2023 GMC SIERRA AUX

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Driving and Operating 267
{Warning
Fuel vapors and fuel fires burn violently
and can cause injury or death.
Follow these guidelines to help avoid
injuries to you and others:
.Read and follow all the instructions on
the fuel pump island.
.Turn off the engine when refueling.
.Keep sparks, flames, and smoking
materials away from fuel.
.Do not leave the fuel pump
unattended.
.Avoid using electronic devices while
refueling.
.Do not re-enter the vehicle while
pumping fuel.
.Keep children away from the fuel
pump and never let children
pump fuel.
.Before touching the fill nozzle, touch a
metallic object to discharge static
electricity from your body.(Continued)
Warning (Continued)
.Fuel can spray out if the fuel cap is
opened too quickly. This spray can
happen if the tank is nearly full, and is
more likely in hot weather. Open the
fuel cap slowly and wait for any hiss
noise to stop, then unscrew the cap all
the way.
Turn the fuel cap counterclockwise to
remove. Fully insert and latch the fill nozzle,
begin fueling. For models with dual fuel
tanks, the fuel gauge shows an average of
both tanks. When refueling, refuel the
primary front tank first, then add fuel to the
auxiliary rear tank.
{Warning
Overfilling the fuel tank by more than
three clicks of a standard fill nozzle may
cause:
.Vehicle performance issues, including
engine stalling and damage to the fuel
system.
.Fuel spills.
.Under certain conditions, fuel fires. Be careful not to spill fuel. Wait five seconds
after you have finished pumping before
removing the fill nozzle. Clean fuel from
painted surfaces as soon as possible. See
Exterior Care
0374. Reinstall the cap by
turning it clockwise until it clicks.
{Warning
If a fire starts while you are refueling, do
not remove the fill nozzle. Shut off the
flow of fuel by shutting off the pump or
by notifying the station attendant. Leave
the area immediately.
Caution
If a new fuel cap is needed, get the right
type of cap from your dealer. The wrong
type of fuel cap may not fit properly,
may turn on the malfunction indicator
lamp, and could damage the fuel system
and emissions system. See Malfunction
Indicator Lamp (Check Engine Light)
0 120.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Driving and Operating 279
to the attaching points on the bumper;
otherwise, safety chains should be attached
to holes on the trailer hitch.
Cross the safety chains under the tongue of
the trailer to help prevent the tongue from
contacting the road if it becomes separated
from the hitch. Always leave enough slack in
the safety chains to allow the combination
to turn. Never allow safety chains to drag
on the ground.
Trailer Brakes
Loaded trailers over 900 kg (2,000 lb) must
be equipped with brake systems and with
brakes for each axle. Trailer braking
equipment conforming to Canadian
Standards Association (CSA) requirement
CAN3-D313, or its equivalent, is
recommended.
State or local regulations may require
trailers to have their own braking system if
the loaded weight of the trailer exceeds
certain minimums that can vary from state
to state. Read and follow the instructions for
the trailer brakes so they are installed,
adjusted, and maintained properly. Never
attempt to tap into your vehicle's hydraulicbrake system. If you do, both the vehicle
antilock brakes and the trailer brakes may
not function, which could result in a crash.
Auxiliary Battery
If equipped, the vehicle's auxiliary battery
can be used to supply electrical power to
additional equipment that may be added,
such as a slide-in camper.
Locate the auxiliary battery connector under
the hood on the driver side of the vehicle,
next to the engine compartment fuse block.
Follow the proper installation instructions
included with any electrical equipment that
is installed.
Caution
To prevent draining the auxiliary battery,
always turn off electrical equipment
when not in use and do not use any
equipment that may exceed the
maximum amperage rating of 30 amps.
Trailer Wiring Harness
Basic Trailer Wiring
If the vehicle is not equipped with a trailer
connector on the rear bumper, a 7-wire
trailering harness is tied to the vehiclesframe. The harness requires the installation
of a trailer connector, which is available
through your dealer.
Use only a round, seven-wire connector with
flat blade terminals meeting SAE J2863
specifications for proper electrical
connectivity.
The seven-wire harness contains the
following trailer circuits:
Stop/Turn
Signal Left Yellow/Blue
Stop/Turn Signal
Right Green/Violet
Tail/Parking Lamps Gray/Brown
Reverse Lamps White/Green
Battery Feed Red/Green
Ground White
Electric Trailer Brake Blue
Heavy-Duty Trailer Wiring Harness Package
If equipped, the trailer wiring harness, with
a seven-pin connector and a four-pin
connector, is mounted on the vehicle's rear
bumper.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
280 Driving and Operating
The trailer connectors contain the following
circuits.
1. Ground
2. Tail Lamps3. Left Turn/Brake
4. Right Turn/Brake
1. Left Turn/Brake
2. Tail Lamps
3. Reverse Lamps
4. Battery Feed
5. Right Turn/Brake
6. Electric Brakes
7. Ground
If equipped, trailering camera connectors are
available in the bumper trailer receptacle in
place of the four pin connector. The inside
trailer auxiliary camera should be installed on the top left hand side (A) and the rear
trailer auxiliary camera (B) should be
installed on the top right hand side.If equipped with the fifth-wheel/gooseneck
trailer package, the harness connector is
mounted on the inside of the pickup bed
behind the rear wheel.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
298 Driving and Operating
Caution
Some electrical equipment can damage
the vehicle or cause components to not
work and would not be covered by the
vehicle warranty. Always check with your
dealer before adding electrical equipment.
Add-on equipment can drain the vehicle's
12-volt battery, even if the vehicle is not
operating.
The vehicle has an airbag system. Before
attempting to add anything electrical to the
vehicle, see Servicing the Airbag-Equipped
Vehicle 073 and
Adding Equipment to the Airbag-Equipped
Vehicle 074.
For information on wiring auxiliary switches,
see www.gmupfitter.com or contact your
dealer.
Adding a Snow Plow or Similar
Equipment
Caution
Do not exceed 72 km/h (45 mph) with a
snow plow mounted to the vehicle. The
vehicle could overheat and be damaged.
Before installing a snow plow on the vehicle,
follow these guidelines:
Caution
If the vehicle does not have the snow
plow prep package, RPO VYU, adding a
plow can damage the vehicle, and the
repairs would not be covered by the
vehicle warranty. Unless the vehicle was
built to carry a snow plow, do not add
one to the vehicle. If the vehicle has RPO
VYU, then the payload the vehicle can
carry will be reduced when a snow plow
is installed. The vehicle can be damaged
if either the front or rear axle ratings or
the Gross Vehicle Weight Rating (GVWR)
are exceeded. The plow the vehicle can carry depends on
many things, such as:
.The options the vehicle came with, and
the weight of those options.
.The weight and number of passengers to
be carried.
.The weight of items added to the vehicle,
like a tool box or truck cap.
.The total weight of any additional cargo
to be carried.
To safely carry a snow plow on the vehicle:
.With a snow plow attached, the engine
coolant temperature gauge may show a
higher temperature than while driving
without one. The snow plow could block
the airflow to the radiator. This could be
more noticeable as vehicle speed
increases. At speeds above 72 km/h
(45 mph), this may cause the engine
coolant to overheat. Move or angle the
snow plow blade to allow increased
airflow to the radiator.
.To increase the airflow, move the snow
plow blade position.
.If driving more than 24 km/h (15 mph),
angle the plow blade position.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/18/22
306 Vehicle Care
1. Remote Negative (–) Location. SeeJump
Starting - North America 0367.
2. Positive (+) Terminal (Under Cover). See Jump Starting - North America 0367.
3. Battery - North America 0319.
4. Engine Air Cleaner/Filter 0310.
5. Engine Oil Dipstick. See “Checking Engine
Oil” under Engine Oil 0306.
6. Engine Cooling Fan (Out of View). See Cooling System 0311.
7. Power Steering Fluid Reservoir. See Power Steering Fluid 0315.
8. Engine Oil Fill Cap. See “When to Add
Engine Oil” underEngine Oil 0306.
9. Auxiliary Battery. Battery - North
America 0319.
10. Brake Fluid Reservoir. See Brake Fluid
0 318.
11. Engine Compartment Fuse Block 0329.
12. Coolant Surge Tank and Pressure Cap. SeeCooling System 0311.
13. Windshield Washer Fluid Reservoir. See “Adding Washer Fluid” underWasher
Fluid 0316.
If the vehicle has a diesel engine, see the
Duramax diesel supplement.Engine Oil
For diesel engine vehicles, see “Engine Oil”
in the Duramax diesel supplement.
To ensure proper engine performance and
long life, careful attention must be paid to
engine oil. Following these simple, but
important steps will help protect your
investment:
.Use engine oil approved to the proper
specification and of the proper viscosity
grade. See “Selecting the Right Engine
Oil” in this section.
.Check the engine oil level regularly and
maintain the proper oil level. See
“Checking Engine Oil” and“When to Add
Engine Oil” in this section.
.Change the engine oil at the appropriate
time. SeeEngine Oil Life System 0308.
.Always dispose of engine oil properly. See
“What to Do with Used Oil” in this
section.
Checking Engine Oil
Check the engine oil level regularly, every
650 km (400 mi), especially prior to a long
trip. The engine oil dipstick handle is a loop.
See Engine Compartment Overview 0305 for
the location.
{Warning
The engine oil dipstick handle may be
hot; it could burn you. Use a towel or
glove to touch the dipstick handle.
If a low oil Driver Information Center (DIC)
message displays, check the oil level.
Follow these guidelines:
.To get an accurate reading, park the
vehicle on level ground. Check the engine
oil level after the engine has been off for
at least two hours. Checking the engine
oil level on steep grades or too soon after
engine shutoff can result in incorrect
readings. Accuracy improves when
checking a cold engine prior to starting.
Remove the dipstick and check the level.
.If unable to wait two hours, the engine
must be off for at least 15 minutes if the
engine is warm, or at least 30 minutes if
the engine is not warm. Pull out the
dipstick, wipe it with a clean paper towel
or cloth, then push it back in all the way.
Remove it again, keeping the tip down,
and check the level.

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
336 Vehicle Care
FusesUsage
F1 Right Doors
F2 Left Doors
F3 Universal Garage Door Opener
F4 –
F5 –
F6 Front Blower
F8 Lumbar Switch
F10 Body Control Module 6/ Body Control Module 7
F11 Seat/Column Lock Module
F12 Body Control Module 3/ Body Control Module 5
F14 Mirrors/Windows Module F17 Steering Wheel Controls
F18 Video Processing Module/ Obstacle Detection
F19 DLIS –Discrete Logic
Ignition Switch
F20 Ventilated Seats F21 NOT R/C Fuses
Usage
F22 Heated Steering Wheel
F23 MISC R/C
F24 Power Take Off/Reflective Light Auxiliary Display/
Instrument Panel Cluster/
Central Gateway Module/
Inside Rear View Mirror/
Overhead Console Module
Ignition
F25 Heating, Ventilation, and Air Conditioning Ignition/
Heating, Ventilation, and
Air Conditioning Auxiliary
F26 USB Ports/Special Equipment Option Retained
Accessory Power
F27 Accessory Power Outlet/ Retained Accessory Power
F28 Accessory Power Outlet/ Battery
F30 Sensing and Diagnostic Module/Parking Brake
F31 Body Control Module 4 Fuses
Usage
F32 Special Equipment Option/ Data Link Connection
F33 Body Control Module 8
F34 Cargo Lamp
F40 CGM –Central Gateway
Module
F41 Infotainment 1
F42 TCP –Telematics
Connectivity Platform
F43 –
F44 –
F45 Body Control Module 2
F46 Heating, Ventilation, and Air Conditioning/Battery 1
F47 Instrument Panel Cluster/ Battery
F48 Transmission Control Module
F49 Body Control Module 1 F50 –
F51 Battery 1
F52 Battery 2

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Index 417
Assistance Systems (cont'd)Parking and Backing . . . . . . . . . . . . . . . . . . . 248
Audio Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Automatic Dimming Mirrors . . . . . . . . . . . . . . . . . . . . . . . 39
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Emergency Braking (AEB) . . . . . . . . . . . . . . 259
Headlamp System . . . . . . . . . . . . . . . . . . . . . . 141
Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Transmission Fluid . . . . . . . . . . . . . . . . . . . . . 309
Transmission Shift Lock ControlFunction Check . . . . . . . . . . . . . . . . . . . . . . . 322
Automatic Transmission Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . 232
Auxiliary
Jack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Roof Mounted Lamp . . . . . . . . . . . . . . . . . . . 144
Avoiding Untrusted Media Devices . . . . . . . .158
Axle Front . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
B
BatteryExterior Lighting Battery Saver . . . . . . . . 147
Load Management . . . . . . . . . . . . . . . . . . . . . 147 Battery (cont'd)
Power Protection . . . . . . . . . . . . . . . . . . . . . . 147
Battery - North America . . . . . . . . . . . . .319, 367
Blade Replacement, Wiper . . . . . . . . . . . . . . . 323
Blind Spot Mirrors . . . . . . . . . . . . . . . . . . . . . . . . 39
Bluetooth Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 176, 177
Brake Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
Pad Life System . . . . . . . . . . . . . . . . . . . . . . . . 317
System Warning Light . . . . . . . . . . . . . . . . . 122
Brake Pad Life System . . . . . . . . . . . . . . . . . . . . 317
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317 Antilock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Brake Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Electric Parking Brake . . . . . . . . . . . . . . . . . . 239
Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Automatic Emergency (AEB) . . . . . . . . . . . 259
Break-In, New Vehicle . . . . . . . . . . . . . . . . . . . . . 221
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . . . 325 Center High-Mounted Stoplamp(CHMSL) and Cargo Lamp . . . . . . . . . . . . 327
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . 325
Headlamp Aiming . . . . . . . . . . . . . . . . . . . . . . 325
Headlamps, Front Turn Signal, Sidemarker, and Parking Lamps . . . . . . 325
License Plate Lamps . . . . . . . . . . . . . . . . . . . 327 Bulb Replacement (cont'd)
Taillamps, Turn Signal, Stoplamps,
and Back-up Lamps . . . . . . . . . . . . . . . . . . 326
Buying New Tires . . . . . . . . . . . . . . . . . . . . . . . . 352
C
Calibration Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
California Perchlorate MaterialsRequirements . . . . . . . . . . . . . . . . . . . . . . . . 302
California Proposition 65 Warning . . . . . 1, 367
Camera
Rear Vision (RVC) . . . . . . . . . . . . . . . . . . . . . . 248
Truck Bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Canadian Vehicle Owners . . . . . . . . . . . . . . . . . . .2
Capacities and Specifications . . . . . . . . . . . . . 393
Carbon Monoxide Engine Exhaust . . . . . . . . . . . . . . . . . . . . . . . . 229
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Winter Driving . . . . . . . . . . . . . . . . . . . . . . . . . 212
Cargo
Tie-Downs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Caution, Danger, and Warning . . . . . . . . . . . . . .2
Center High-Mounted Stoplamp (CHMSL)
and Cargo Lamp . . . . . . . . . . . . . . . . . . . . . 327
Seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51