2021 CHEVROLET SILVERADO 2500HD air condition

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
248 Driving and Operating
{Warning
Do not rely on the Driver Assistance
Systems. These systems do not replace
the need for paying attention and driving
safely. You may not hear or feel alerts or
warnings provided by these systems.
Failure to use proper care when driving
may result in injury, death, or vehicle
damage. SeeDefensive Driving 0208.
Under many conditions, these systems
will not:
.Detect children, pedestrians, bicyclists,
or animals.
.Detect vehicles or objects outside the
area monitored by the system.
.Work at all driving speeds.
.Warn you or provide you with enough
time to avoid a crash.
.Work under poor visibility or bad
weather conditions.
.Work if the detection sensor is not
cleaned or is covered by ice, snow,
mud, or dirt. (Continued)
Warning (Continued)
.Work if the detection sensor is
covered up, such as with a sticker,
magnet, or metal plate.
.Work if the area surrounding the
detection sensor is damaged or not
properly repaired.
Complete attention is always required
while driving, and you should be ready to
take action and apply the brakes and/or
steer the vehicle to avoid crashes.
Audible or Safety Alert Seat
Some driver assistance features alert the
driver of obstacles by beeping. To change
the volume of the warning chime, see
“Comfort and Convenience” underVehicle
Personalization 0126.
If equipped with the Safety Alert Seat, the
driver seat cushion may provide a vibrating
pulse alert instead of beeping. To change
this, see “Collision/Detection Systems” under
Vehicle Personalization 0126.
Cleaning
Depending on vehicle options, keep these
areas of the vehicle clean to ensure the best
driver assistance feature performance. Driver Information Center (DIC) messages may
display when the systems are unavailable or
blocked.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
258 Driving and Operating
{Warning
FCA is a warning system and does not
apply the brakes. When approaching a
slower-moving or stopped vehicle ahead
too rapidly, or when following a vehicle
too closely, FCA may not provide a
warning with enough time to help avoid
a crash. It also may not provide any
warning at all. FCA does not warn of
pedestrians, animals, signs, guardrails,
bridges, construction barrels, or other
objects. Be ready to take action and
apply the brakes. SeeDefensive Driving
0 208.
FCA can be disabled through vehicle
personalization. See “Collision/Detection
Systems” underVehicle Personalization
0 126.
Detecting the Vehicle Ahead
FCA warnings will not occur unless the FCA
system detects a vehicle ahead. When a
vehicle is detected, the vehicle ahead
indicator will display green. Vehicles may
not be detected on curves, highway exit
ramps, or hills, due to poor visibility; or if a
vehicle ahead is partially blocked by
pedestrians or other objects. FCA will not
detect another vehicle ahead until it is
completely in the driving lane.
{Warning
FCA does not provide a warning to help
avoid a crash, unless it detects a vehicle.
FCA may not detect a vehicle ahead if
the FCA sensor is blocked by dirt, snow,
or ice, or if the windshield is damaged.
It may also not detect a vehicle on
winding or hilly roads, or in conditions
that can limit visibility such as fog, rain,
or snow, or if the headlamps or
windshield are not cleaned or in proper
condition. Keep the windshield,
headlamps, and FCA sensors clean and in
good repair. Collision Alert
With Head-Up Display
Without Head-Up Display
When your vehicle approaches another
detected vehicle too rapidly, the red FCA
display will flash on the windshield. Also,
eight rapid high-pitched beeps will sound
from the front, or both sides of the Safety
Alert Seat will pulse five times. When this
Collision Alert occurs, the brake system may
prepare for driver braking to occur more
rapidly which can cause a brief, mild
deceleration. Continue to apply the brake
pedal as needed. Cruise control may be
disengaged when the Collision Alert occurs.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Driving and Operating 263
Warning (Continued)
If LDW only detects lane markings on one
side of the road, it will only warn you
when departing the lane on the side
where it has detected a lane marking.
Always keep your attention on the road
and maintain proper vehicle position
within the lane, or vehicle damage,
injury, or death could occur. Always keep
the windshield, headlamps, and camera
sensors clean and in good repair. Do not
use LDW in bad weather conditions.
How the System Works
LDW utilizes a camera sensor installed on
the windshield ahead of the rearview mirror
to detect lane markings.
To turn LDW on and off, press
@on the
center stack. The control indicator will light
when LDW is on.
When LDW is on,@is green if LDW is
available to warn of a lane departure. If the
vehicle crosses a detected lane marking
without using the turn signal in that
direction,
@changes to amber and flashes.
Additionally, there will be three beeps, on
the right or left, depending on the lane
departure direction. LDW will not alert if the
turn signal is active in the direction of lane
departure or if LDA detects that you are
accelerating, braking or actively steering.
Fuel
Top Tier Fuel
GM recommends the use of TOP TIER
Detergent Gasoline to keep the engine clean,
reduce engine deposits, and maintain
optimal vehicle performance. Look for the
TOP TIER Logo or see www.toptiergas.com
for a list of TOP TIER Detergent Gasoline
marketers and applicable countries.
Recommended Fuel
For diesel engine vehicles, see “Fuel for
Diesel Engines” in the Duramax diesel
supplement.
If the vehicle has a yellow sticker on the
fuel door, E85 or FlexFuel can be used. If the
vehicle does not have a yellow sticker, do
not use gasoline with ethanol levels greater
than 15% by volume. See E85 or FlexFuel
0 264.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
272 Driving and Operating
Pulling the Trailer from the Water
To pull the trailer out of the water:1. Press and hold the brake pedal.
2. Start the engine and shift into gear.
3. Release the parking brake.
4. Let up on the brake pedal.
5. Drive slowly until the tires are clear of the chocks.
6. Stop and have someone pick up and store the chocks.
7. Slowly pull the trailer from the water.
8. Once the vehicle and trailer have been driven from the sloped part of the boat
ramp, the vehicle can be shifted from
four-wheel-drive high. Shift into the drive
mode that is appropriate for the road
conditions.
Caution
If the vehicle tires begin to spin and the
vehicle begins to slide toward the water,
remove your foot from the accelerator
pedal and apply the brake pedal. Seek
help to have the vehicle towed up
the ramp.
Maintenance when Trailer Towing
The vehicle needs service more often when
used to tow trailers. See Maintenance
Schedule 0384. It is especially important to
check the engine oil, axle lubricant, belts,
cooling system, and brake system before
and during each trip.
Check periodically to see that all nuts and
bolts on the trailer hitch are tight.
Engine Cooling When Trailer Towing
The cooling system may temporarily
overheat during severe operating conditions.
See Engine Overheating 0312.
Trailer Towing
If equipped with a diesel engine, see the
Duramax diesel supplement.
Caution
Towing a trailer improperly can damage
the vehicle and result in costly repairs
not covered by the vehicle warranty. To
tow a trailer correctly, follow the
directions in this section and see your
dealer for important information about
towing a trailer with the vehicle. Trailering is different than just driving the
vehicle by itself. Trailering means changes in
handling, acceleration, braking, durability,
and fuel economy. Successful, safe trailering
takes correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips and
safety rules. Many of these are important
for your safety and that of your passengers.
Read this section carefully before pulling a
trailer.
Trailer Weight
{Warning
Never exceed the towing capacity for
your vehicle.
Safe trailering requires monitoring the
weight, speed, altitude, road grades, outside
temperature, and how frequently the vehicle
is used to tow a trailer.
Trailer Weight Ratings
When towing a trailer, the combined weight
of the vehicle, vehicle contents, trailer, and
trailer contents must be below all of the
maximum weight ratings for the vehicle,
including:

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
282 Driving and Operating
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 available power output to the
trailer brakes can be adjusted to a wide
range of trailering situations.
The ITBC system is integrated with the
vehicle’s brake, antilock brake, and
StabiliTrak/Electronic Stability Control (ESC)
systems. In trailering conditions that cause
the vehicle’s antilock brake or StabiliTrak/
ESC systems to activate, power sent to the
trailer's brakes will be automatically
adjusted to minimize trailer wheel lock-up.
This does not imply that the trailer has
StabiliTrak/ESC.
If the vehicle’s brake, antilock brake,
or StabiliTrak/ESC systems are not
functioning properly, the ITBC system may
not function fully or at all. Make sure all of
these systems are fully operational to allow
the ITBC system to function properly.
The ITBC system is powered through the
vehicle's electrical system. Turning the
ignition off will also turn off the ITBC
system. The ITBC system is fully functional
only when the ignition is in on.{Warning
Connecting a trailer that has an air brake
system may result in reduced or
complete loss of trailer braking, including
increased stopping distance or trailer
instability which could result in serious
injury, death, or property damage. Only
use the ITBC system with electric or
electric over hydraulic trailer brake
systems.
Trailer Brake Control Panel
1. Manual Trailer Brake Apply Lever
2. Trailer Symbol
3. Trailer Gain Adjustment Buttons

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Driving and Operating 291
trailer is connected. When a trailer is
connected and the ignition is off, the
Trailering App System will periodically pulse
the lighting circuits of the trailer to verify it
is still connected. The trailer lights may
periodically flash as a result of this trailer
connection detection. These flashes may be
more visible in dark ambient light
environments. The flashing or flickering
lights are a normal condition and the
Trailering App System has built-in
protections to prevent the battery from
draining. When Theft Alert is also enabled
the frequency and pattern of this flashing
will change.
Connection Problem
If any of the trailer connections are lost, a
message about the connection issue will
appear on the Driver Information Center
(DIC). The infotainment display will also
show the connection issue in the Connection
Status view.
If a trailer connection is not detected, the
Trailering App will not display the
Connection Status screen.Connection Trailer Lighting Faults Detected
The Trailering App System monitors for
electrical faults on the trailer lights.
A message about the lighting issue will
appear on the DIC. The infotainment display
will also show the lighting issue in the
Connection Status view. Repair your trailer
lights if needed. A trailer lighting issue is
not covered by your GM warranty.
Diagnose View
Touch Diagnose to see more information
about the connection problem.
This view will display the names of the
trailer connector pins, a graphic of the trailer
connector, and a graphic of the back of the
trailer.
Any connector pin that failed will be amber
color, and the location of the corresponding
connection will be highlighted on the
graphic of the back of the trailer.
The Running Lights connection may not
detect partial outages. Activate the light test
to check all trailer lamps. See
“Light Test”
following. Light Test
Touch Start Light Test to cycle the trailer
lights on and off to determine if they are
working. The test follows this sequence:
1. The running lights turn on first and remain on throughout the sequence.
2. The brake lights turn on for about two seconds.
3. The left turn signal light flashes three times.
4. The right turn signal light flashes three times.
5. The reverse lights turn on for about two seconds.
6. Steps 2–5 repeat for approximately one minute and 45 seconds, or until the
test deactivates.
Touch Stop to stop the test. The test will
automatically end after one minute and
45 seconds.
The sequence also deactivates when any of
the following occur:
.The ignition is turned off.
.The transmission is shifted out of P (Park).
.The brake pedal is pressed.
.The turn signal is activated.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
308 Vehicle Care
The oil life system can also be reset as
follows:1. Display the oil life percentage on the DIC. See Driver Information Center (DIC)
(Base Level) 0119 or
Driver Information Center (DIC) (Midlevel
and Uplevel) 0120.
2. Fully press the accelerator pedal slowly three times within five seconds.
3. If the display changes to 100%, the system is reset.
If the vehicle has a CHANGE ENGINE OIL
SOON message and it comes back on when
the vehicle is started and/or the oil
life percentage is near 0%, the engine oil
life system has not been reset. Repeat the
procedure.
Automatic Transmission Fluid
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the
transmission fluid level. The only reason for
fluid loss is a transmission leak or
overheated transmission. This vehicle is not
equipped with a transmission fluid level
dipstick. There is a special procedure for
checking and changing the transmission fluid in these vehicles. Because this procedure is
difficult, this should be done at the dealer.
Contact the dealer for additional information
or the procedure can be found in the service
manual. See
Publication Ordering
Information 0408.
Caution
Use of the incorrect automatic
transmission fluid may damage the
vehicle, and the damage may not be
covered by the vehicle warranty. Always
use the correct automatic transmission
fluid. See Recommended Fluids and
Lubricants 0393.
Change the fluid and filter at the scheduled
maintenance intervals listed in Maintenance
Schedule 0384. Be sure to use the
transmission fluid listed in Recommended
Fluids and Lubricants 0393.
Engine Air Filter Life System
If equipped, this feature provides the engine
air filter’s remaining life and best timing for
a change. The timing to change an engine
air filter depends on driving and
environmental conditions.
When to Change the Engine Air Filter
When the Driver Information Center (DIC)
displays a message to replace the engine air
filter at the next oil change, follow this
timing.
When the DIC displays a message to replace
the engine air filter soon, replace the engine
air filter at the earliest convenience.
The system must be reset after the engine
air filter is changed.
If the DIC displays a message to check the
engine air filter system, see your dealer.
How to Reset the Engine Air Filter Life
System
To reset:
1. Place the vehicle in P (Park).
2. Display the Air Filter Life on the DIC. See Driver Information Center (DIC) (Base
Level) 0119 or
Driver Information Center (DIC) (Midlevel
and Uplevel) 0120.
3. Press
Ton the steering wheel, or press
the trip odometer reset stem if the
vehicle does not have DIC controls, to
move to the Reset/Disable display area.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Vehicle Care 313
If the decision is made not to lift the hood
when this warning appears, get service help
right away. SeeRoadside Assistance Program
0 404.
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