2023 GMC SIERRA trailer

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Driving and Operating 297
Theft Alert
A theft alert can be set if a trailer is
connected and the alert is enabled. When
the trailer is disconnected and the vehicle is
off, an alarm will sound.
Touch Theft Alert in Settings to view the
Theft Alert settings page. These alerts are
based on the Trailer Profile, so the settings
for each Trailer Profile must be turned on or
off. Touch a profile to view more
information or adjust the setting for that
profile.
This setting will be off by default for each
Trailer Profile, including the Guest Trailer
Profile.
A smartphone will receive a notification that
the trailer related to the selected Trailer
Profile is disconnected from the vehicle,
if the setting is on for the active Trailer
Profile, the vehicle has an OnStar or
connected service plan and the smartphone
number has been added to the account for
this notification.
If the setting is turned off for a given Trailer
Profile, the smartphone will not receive this
security notification even if the Trailer
Profile is active.
Tow/Haul Mode Reminder
This is a reminder to turn on the Tow/Haul
Mode when towing a trailer. SeeTow/Haul
Mode 0234.
Touch Tow/Haul Mode Reminder in Settings
to view the Tow/Haul Mode Reminder
settings page. These alerts are based on the
Trailer Profile, so the settings for each
Trailer Profile must be turned on or off.
Touch a profile to view more information or
to adjust the setting for that profile.
This setting will default to OFF for each
Trailer Profile, including the Guest Trailer
Profile.
If Tow/Haul Mode is off and this setting is
on for a Trailer Profile, each time the vehicle
is turned on a reminder will appear to turn
on Tow/Haul Mode when the Trailer Profile
is active.
If Tow/Haul Mode is on and this setting is
on for a Trailer Profile, the reminder will not
appear when the Trailer Profile is active.
Trailer Length Indicator
Touch Trailer Length Indicator to view the
Trailer Length Indicator settings page. If this
setting is ON a guideline is displayed in the side mirror camera view to indicate the rear
of the attached trailer. If this setting is OFF
the guideline will not be displayed.
This setting will default to OFF if the trailer
length indicator feature is not set up. See
"Towing Assistance" for details on the setup.
Conversions and Add-Ons
Add-On Electrical Equipment
{Warning
The Data Link Connector (DLC) is used for
vehicle service and Emission Inspection/
Maintenance testing. See
Malfunction
Indicator Lamp (Check Engine Light) 0120
. 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.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
314 Vehicle Care
In addition, there are ENGINE OVERHEATED
STOP ENGINE, ENGINE OVERHEATED IDLE
ENGINE, and ENGINE POWER IS REDUCED
messages in the Driver Information
Center (DIC).
If the decision is made not to lift the hood
when this warning appears, get service help
right away. SeeRoadside Assistance Program
0 399.
If the decision is made to lift the hood,
make sure the vehicle is parked on a level
surface.
Check to see if the engine cooling fans are
running. If the engine is overheating, the
fans should be running. If they are not, do
not continue to run the engine and have the
vehicle serviced.
If the engine or transmission detects an
impending hot fluid condition, then the
transmission may force upshifts to limit
temperatures. Downshifts may also be
prevented in this instance. Normal operation
may continue unless the display indicates
there is a hot condition and engine should
be idled.If Steam is Coming from the Engine
Compartment
{Warning
Steam and scalding liquids from a hot
cooling system are under pressure.
Turning the pressure cap, even a little,
can cause them to come out at high
speed and you could be burned. Never
turn the cap when the cooling system,
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
If No Steam is Coming from the Engine
Compartment
The ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message, along with a low coolant
condition, can indicate a serious problem.
If there is an engine overheat warning, but
no steam is seen or heard, the problem may
not be too serious. Sometimes the engine
can get a little too hot when the vehicle:
.Climbs a long hill on a hot day.
.Stops after high-speed driving.
.Idles for long periods in traffic.
.Tows a trailer; see Trailer Towing0272.
If the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message appears with no sign of steam, try
this for a minute or so: 1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest fan
speed. Open the windows as necessary.
3. When it is safe to do so, pull off the road, shift to P (Park) or N (Neutral) and
let the engine idle.
If the temperature overheat gauge is no
longer in the overheat zone or an overheat
warning no longer displays, the vehicle can
be driven. Continue to drive the vehicle
slowly for about 10 minutes. Keep a safe
vehicle distance from the vehicle in front.
If the warning does not come back on,
continue to drive normally and have the
cooling system checked for proper fill and
function.
If the warning continues, pull over, stop, and
park the vehicle right away.
If there is still no sign of steam and the
vehicle is equipped with an engine driven
cooling fan, push down the accelerator until
the engine speed is about twice as fast as

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
Vehicle Care 315
normal idle speed for at least five minutes
while the vehicle is parked. If the warning is
still there, turn off the engine and get
everyone out of the vehicle until it
cools down.
If there is no sign of steam, idle the engine
for five minutes while parked. If the warning
is still displayed, turn off the engine until it
cools down.
Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and
the ENGINE POWER IS REDUCED message
displays, an overheat protection mode which
alternates firing groups of cylinders helps to
prevent engine damage. In this mode, a loss
in power and engine performance will be
noticed. This operating mode allows the
vehicle to be driven to a safe place in an
emergency. Driving extended distances and/
or towing a trailer in the overheat
protection mode should be avoided.
If the engine or transmission detects an
impending hot fluid condition, then the
transmission may force upshifts to limit
temperatures. Downshifts may also be
prevented in this instance. Normal operationmay continue unless the display indicates
there is a hot condition and engine should
be idled.
Caution
After driving in the overheated engine
protection operating mode, the engine oil
will be severely degraded. Any repairs
performed before the engine is cool may
cause engine damage. Allow the engine
to cool before attempting any repair.
Repair the cause of coolant loss, change
the oil, and reset the oil life system. See
Engine Oil
0306.
Engine Fan
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement.
The vehicle has a clutched engine cooling
fan. When the clutch is engaged, the fan
spins faster to provide more air to cool the
engine. In most everyday driving conditions,
the fan is spinning slower and the clutch is
not fully engaged. This improves fuel
economy and reduces fan noise. Under
heavy vehicle loading, trailer towing, and/or
high outside temperatures, the fan speed
increases as the clutch more fully engages, so an increase in fan noise may be heard.
This is normal and should not be mistaken
as the transmission slipping or making extra
shifts. It is merely the cooling system
functioning properly. The fan will slow down
when additional cooling is not required and
the clutch partially disengages.
This fan noise may be heard when starting
the engine. It will go away as the fan clutch
partially disengages.
Power Steering Fluid
The power steering fluid reservoir is in the
engine compartment on the driver side of
the vehicle. See
Engine Compartment
Overview 0305 for reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power
steering fluid unless there is a leak
suspected in the system or an unusual noise

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
Vehicle Care 331
FusesUsage
6 –
7 –
8 Fog lamp
9 –
10 –
11 Police upfitter
12 –
13 Washer front
14 Washer rear 15 –
16 –
17 IECL 1
19 DC/AC inverter
20 IECR 2 (LD) / EBCM2 (HD)
21 –
22 IECL 2
24 EBCM 1 25 –
26 – Fuses
Usage
27 Horn
28 –
29 –
30 –
31 –
32 Rear window defogger
33 Heated mirror
34 Parking lamp left 37 –
38 –
39 –
40 Misc ignition 41 Trailer parking lamp
42 Park lamp right
44 –
45 –
46 Engine control module ignition
47 Transmission control module ignition Fuses
Usage
48 –
49 Transmission control module
50 A/C clutch 51 Transfer case control module
52 Front wiper
53 Center high-mounted stop lamp
54 Trailer reverse lamp 55 Trailer back-up lamp
56 SADS 57 TTPM/SBZA
58 Starter motor (LD & HD DSL)
60 Active fuel management 1
61 VES
62 Integrated chassis control module/CVS
63 Trailer battery

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
332 Vehicle Care
FusesUsage
65 Auxiliary underhood electrical center
66 Cooling fan motor left 67 Active fuel management 2
68 –
69 Starter Pinion (LD) / Starter Motor (HD Gas)
71 Cooling fan
72 Cooling fan right/lower
73 Trailer stop/turn lamp left
74 Trailer Interface Module 1
75 DEFC
76 Electric RNG BDS
78 Engine control module
79 Auxiliary battery
80 Cabin cooling pump 81 Trailer stop/turn lamp right Fuses
Usage
82 Trailer Interface Module 2
83 FTZM
84 Trailer brake 85 ENG
86 Engine control module 87 Injector B even
88 O2 B sensor
89 O2 A sensor
90 Injector A odd 91 Engine control module throttle control
92 Cool fan clutch/ Aeroshutter Relays
Usage
5 Headlamp
18 DC/AC inverter
23 Rear window defogger
35 Parking lamp
36 Run/Crank
43 –
59 A/C clutch
64 Starter Motor (LD & HD DSL)
70 Starter Pinion (LD) / Starter Motor (HD Gas)
77 Powertrain

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
Vehicle Care 347
5. If the vehicle has an uplevel DIC, pressand hold the thumbwheel located in the
center of the DIC controls on the right
side of the steering wheel.
If the vehicle has a base level DIC, press
and hold the trip odometer reset stem
for about five seconds. A message asking
if the process should begin should
appear. Select yes and press the trip
odometer reset stem to confirm the
selection.
The horn sounds twice to signal the
receiver is in relearn mode and the TIRE
LEARNING ACTIVE message displays on
the DIC screen.
6. Start with the driver side front tire.
7. Place the relearn tool against the tire sidewall, near the valve stem. Then press
the button to activate the TPMS sensor.
A horn chirp confirms that the sensor
identification code has been matched to
this tire and wheel position.
8. Proceed to the passenger side front tire, and repeat the procedure in Step 7.
9. Proceed to the passenger side rear tire, and repeat the procedure in Step 7. 10. Proceed to the driver side rear tire, and
repeat the procedure in Step 7. The horn
sounds two times to indicate the sensor
identification code has been matched to
the driver side rear tire, and the TPMS
sensor matching process is no longer
active. The TIRE LEARNING ACTIVE
message on the DIC display screen
goes off.
11. Turn the vehicle off.
12. Set all four tires to the recommended air pressure level as indicated on the Tire
and Loading Information label.
Trailer Tire Pressure Monitoring
Operation
If equipped, the Trailer Tire Pressure
Monitoring System (TTPMS) is designed to
monitor the pressure of the trailer tires and
warn the driver when a low pressure
condition exists. TTPMS sensors for four tires
are provided. The system can accommodate
a trailer with up to six tires if additional
sensors are purchased from the dealer. Also,
the system can be paired with up to five
individual trailers.
Prior to use, the vehicle must learn the
sensors by following the learning process.
SeeTrailering App 0287.
Contact your trailer service center or tire
service center to have the pressure sensors
installed inside the trailer tires. The
technician should insert the sensor stem
through the hole in the trailer wheel. When
the sensor is correctly positioned, the nut on
the sensor stem should be tightened to
8Y (6 lb ft). When mounting the trailer
tire onto the trailer wheel be careful not to
damage the sensor.
The Trailering App can be used to view the
tire pressures after the recommended trailer
tire pressures have been entered. Refer to
the trailer tire placard on the trailer or the
trailer tire sidewall for the recommended
tire pressure.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
348 Vehicle Care
The system is compatible with trailer tires
that have placard pressure values from
103 - 689 kpa (15 - 100 psi). The hole in the
wheel for the tire stem must be 11.43 mm
(0.453 in) or 15.88 mm (0.625 in) in
diameter. Use of the pressure sensors on a
wheel with a different stem hole size could
result in loss of air from the tire.
If a low trailer tire pressure condition is
detected, the TTPMS displays a warning
message on the DIC. If the warning message
is displayed, stop as soon as possible and
inflate the tires to the recommended
pressure shown on the tire placard on the
trailer.
In addition, the TTPMS monitors the
temperature of the trailer tires. If the
system detects a high temperature on one
or more of the trailer tires, a warning
message will be displayed on the DIC. If this
warning message is displayed, stop as soon
as possible, and inspect the overheated
trailer tire. Common causes for high trailer
tire temperature are underinflation,
overloading, or tire damage.TTPMS Malfunction Message
The TTPMS will not function properly if one
or more of the trailer tire sensors are
missing or inoperable. If the system detects
a malfunction, a DIC message indicates that
the system requires service. Some of the
conditions that can cause the service
message to occur are:
.One of the trailer tires has been replaced
with the spare tire which does not have a
learned TTPMS sensor. The DIC message
should turn off after the pressure sensor
is installed in the tire, and the learning
process is performed successfully. See
"TTPMS Sensor Learning Process" under
Trailering App0287.
.The TTPMS sensor learning process was
not done or not completed successfully.
The DIC message should go off after
successfully completing the sensor
learning process. See "TTPMS Sensor
Learning Process" under Trailering App
0 287.
.One or more TTPMS sensors are missing
or damaged. The DIC message should go
off when the TTPMS sensors are installed
and the sensor learning process is performed successfully. See "TTPMS
Sensor Learning Process" under
Trailering
App 0287.
.Operating electronic devices or being near
facilities using radio wave frequencies
similar to the TTPMS could cause
interference to the TTPMS which could
cause loss of signal reception from the
sensor.
.If the system does not receive the signal
from an individual sensor, an error
message may not occur until the vehicle
has been driver for a period of time.
If the TTPMS is not functioning properly, it
cannot detect or signal a low tire condition.
See your dealer for service if the DIC
message comes on and stays on when the
trailer tire pressures have been checked and
determined to be correct.
Tire Inspection
We recommend that the tires, including
the spare tire, if the vehicle has one, be
inspected for signs of wear or damage
at least once a month.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
Vehicle Care 371
If equipped, a tow eye may be located near
the spare tire or emergency jack. Do not use
the tow eye to pull the vehicle from the
snow, mud, sand, or ditch. Tow eye threads
may have right or left-hand threads. Use
caution when installing or removing the
tow eye.
The vehicle must be in N (Neutral) and the
electric parking brake must be released
when loading the vehicle onto a flatbed tow
truck.
.If the 12-volt battery is dead and/or
electric parking brake is not released, the
vehicle will not move. Try to jump start
the vehicle with a known good 12-volt
battery, shift the car into N (Neutral), and
release the electric parking brake. Refer to
Jump Starting - North America0367.
.If unsuccessful, the vehicle will not move.
Tire skates or dollies must be used under
the non-rolling tires to prevent vehicle
damage.
Front Attachment Points
The vehicle is equipped with specific
attachment points to be used to pull the
vehicle onto a flatbed car carrier from a flat
road surface. Do not use these attachment
points to pull the vehicle from snow, mud
or sand.
Recreational Vehicle Towing
Recreational vehicle towing means towing
the vehicle behind another vehicle, such as a
motor home. The two most common types
of recreational vehicle towing are dinghy
and dolly towing. Dinghy towing is towing
the vehicle with all four wheels on the ground. Dolly towing is towing the vehicle
with two wheels on the ground and two
wheels on a dolly.
Here are some important things to consider
before recreational vehicle towing:
.Before towing the vehicle, become
familiar with the local laws that apply to
recreational vehicle towing. These laws
may vary by region.
.The towing capacity of the towing
vehicle. Read the tow vehicle
manufacturer's recommendations.
.How far the vehicle can be towed. Some
vehicles have restrictions on how far and
how long the vehicle can be towed.
.Whether the vehicle has the proper
towing equipment. See your dealer or
trailering professional for additional
advice and equipment recommendations.
.Whether the vehicle is ready to be towed.
Just as preparing the vehicle for a long
trip, make sure the vehicle is prepared to
be towed.
Follow the tow vehicle manufacturer’s
instructions. See your dealer or trailering
professional for additional advice and
equipment recommendations.