2023 CADILLAC CT4 warning light

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
398 Vehicle Care
Brake Fluid
The brake/clutch master
cylinder reservoir is filled with
GM approved DOT 4 brake
fluid as indicated on the
reservoir cap. See Engine
Compartment Overview0373
for the location of the
reservoir.
Checking Brake Fluid
Place the vehicle in P (Park) or
Neutral with the parking brake
applied if equipped with a
manual transmission. On a
level surface, the brake fluid
level should be between the
minimum and maximum marks
on the brake fluid reservoir. There are only two reasons
why the brake fluid level in the
reservoir may go down:
.Normal brake lining wear.
When new linings are
installed, the fluid level goes
back up.
.A fluid leak in the brake/
clutch hydraulic system.
Have the brake/clutch
hydraulic system fixed. With
a leak, the brakes will not
work well.
Always clean the brake fluid
reservoir cap and the area
around the cap before
removing it.
Do not top off the brake/
clutch fluid. Adding fluid does
not correct a leak. If fluid is
added when the linings are
worn, there will be too much
fluid when new brake linings
are installed. Add or remove
fluid, as necessary, only when
work is done on the brake/
clutch hydraulic system.
{Warning
If too much brake fluid is
added, it can spill on the
engine and burn, if the
engine is hot enough. You or
others could be burned, and
the vehicle could be
damaged. Add brake fluid
only when work is done on
the brake/clutch hydraulic
system.
When the brake/clutch fluid
falls to a low level, the brake
warning light comes on. See
Brake System Warning Light
0 120.
Brake fluid absorbs water over
time which degrades the
effectiveness of the brake
fluid. Replace brake fluid at the
specified intervals to prevent
increased stopping distance.
See Maintenance Schedule
0 469.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
Vehicle Care 403
Liftgate
Headlamp Aiming
Front Headlamp
Aiming
Headlamp aim has been preset
and should need no further
adjustment.
If the vehicle is damaged in a
crash, the headlamp aim may
be affected. If adjustment to
the headlamps is necessary,
see your dealer.
Bulb Replacement
For the proper type of
replacement bulbs, or any bulb
changing procedure not listed
in this section, contact your
dealer.
Caution
Do not replace incandescent
bulbs with aftermarket LED
replacement bulbs. This can
cause damage to the vehicle
electrical system.
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.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
Vehicle Care 413
Fuses Usage
35 Hands Free ClosureRelease
36 Exterior Lighting Module 2
37 Passenger Memory Seat Module
38 –
39 Right Front/Right Rear Window
40 –
41 –
42 Amplifier
43 Park Assist Module
44 Driver Memory Seat Module
45 OnStar
46 –
47 –
48 –
49 –
50 Driver Seat 51 Left Front/Left Rear Window
52 Passenger Seat
Relays Usage
53 –
54 –
55 Run
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
(Continued)
Warning (Continued) flexing. There could be
a blowout and a serious
crash. See Vehicle Load
Limits 0255.
.Underinflated tires
pose the same danger
as overloaded tires. The
resulting crash 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.
(Continued)

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
426 Vehicle Care
transmit the tire pressure
readings to a receiver located
in the vehicle.
When a low tire pressure
condition is detected, the
TPMS illuminates the low tire
pressure warning light located
on the instrument cluster.
If the warning light comes on,
stop as soon as possible and
inflate the tires to the
recommended pressure
shown on the Tire and
Loading Information label. See
Vehicle Load Limits0255.
A message to check the
pressure in a specific tire
displays in the Driver
Information Center (DIC). The
low tire pressure warning light
and the DIC warning message
come on at each ignition cycle
until the tires are inflated to the correct inflation pressure.
Using the DIC, tire pressure
levels can be viewed. For
additional information and
details about the DIC
operation and displays see
Driver Information Center
(DIC) (Base Level)
0129 or
Driver Information Center
(DIC) (Uplevel) 0132.
The low tire pressure warning
light may come on in cool
weather when the vehicle is
first started, and then turn off
as the vehicle is driven. This
could be an early indicator
that the air pressure is getting
low and needs to be inflated to
the proper pressure.
A Tire and Loading
Information label, attached to
your vehicle, shows the size of
the original equipment tires
and the correct inflation
pressure for the tires when
they are cold. See Vehicle
Load Limits 0255, for an
example of the Tire and Loading Information label and
its location. Also see Tire
Pressure
0422.
The TPMS can warn about a
low tire pressure condition but
it does not replace normal tire
maintenance. See Tire
Inspection 0429, Tire Rotation
0 429, and Tires 0413.Caution
Tire sealant materials are
not all the same.
A non-approved tire sealant
could damage the TPMS
sensors. TPMS sensor
damage caused by using an
incorrect tire sealant is not
covered by the vehicle
warranty. Always use only
the GM approved tire
sealant available through
your dealer or included in
the vehicle.
Factory-installed Tire Inflator
Kits use a GM-approved liquid
tire sealant. Using
non-approved tire sealants

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
Vehicle Care 427
could damage the TPMS
sensors. See Tire Sealant and
Compressor Kit0439 for
information regarding the
inflator kit materials and
instructions.
TPMS Malfunction Light
and Message
The TPMS will not function
properly if one or more of the
TPMS sensors are missing or
inoperable. When the system
detects a malfunction, the low
tire pressure warning light
flashes for about one minute
and then stays on for the
remainder of the ignition cycle.
A DIC warning message also
displays. The malfunction light
and DIC warning message
come on at each ignition cycle
until the problem is corrected.
Some of the conditions that
can cause these to come
on are:
.One of the road tires has
been replaced with the
spare tire. The spare tire
does not have a TPMS sensor. The malfunction light
and DIC message should go
off after the road tire is
replaced and the sensor
matching process is
performed successfully. See
“TPMS Sensor Matching
Process”
later in this section.
.The TPMS sensor matching
process was not done or not
completed successfully after
rotating the tires. The
malfunction light and the DIC
message should go off after
successfully completing the
sensor matching process.
See "TPMS Sensor Matching
Process" later in this section.
.One or more TPMS sensors
are missing or damaged. The
malfunction light and the DIC
message should go off when
the TPMS sensors are
installed and the sensor
matching process is
performed successfully. See
your dealer for service.
.Replacement tires or wheels
do not match the original
equipment tires or wheels. Tires and wheels other than
those recommended could
prevent the TPMS from
functioning properly. See
Buying New Tires
0432.
.Operating electronic devices
or being near facilities using
radio wave frequencies
similar to the TPMS could
cause the TPMS sensors to
malfunction.
If the TPMS is not functioning
properly it cannot detect or
signal a low tire pressure
condition. See your dealer for
service if the TPMS
malfunction light and DIC
message come on and stay on.
Tire Fill Alert (If Equipped)
This feature provides visual
and audible alerts outside the
vehicle to help when inflating
an underinflated tire to the
recommended cold tire
pressure.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
428 Vehicle Care
When the low tire pressure
warning light comes on:1. Park the vehicle in a safe, level place.
2. Set the parking brake firmly.
3. Place the vehicle in P (Park).
4. Add air to the tire that is underinflated. The turn
signal lamp will flash.
When the recommended
pressure is reached, the
horn sounds once and the
turn signal lamp will stop
flashing and briefly turn
solid.
Repeat these steps for all
underinflated tires that have
illuminated the low tire
pressure warning light.
{Warning
Overinflating a tire could
cause the tire to rupture
and you or others could be
injured. Do not exceed the (Continued)
Warning (Continued)
maximum pressure listed on
the tire sidewall. See Tire
Sidewall Labeling 0417 and
Vehicle Load Limits 0255.
If the tire is overinflated by
more than 35 kPa (5 psi), the
horn will sound multiple times
and the turn signal lamp will
continue to flash for several
seconds after filling stops. To
release and correct the
pressure, while the turn signal
lamp is still flashing, briefly
press the center of the valve
stem. When the recommended
pressure is reached, the horn
sounds once.
If the turn signal lamp does
not flash within 15 seconds
after starting to inflate the
tire, the tire fill alert has not
been activated or is not
working. If the hazard warning flashers
are on, the tire fill alert visual
feedback will not work
properly.
The TPMS will not activate the
tire fill alert properly under the
following conditions:
.There is interference from
an external device or
transmitter.
.The air pressure from the
inflation device is not
sufficient to inflate the tire.
.There is a malfunction in
the TPMS.
.There is a malfunction in the
horn or turn signal lamps.
.The identification code of
the TPMS sensor is not
registered to the system.
.The battery of the TPMS
sensor is low.
If the tire fill alert does not
operate due to TPMS
interference, move the vehicle
about 1 m (3 ft) back or
forward and try again. If the

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
Vehicle Care 431
Warning (Continued)
however, use a scraper
or wire brush later to
remove all rust or dirt.
Lightly coat the center of
the wheel hub with wheel
bearing grease after a
wheel change or tire
rotation to prevent
corrosion or rust build-up.
{Warning
Do not apply grease to
the wheel mounting
surface, wheel conical
seats, or the wheel nuts
or bolts. Grease applied
to these areas could
cause a wheel to become
loose or come off,
resulting in a crash.
When It Is Time for
New Tires
Factors, such as maintenance,
temperatures, driving speeds,
vehicle loading, and road
conditions affect the wear
rate of the tires.
Treadwear indicators are one
way to tell when it is time for
new tires. Treadwear
indicators appear when the
tires have only 1.6 mm (1/16 in)
or less of tread remaining. See
Tire Inspection 0429 and
Tire Rotation 0429. The rubber in tires ages over
time. This also applies to the
spare tire, if the vehicle has
one, even if it is never used.
Multiple factors including
temperatures, loading
conditions, and inflation
pressure maintenance affect
how fast aging takes place.
GM recommends that tires,
including the spare if
equipped, be replaced after six
years, regardless of tread
wear. To identify the age of a
tire, use the tire manufacture
date, which is the last four
digits of the DOT Tire
Identification Number (TIN)
molded into one side of the
tire sidewall. The last four
digits of the TIN indicate the
tire manufactured date. The
first two digits represent the
week and the last two digits,
the year. For example, the
third week of the year 2020
would have a 4-digit DOT date
of 0320. Week 01 is the first
full week (Sunday through
Saturday) of each year.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
432 Vehicle Care
Vehicle Storage
Tires age when stored
normally mounted on a parked
vehicle. Park a vehicle that will
be stored for at least a month
in a cool, dry, clean area away
from direct sunlight to slow
aging. This area should be free
of grease, gasoline, or other
substances that can
deteriorate rubber.
Parking for an extended
period can cause flat spots on
the tires that may result in
vibrations while driving. When
storing a vehicle for at least a
month, remove the tires or
raise the vehicle to reduce the
weight from the tires.
Buying New Tires
GM has developed and
matched specific tires for
the vehicle. The original
equipment tires installed
were designed to meet
General Motors Tire
Performance CriteriaSpecification (TPC Spec)
system rating. When
replacement tires are
needed, GM strongly
recommends buying tires
with the same TPC Spec
rating.
GM's exclusive TPC Spec
system considers over a
dozen critical specifications
that impact the overall
performance of the vehicle,
including brake system
performance, ride and
handling, traction control,
and tire pressure
monitoring performance.
GM's TPC Spec number is
molded onto the tire's
sidewall near the tire size.
If the tires have an
all-season tread design, the
TPC Spec number will be
followed by MS for mud
and snow. See Tire
Sidewall Labeling
0417 for
additional information. GM recommends replacing
worn tires in complete sets
of four. Uniform tread
depth on all tires will help
to maintain the
performance of the vehicle.
Braking and handling
performance may be
adversely affected if all the
tires are not replaced at
the same time. If proper
rotation and maintenance
have been done, all four
tires should wear out at
about the same time.
However, if it is necessary
to replace only one axle set
of worn tires, place the
new tires on the rear axle.
See Tire Rotation
0429.{Warning
Tires could explode
during improper service.
Attempting to mount or
dismount a tire could
(Continued)