ECU GMC SIERRA 2023 Owner's Guide

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 91
Rear Center Position
Rear Center Position
2.3. For a top tether in the rear center position: 2.3.1. Remove the driver side head
restraint and center
headrest. See “Head
Restraint or Headrest
Removal and Reinstallation”
later in this section.
2.3.2. Route the top tether (1) through the center loop (2).
2.3.3. Attach the top tether (1) to the driver side top tether
metal anchor (3).
2.3.4. Make sure the child restraint top tether hook is
completely closed and
secured to the top tether
anchor.
3. Tighten the top tether per the child restraint manufacturer's instructions.
When the top tether is properly
tightened, the loop may bend. This is
normal and will not damage the vehicle.
If child restraints are installed in both
outboard positions, both top tethers can
be attached to the center anchor. Top
tethers can be attached for child
restraints in all three rear seating
positions at the same time, following the
routing instructions above. 4. Before placing a child in the child
restraint, make sure it is securely held in
place. To check, grasp the child restraint
at the LATCH path and attempt to move
it side to side and back and forth. There
should be no more than 2.5 cm (1 in) of
movement for proper installation.
Head Restraint or Headrest Removal and
Reinstallation
The second row outboard head restraints or
center headrest can be removed if they
interfere with the proper installation of the
child restraint.
To remove the second row head restraints
or center headrest:

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
92 Seats and Restraints
1. Press both buttons on the head restraintor headrest posts at the same time, and
pull up on the head restraint or
headrest.
2. Store the head restraint or headrest in a secure place.
3. When the child restraint is removed, reinstall the head restraint or headrest
before the seating position is used.
{Warning
With head restraints that are not
installed and adjusted properly, there is a
greater chance that occupants will suffer
a neck/spinal injury in a crash. Do not
drive until the head restraints for all
occupants are installed and adjusted
properly. To reinstall the head restraint or headrest:
1. Insert the head restraint or headrest
posts into the holes in the top of the
seatback. The notches on the posts must
face the driver side of the vehicle.
2. Push the head restraint or headrest down.
3. Try to move the head restraint or headrest to make sure that it is locked in
place.
Replacing LATCH System Parts
After a Crash
{Warning
A crash can damage the LATCH system in
the vehicle. A damaged LATCH system
may not properly secure the child
restraint, resulting in serious injury or
even death in a crash. To help make sure
the LATCH system is working properly
after a crash, see your dealer to have the
system inspected and any necessary
replacements made as soon as possible.
If the vehicle has the LATCH system and it
was being used during a crash, new LATCH
system parts may be needed.
New parts and repairs may be necessary
even if the LATCH system was not being
used at the time of the crash.
Securing Child Restraints (With
the Seat Belt in the Rear Seat)
When securing a child restraint with the
seat belts in a rear seat position, study the
instructions that came with the child
restraint to make sure it is compatible with
this vehicle.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 93
If the child restraint has the LATCH system,
seeLower Anchors and Tethers for Children
(LATCH System) 082 for how and where to
install the child restraint using LATCH. If a
child restraint is secured in the vehicle using
a seat belt and it uses a top tether, see
Lower Anchors and Tethers for Children
(LATCH System) 082 for top tether anchor
locations.
Do not secure a child seat in a position
without a top tether anchor if a national or
local law requires that the top tether be
anchored, or if the instructions that come
with the child restraint say that the top
tether must be anchored.
In Canada, the law requires that
forward-facing child restraints have a top
tether, and that the tether be attached.
If the child restraint or vehicle seat position
does not have the LATCH system, you will
be using the seat belt to secure the child
restraint. Be sure to follow the instructions
that came with the child restraint.
If more than one child restraint needs to be
installed in the rear seat, be sure to read
Where to Put the Restraint 080.Double Cab
1. Remove the head restraint or headrest
prior to installing a forward-facing child
restraint in an outboard rear seating
position. See “Head Restraint or Headrest
Removal and Reinstallation” underLower
Anchors and Tethers for Children (LATCH
System) 082.
2. Put the child restraint on the seat.
3. Pick up the latch plate and run the lap and shoulder portions of the vehicle seat
belt through or around the child
restraint. Ensure the seat belt webbing is
routed as directly as possible and is not
caught on seat handles or plastic trim.
The child restraint instructions will show
you how.
4. Push the latch plate into the buckle untilit clicks.
Position the release button on the
buckle, away from the child restraint, so
that the seat belt could be quickly
unbuckled if necessary.
There must not be direct contact of the
child restraint to the push button.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
94 Seats and Restraints
5. Pull the shoulder belt all the way out ofthe retractor to set the lock. When the
retractor lock is set, the belt can be
tightened but not pulled out of the
retractor.6. To tighten the belt, push down on thechild restraint, pull the shoulder portion
of the belt to tighten the lap portion of
the belt, and feed the shoulder belt back
into the retractor. When installing a
forward-facing child restraint, it may be
helpful to use your knee to push down
on the child restraint as you tighten
the belt.
Try to pull the belt out of the retractor
to make sure the retractor is locked.
If the retractor is not locked, repeat
Steps 5 and 6. 7. For forward-facing child restraints, attach
and tighten the top tether to the top
tether anchor (loop). Refer to the child
restraint instructions, the vehicle LATCH
anchor weight limits, and instructions
listed in Lower Anchors and Tethers for
Children (LATCH System) 082.
8. Before placing a child in the child restraint, make sure it is securely held in
place. To check, grasp the child restraint
at the seat belt path and attempt to
move it side to side and back and forth.
When the child restraint is properly
installed, there should be no more than
2.5 cm (1 in) of movement.
To remove the child restraint, unbuckle the
vehicle seat belt and let it return to the
stowed position. If the top tether is attached
to a top tether anchor, disconnect it.
Reinstall the head restraint or headrest
before the seating position is used. See
“Head Restraint or Headrest Removal and
Reinstallation” underLower Anchors and
Tethers for Children (LATCH System) 082 for
additional information on installing the
headrest properly.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
96 Seats and Restraints
tether. SeeLower Anchors and Tethers
for Children (LATCH System) 082 for
more information on using the top
tether anchors.
7. Before placing a child in the child restraint, make sure it is securely held in
place. To check, grasp the child restraint
at the seat belt path and attempt to
move it side to side and back and forth.
When the child restraint is properly
installed, there should be no more than
2.5 cm (1 in) of movement.
To remove the child restraint, unbuckle the
vehicle seat belt and let it return to the
stowed position. If the top tether is attached
to a top tether anchor, disconnect it.
For outboard rear seating positions, if the
child restraint cannot be installed properly
with the head restraint in place, the head
restraint may be removed. See your dealer
for assistance with removal, and store the
removed head restraint in a secure place.
When the child restraint is removed,
reinstall the head restraint before the
seating position is used. For reinstallation
instructions, see “Head Restraint or Headrest
Removal and Reinstallation” underLower
Anchors and Tethers for Children (LATCH
System) 082.Securing Child Restraints (With
the Seat Belt in the Front
Passenger Seat)
This vehicle has airbags. A rear seat is a
safer place to secure a forward-facing child
restraint. See Where to Put the Restraint
0 80.
In addition, the vehicle has a passenger
sensing system which is designed to turn off
the front outboard passenger frontal airbag
under certain conditions. See Passenger
Sensing System 070 and
Passenger Airbag Status Indicator 0119 for
more information, including important
safety information.
Never put a rear-facing child restraint in the
front. This is because the risk to the
rear-facing child is so great, if the airbag
deploys.
{Warning
A child in a rear-facing child restraint can
be seriously injured or killed if the front
outboard passenger frontal airbag
inflates. This is because the back of the
rear-facing child restraint would be very
(Continued)
Warning (Continued)
close to the inflating airbag. A child in a
forward-facing child restraint can be
seriously injured or killed if the front
outboard passenger frontal airbag inflates
and the passenger seat is in a forward
position.
Even if the passenger sensing system has
turned off the front outboard passenger
frontal airbag, no system is fail-safe. No
one can guarantee that an airbag will not
deploy under some unusual circumstance,
even though it is turned off.
Secure rear-facing child restraints in a
rear seat, even if the airbag is off. If you
secure a forward-facing child restraint in
the front outboard passenger seat,
always move the seat as far back as it
will go. It is better to secure the child
restraint in a rear seat.
SeePassenger Sensing System 070 for
additional information.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 97
If the vehicle does not have a rear seat that
will accommodate a rear-facing child
restraint, a rear-facing child restraint should
not be installed in the vehicle, even if the
airbag is off.
If the child restraint uses a top tether, see
Lower Anchors and Tethers for Children
(LATCH System)082 for top tether anchor
locations.
Do not secure a child seat in a position
without a top tether anchor if a national or
local law requires that the top tether be
anchored, or if the instructions that come
with the child restraint say that the top
tether must be anchored.
In Canada, the law requires that
forward-facing child restraints have a top
tether, and that the tether be attached.
When using the lap-shoulder belt to secure
the child restraint in this position, follow the
instructions that came with the child
restraint and the following instructions:
1. Move the seat as far back as it will go before securing the forward-facing child
restraint. Move the seat upward or the
seatback to an upright position,
if needed, to get a tight installation of the child restraint. There must be finger
clearance between the push button and
the child restraint.
When the passenger sensing system has
turned off the front outboard passenger
frontal airbag, the OFF indicator on the
passenger airbag status indicator should
light and stay lit when you start the
vehicle. See
Passenger Airbag Status
Indicator 0119.
2. Put the child restraint on the seat.
3. Pick up the latch plate and run the lap and shoulder portions of the vehicle seat
belt through or around the restraint.
Ensure the seat belt webbing is routed
as direct as possible and is not caught
on seat handles or plastic trim. The child
restraint instructions will show you how.
Tilt the latch plate to adjust the belt if
needed.
4. Push the latch plate into the buckle untilit clicks.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
98 Seats and Restraints
Position the release button on the
buckle, away from the child restraint, so
that the seat belt could be quickly
unbuckled if necessary.
5. Pull the shoulder belt all the way out ofthe retractor to set the lock. When the
retractor lock is set, the belt can be
tightened but not pulled out of the
retractor.
6. To tighten the belt, push down on thechild restraint, pull the shoulder portion
of the belt to tighten the lap portion of
the belt, and feed the shoulder belt back
into the retractor.
There must be finger clearance between
the push button and the child restraint.
If there is not clearance between the
buckle push button and the child
restraint, move the seat upward and
repeat prior installation steps. Otherwise
secure the child restraint in a rear seat.
When installing a forward-facing child
restraint, it may be helpful to use your
knee to push down on the child restraint
as you tighten the belt. Try to pull the belt out of the retractor
to make sure the retractor is locked.
If the retractor is not locked, repeat
Steps 5 and 6.
7. If the vehicle does not have a rear seat and the child restraint manufacturer
recommends using a top tether anchor,
attach the top tether to the top tether
anchor. Refer to the instructions that
came with the child restraint and to
Lower Anchors and Tethers for Children
(LATCH System) 082.
8. Before placing a child in the child restraint, make sure it is securely held in
place. To check, grasp the child restraint
at the seat belt path and attempt to
move it side to side and back and forth.
When the child restraint is properly
installed, there should be no more than
2.5 cm (1 in) of movement.
If the airbag is off, the OFF indicator in the
passenger airbag status indicator will come
on and stay on when the vehicle is started.
If a child restraint has been installed and
the ON indicator is lit, see “If the On
Indicator Is Lit for a Child Restraint” under
Passenger Sensing System 070.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 99
To remove the child restraint, unbuckle the
vehicle seat belt and let it return to the
stowed position.
Securing Child Restraints (With
the Seat Belt in the Center
Front Seat)
{Warning
A child in a child restraint in the center
front seat can be badly injured or killed
by the frontal airbags if they inflate.
Never secure a child restraint in the
center front seat. It is always better to
secure a child restraint in a rear seat.
Do not use child restraints in the center
front seat position.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
104 Instruments and Controls
Instruments and Controls
Controls
Steering Wheel Adjustment . . . . . . . . . . . 105
Heated Steering Wheel . . . . . . . . . . . . . . . . 105
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Windshield Wiper/Washer . . . . . . . . . . . . 106
Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Power Outlets . . . . . . . . . . . . . . . . . . . . . . . . . 107
Wireless Charging . . . . . . . . . . . . . . . . . . . . . 109
Warning Lights, Gauges, and Indicators
Warning Lights, Gauges, andIndicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Instrument Cluster . . . . . . . . . . . . . . . . . . . . . 111
Speedometer . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Odometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Trip Odometer . . . . . . . . . . . . . . . . . . . . . . . . . 115
Tachometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Fuel Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Engine Oil Pressure Gauge . . . . . . . . . . . . . 116
Engine Coolant Temperature Gauge . . . . 117
Voltmeter Gauge . . . . . . . . . . . . . . . . . . . . . . 118
Seat Belt Reminders . . . . . . . . . . . . . . . . . . . 118
Airbag Readiness Light . . . . . . . . . . . . . . . . . 119
Passenger Airbag Status Indicator . . . . . . 119
Charging System Light . . . . . . . . . . . . . . . . 120
Malfunction Indicator Lamp (Check Engine Light) . . . . . . . . . . . . . . . . . . . . . . . . 120 Brake System Warning Light . . . . . . . . . . . 122
Electric Parking Brake Light . . . . . . . . . . . . 122
Service Electric Parking Brake Light . . . . 122
Antilock Brake System (ABS) Warning
Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Four-Wheel-Drive Light . . . . . . . . . . . . . . . . . 123
Hill Descent Control Light . . . . . . . . . . . . . . 123
Lane Departure Warning (LDW) Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Vehicle Ahead Indicator . . . . . . . . . . . . . . . . 124
Traction Off Light . . . . . . . . . . . . . . . . . . . . . . 124
Traction Control System (TCS)/Electronic Stability Control Light . . . . . . . . . . . . . . . . 124
Electronic Stability Control (ESC) Off Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Engine Coolant Temperature Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Driver Mode Control Light . . . . . . . . . . . . . 125
Tire Pressure Light . . . . . . . . . . . . . . . . . . . . . 126
Engine Oil Pressure Light (Uplevel Cluster) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Low Fuel Warning Light . . . . . . . . . . . . . . . . 127
Security Light . . . . . . . . . . . . . . . . . . . . . . . . . . 127
High-Beam On Light . . . . . . . . . . . . . . . . . . . 127
Front Fog Lamp Light . . . . . . . . . . . . . . . . . . 128
Lamps On Reminder . . . . . . . . . . . . . . . . . . . 128
Cruise Control Light . . . . . . . . . . . . . . . . . . . . 128
Door Ajar Light . . . . . . . . . . . . . . . . . . . . . . . . 128
Information Displays
Driver Information Center (DIC) (Base Level) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Driver Information Center (DIC) (Midlevel and Uplevel) . . . . . . . . . . . . . . . 130
Head-Up Display (HUD) . . . . . . . . . . . . . . . . 132
Vehicle Messages
Vehicle Messages . . . . . . . . . . . . . . . . . . . . . . 135
Engine Power Messages . . . . . . . . . . . . . . . 135
Vehicle Speed Messages . . . . . . . . . . . . . . . 135
Universal Remote System
Universal Remote System . . . . . . . . . . . . . . 135
Universal Remote System
Programming . . . . . . . . . . . . . . . . . . . . . . . . 136
Universal Remote System Operation . . . 137

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Instruments and Controls 127
This light should come on briefly when the
engine starts. When the engine is off and
the vehicle is on, the light should remain
illuminated. If it does not come on under
either condition, contact your dealer.
If the light comes on and stays on when the
engine is running, it may not have adequate
oil pressure. The oil level may be low or
there may be some other oil system
problem. Turn the engine off when it is safe
to do so and contact your dealer.
Low Fuel Warning Light
A Low Fuel Warning Light near the fuel
gauge comes on briefly when the ignition is
turned on as a check to show it is working.It also comes on when the fuel gauge
indicator nears empty. The light turns off
when fuel is added. If it does not, have the
vehicle serviced.
Security Light
The security light should come on briefly as
the engine is started. If it does not come on,
have the vehicle serviced by your dealer.
If the system is working normally, the
indicator light turns off.
If the light stays on and the engine does
not start, there could be a problem with the
theft-deterrent system. See
Immobilizer
Operation 035.
High-Beam On Light
This light comes on when the high-beam
headlamps are in use. See Headlamp High/
Low-Beam Changer 0141.
IntelliBeam Light
This light comes on when the IntelliBeam
system, if equipped, is enabled. See Exterior
Lamp Controls 0139.