjust Trailer Gain for each
towing condition: 1. Drive the vehicle with the trailer attached on a level road
surface representative of the
towing condition and free of
traffic at about 32–40 km/h
(20–25 mph) and fully apply
the Manual Trailer Brake Apply
Lever.
Adjusting Trailer Gain at
speeds lower than 32–40 km/h
(20–25 mph) may result in an
incorrect gain setting. 2. Adjust the Trailer Gain, using
the Trailer Gain (+) or (−)
adjustment buttons, to just
below the point of trailer wheel
lock-up, indicated by trailer
wheel squeal or tire smoke
when a trailer wheel locks.
Trailer wheel lock-up may not
occur if towing a heavily loaded
trailer. Adjust the Trailer Gain
to the highest allowable setting
for the towing condition.
3. Readjust Trailer Gain anytime vehicle loading, trailer loading,
or road surface conditions
change or if trailer wheel
lock-up is noticed at any time
while towing.
Other ITBC-Related DIC
Messages
TRAILER CONNECTED: This
message will briefly display when a
trailer with electric brakes is first
connected to the vehicle. This
message will automatically turn off
in about 10 seconds. This message
can be acknowledged before it
automatically turns off. CHECK TRAILER WIRING: This
message will display if:
.
The ITBC system first
determines connection to a
trailer with electric brakes and
then the trailer harness becomes
disconnected from the vehicle.
If the disconnect occurs while
the vehicle is stationary, this
message will automatically turn
off in about 30 seconds. This
message will also turn off if it is
acknowledged or if the trailer
harness is reconnected.
If the disconnect occurs while
the vehicle is moving, this
message will continue until the
ignition is turned off. This
message will also turn off if it is
acknowledged or if the trailer
harness is reconnected.
. There is an electrical fault in the
wiring to the trailer brakes. This
message will continue as long
as there is an electrical fault in
the trailer wiring. This message
will also turn off if it is
acknowledged.