2021 CADILLAC CT4 service

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 321
3.5. At the same time, press theaccelerator and the brake
pedal for two seconds, then
release.
3.6. At the end of the cycle, check the coolant level in the surge
tank and add coolant if it is
below the indicated line. Turn
the ignition off, allow the
Electronic Control Module
(ECM) to go to sleep, about
two minutes, and repeat
Steps 3.2 –3.6.
Listen for pump activation and
movement of the control valves while
watching the level of the coolant in
the surge tank. If the tank empties,
turn the ignition off, carefully remove
the pressure cap, refill to the indicated
line, replace the pressure cap, and
repeat steps 3.2 –3.6.
The fill and air removal process will
run for approximately 15 minutes.Caution
If the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the cap
is properly and tightly secured.
2.7L L4 Engine
Automatic Coolant Service Fill
Instructions
The vehicle is equipped with a service
feature that assists with filling and
removing air from the cooling system
after service of components or when
coolant is added after being to low.
To use this feature: 1. With a cold system unscrew the cooling system air bleeder cap.
If coolant can be seen through the
bleeder move to Step 3.
2. Add coolant through the surge tank until it is visible through the air
bleeder.
3. Replace the cooling system air bleeder cap.
4. Add coolant to the indicated line on the surge tank. 5. Replace the pressure cap on the
surge tank.
6. Activate the service feature: 6.1. Connect the vehicle to a battery charger.
6.2. Turn the ignition to Service Mode. See Ignition Positions
0 219.
6.3. Turn off the air conditioning.
6.4. Set the parking brake.
6.5. At the same time, press the accelerator and the brake
pedal for two seconds, then
release.
6.6. At the end of the cycle, check the coolant level in the surge
tank and add coolant if it is
below the indicated line. Turn
the ignition off, carefully
remove the pressure cap, refill
to the indicated line, replace
the pressure cap, and repeat
steps 6.2 –6.6.
Listen for pump activation and
movement of the control valves while
watching the level of the coolant in
the surge tank. If the tank empties,
turn the ignition off, carefully remove

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
322 VEHICLE CARE
the pressure cap, refill to the indicated
line, replace the pressure cap, and
repeat steps 6.2–6.6.
The fill and air removal process will
run for approximately 15 minutes.
Caution
If the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the cap
is properly and tightly secured.
Engine Overheating
The vehicle has an indicator to warn
of the engine overheating.
If the decision is made not to lift the
hood when this warning appears, get
service help right away. See Roadside
Service 0403.
If the decision is made to lift the
hood, make sure the vehicle is parked
on a level surface.
Then check to see if the engine
cooling fan is running. If the engine is
overheating, the fan should be running. If it is not, do not continue
to run the engine. Have the vehicle
serviced.
Caution
Do not run the engine if there is a
leak in the engine cooling system.
This can cause a loss of all coolant
and can damage the system and
vehicle. Have any leaks fixed
right away.
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
If an engine overheat warning is
displayed but no steam can be 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.
If the overheat warning is displayed
with no sign of steam: 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 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

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 323
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 no sign of steam, idle the
engine for three minutes while parked.
If the warning is still displayed, turn
off the engine until it cools down.
Washer Fluid
What to Use
When windshield washer fluid is
needed, be sure to read the
manufacturer's instructions before
use. If operating the vehicle in an area
where the temperature may fall below
freezing, use a fluid that has sufficient
protection against freezing.
Adding Washer Fluid
Open the cap with the washer symbol
on it. Add washer fluid until the tank
is full. SeeEngine Compartment
Overview 0309 for reservoir location.
Caution
.Do not use washer fluid that
contains any type of water
repellent coating. This can cause
the wiper blades to chatter
or skip.
.Do not use engine coolant
(antifreeze) in the windshield
washer. It can damage the
windshield washer system and
paint.
.Do not mix water with
ready-to-use washer fluid. Water
can cause the solution to freeze
and damage the washer fluid
tank and other parts of the
washer system.
.When using concentrated washer
fluid, follow the manufacturer
instructions for adding water.
(Continued)
Caution (Continued)
.Fill the washer fluid tank only
three-quarters full when it is very
cold. This allows for fluid
expansion if freezing occurs,
which could damage the tank if
it is completely full.
Brakes
Disc brake linings have built-in wear
indicators that make a high-pitched
warning sound when the brake linings
are worn and new linings are needed.
The sound can come and go or can be
heard all the time when the vehicle is
moving, except when applying the
brake pedal firmly.
{Warning
The brake wear warning sound
means that soon the brakes will not
work well. That could lead to a
crash. When the brake wear
warning sound is heard, have the
vehicle serviced.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
324 VEHICLE CARE
Caution
Continuing to drive with worn-out
brake linings could result in costly
brake repairs.
Some driving conditions or climates
can cause a brake squeal when the
brakes are first applied, clearing up
following several applications. This
does not mean something is wrong
with the brakes.
Properly torqued wheel nuts are
necessary to help prevent brake
pulsation. When tires are rotated,
inspect brake linings for wear and
evenly tighten wheel nuts in the
proper sequence to torque
specifications. See Capacities and
Specifications 0396.
Brake pads should be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does
not return to normal height, or if
there is a rapid increase in pedal
travel. This could be a sign that brake
service may be required.
Replacing Brake System Parts
Always replace brake system parts
with new, approved replacement parts.
If this is not done, the brakes may not
work properly. The braking
performance can change in many
ways if the wrong brake parts are
installed or if parts are improperly
installed.
Brake Pad Life System (If
Equipped)
When to Change Brake Pads
This vehicle has a system that
estimates the remaining life of the
front and rear brake pads. Brake pad
life is displayed in the Driver
Information Center (DIC), along with
a percentage for each axle. The system
must be reset every time the brake
pads are changed.
When the system has determined that
the brake pads need to be replaced, a
message will display, which may
include mileage remaining.
Brake pads should always be replaced
as complete axle sets.
How to Reset the Brake Pad Life
System
The system will automatically detect
when significantly worn brake pads
and sensors are replaced. When the
ignition is turned on after new pads
and sensors are installed, a message
will display. Follow the prompts to
reset the system.
The brake pad life system can also be
manually reset: 1. Display Brake Pad Life on the DIC. See Driver Information Center (DIC)
(Base Level) 0107 or
Driver Information Center (DIC)
(Uplevel) 0110.
2. Press the thumbwheel. Select front or rear pads as appropriate.
3. Select YES on the confirmation message. Repeat for pads on the
other axle if they were also
replaced.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 327
Warning (Continued)
careful. SeeJump Starting - North
America 0366 for tips on working
around a battery without
getting hurt.
Infrequent Usage: Remove the black,
negative (−) cable from the battery to
keep the battery from running down.
Extended Storage: Remove the black,
negative (−) cable from the battery or
use a battery trickle charger.
All-Wheel Drive
If the vehicle is equipped with
All-Wheel-Drive (AWD), this is an
additional system that needs
lubrication.
Transfer Case
Under normal driving conditions,
transfer case fluid does not require
maintenance unless there is a fluid
leak or unusual noise. If required,
have the transfer case serviced by
your dealer.
Park Brake and P (Park)
Mechanism Check
{Warning
When you are doing this check, the
vehicle could begin to move. You or
others could be injured and
property could be damaged. Make
sure there is room in front of the
vehicle in case it begins to roll. Be
ready to apply the regular brake at
once should the vehicle begin
to move.
Park on a fairly steep hill, with the
vehicle facing downhill. Keeping your
foot on the regular brake, set the
parking brake.
.To check the parking brake's
holding ability: With the engine
running and the transmission in
N (Neutral), slowly remove foot
pressure from the regular brake
pedal. Do this until the vehicle is
held by the parking brake only.
.To check the P (Park) mechanism's
holding ability: With the engine
running, shift to P (Park). Then
release the parking brake followed
by the regular brake.
Contact your dealer if service is
required.
Wiper Blade Replacement
Windshield wiper blades should be
inspected for wear and cracking. See
Maintenance Schedule 0380.
Replacement blades come in different
types and are removed in different
ways. For proper type and length, see
Maintenance Replacement Parts 0392.
Caution
Allowing the wiper arm to touch
the windshield when no wiper blade
is installed could damage the
windshield. Any damage that occurs
would not be covered by the vehicle
warranty. Do not allow the wiper
arm to touch the windshield.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
328 VEHICLE CARE
To replace the windshield wiper blade:1. Pull the windshield wiper assembly away from the windshield.
2. Lift up on the latch in the middleof the wiper blade where the wiper
arm attaches.
3. With the latch open, pull the wiper blade down toward the windshield
far enough to release it from the
J-hooked end of the wiper arm.
4. Remove the wiper blade.
5. Reverse Steps 1–3 for wiper blade replacement.
Windshield Replacement
HUD System
The windshield is part of the HUD
system. If the windshield needs to be
replaced, be sure to get one that is
designed for HUD or the HUD image
may look out of focus.
Driver Assistance Systems
If the windshield needs to be replaced
and the vehicle is equipped with a
front camera sensor for the Driver
Assistance Systems, a GM
replacement windshield is
recommended. The replacement
windshield must be installed
according to GM specifications for
proper alignment. If it is not, these
systems may not work properly, they
may display messages, or they may
not work at all. See your dealer for
proper windshield replacement.
Acoustic Windshield
The vehicle is equipped with an
acoustic windshield. If the windshield
needs to be replaced be sure to get an acoustic windshield so you will
continue to have the benefits an
acoustic windshield can provide.
Gas Strut(s)
This vehicle is equipped with gas
strut(s) to provide assistance in lifting
and holding open the hood/trunk/
liftgate system in full open position.
{Warning
If the gas struts that hold open the
hood, trunk, and/or liftgate fail, you
or others could be seriously injured.
Take the vehicle to your dealer for
service immediately. Visually
inspect the gas struts for signs of
wear, cracks, or other damage
periodically. Check to make sure the
hood/trunk/liftgate is held open
with enough force. If struts are
failing to hold the hood/trunk/
liftgate, do not operate. Have the
vehicle serviced.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
330 VEHICLE CARE
Halogen Bulbs
{Warning
Halogen bulbs have pressurized gas
inside and can burst if you drop or
scratch the bulb. You or others
could be injured. Be sure to read
and follow the instructions on the
bulb package.
High Intensity Discharge
(HID) Lighting
{Warning
The High Intensity Discharge (HID)
lighting system operates at a very
high voltage. If you try to service
any of the system components, you
could be seriously injured. Have
your dealer or a qualified technician
service them.
After an HID headlamp bulb has been
replaced, the beam might be a slightly
different shade than it was originally.
This is normal.
LED Lighting
This vehicle has several LED lamps.
For replacement of any LED lighting
assembly, contact your dealer.
Front Turn Signal Lamps
Uplevel
See your dealer for turn signal
replacement.
Base level
To replace one of these lamps: 1. Open the hood.
2. If your vehicle is equipped with a beauty cover, remove the beauty
cover to get access to the bulb.3. Turn the bulb socketcounterclockwise to remove it from
the headlamp assembly.
4. Unplug the electrical connector from the bulb by releasing the clip
on the connector.
5. Replace the bulb and reverse Steps 1–4 to reinstall.
Electrical System
Electrical System Overload
The vehicle has fuses and circuit
breakers to protect against an
electrical system overload.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 339
Wheels and Tires
Tires
Every new GM vehicle has
high-quality tires made by a
leading tire manufacturer. See the
warranty manual for information
regarding the tire warranty and
where to get service. For
additional information refer to the
tire manufacturer.
{Warning
.Poorly maintained and
improperly used tires are
dangerous.
.Overloading the tires can
cause overheating as a result
of too much flexing. There
could be a blowout and a
serious crash. SeeVehicle
Load Limits 0214.
.Underinflated tires pose the
same danger as overloaded
tires. The resulting crash
(Continued)
Warning (Continued)
could cause serious injury.
Check all tires frequently to
maintain the recommended
pressure. Tire pressure should
be checked when the tires
are cold.
.Overinflated tires are more
likely to be cut, punctured,
or broken by a sudden impact
— such as when hitting a
pothole. Keep tires at the
recommended pressure.
.Worn or old tires can cause a
crash. If the tread is badly
worn, replace them.
.Replace any tires that have
been damaged by impacts
with potholes, curbs, etc.
.Improperly repaired tires can
cause a crash. Only the dealer
or an authorized tire service
(Continued)
Warning (Continued)
center should repair, replace,
dismount, and mount the
tires.
.Do not spin the tires in
excess of 56 km/h (35 mph)
on slippery surfaces such as
snow, mud, ice, etc. Excessive
spinning may cause the tires
to explode.
See Tire Pressure for High-Speed
Operation 0347 for inflation
pressure adjustment for
high-speed driving.
All-Season Tires
This vehicle may come with all-season
tires. These tires are designed to
provide good overall performance on
most road surfaces and weather
conditions. Original equipment tires
designed to GM's specific tire
performance criteria have a TPC
specification code molded onto the
sidewall. Original equipment