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Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
348 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. SeeEngine Compartment
Overview 0326 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 0101.
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 0408.
What to Add
Use only GM approved DOT 4 brake
fluid from a clean, sealed container.
See Recommended Fluids and
Lubricants 0417.{Warning
The wrong or contaminated brake
fluid could result in damage to the
brake system. This could result in
the loss of braking leading to a
possible injury. Always use the
proper GM approved brake fluid.
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Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
VEHICLE CARE 349
Caution
If brake fluid is spilled on the
vehicle's painted surfaces, the paint
finish can be damaged. Immediately
wash off any painted surface.
Battery - North America
The original equipment battery is
maintenance free. Do not remove the
cap and do not add fluid.
Refer to the replacement number
shown on the original battery label
when a new battery is needed.
The vehicle has an Absorbed Glass
Mat (AGM) 12-volt battery.
Installation of a standard 12-volt
battery will result in reduced 12-volt
battery life.
When using a 12-volt battery charger
on the 12-volt AGM battery, some
chargers have an AGM battery setting
on the charger. If available, use the
AGM setting on the charger, to limit
charge voltage to 14.8 volts. Follow
the charger manufacturer's
instructions.Stop/Start System
This vehicle has a Stop/Start system
to shut off the engine to help
conserve fuel. See
Stop/Start System
0 235.
{Warning
WARNING: Battery posts,
terminals and related accessories
can expose you to chemicals
including lead and lead compounds,
which are known to the State of
California to cause cancer and birth
defects or other reproductive harm.
Wash hands after handling. For
more information go to
www.P65Warnings.ca.gov.
See the warning on the back cover.
Vehicle Storage
{Warning
Batteries have acid that can burn
you and gas that can explode. You
can be badly hurt if you are not (Continued)
Warning (Continued)
careful. SeeJump Starting - North
America 0390 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.
Page 351 of 464

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
350 VEHICLE CARE
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.
.Automatic transmission vehicles
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 0408.
Replacement blades come in different
types and are removed in different
ways. For proper type and length, see
Maintenance Replacement Parts 0418.
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.
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.
Page 355 of 464
Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
354 VEHICLE CARE
Replacing a Blown Fuse
1. Turn off the ignition.
2. Locate the fuse puller in the enginecompartment fuse block.
3. Use the fuse puller to remove thefuse from the top or side, as shown
above.
4. If the fuse must be replaced immediately, borrow a replacement
fuse with the same amperage from
the fuse block. Choose a vehicle
feature that is not needed to safely
operate the vehicle. Repeat
Steps 2-3.
5. Insert the replacement fuse into the empty slot of the blown fuse.
At the next opportunity, see your
dealer to replace the blown fuse.
Page 357 of 464
Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
356 VEHICLE CARE
Engine Compartment Fuse
Block
The engine compartment fuse block is
on the driver side of the engine
compartment.
Lift the fuse block cover to access the
fuses.
The vehicle may not be equipped with
all of the fuses and relays shown.
Caution
Spilling liquid on any electrical
component on the vehicle may
damage it. Always keep the covers
on any electrical component.
FusesUsage
1 Long Range Radar Front Sensor
2 Park/Daytime Running Lamps
3 Exterior Lighting Module 4
4 Exterior Lighting Module 7
5 Headlamp Level Fuses
Usage
6 –
7 Electronic Brake Control Module
8 Washer Pump
9 –
10 –
11 –
12 Horn
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VEHICLE CARE 357
FusesUsage
13 Front Wiper
14 Exterior Lighting Module 6
15 Exterior Lighting Module 1
16 Exterior Lighting Module 5
17 Exterior Lighting Module 3
18 Aero Shutter
19 –
20 –
21 Virtual Key System/ Power Sounder
Module
22 Engine Control Module Battery
23 Transmission Control Module
24 Active Engine Mount
25 –
26 Engine Control Module Fuses
Usage
27 Injectors/Ignition 2
28 Charged Air Cooler
29 Transmission Aux Oil Pump/Transmission
Reverse Lock Out
30 Injectors/Ignition 1
31 Emissions 1
32 Emissions 2
33 Starter Solenoid
34 –
35 –
36 Starter Pinion
37 AC Clutch
38 –
39 –
40 –
41 –
42 Water Pump
43 –
44 – Relays
Usage
47 –
48 Front Wiper Speed
49 Front Wiper Control
51 –
52 Engine Control Module
53 Starter Solenoid
54 Starter Pinion
55 –
57 AC Clutch
58 –
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Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
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360 VEHICLE CARE
FusesUsage
21 Driver Monitor System/Performance
Data Recorder
22 –
23 –
24 –
25 USB
26 –
27 –
28 –
29 –
30 –
31 Headlamp Level
32 –
33 Body Ignition/IP Ignition
34 Exhaust Valve Fuses
Usage
35 Transmission Control Module Ignition/
Engine Control
Module Ignition/Shift
Ignition/Brake
Ignition
36 Shift Module
37 Body Control Module 1/Electronic
Park Brake Switch
38 Center Stack Module
39 Steering Wheel Controls
40 Body Control Module 2
41 Body Control Module 3
42 Body Control Module 4 Circuit
Breakers Usage
CB1 Auxiliary Power Outlet 1
CB2 Auxiliary Power Outlet 2
Relays Usage
1 Run After Park/ Accessory
2 Run Crank
3 –
4 –
5 –
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Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-15283641) -
2022 - CRC - 10/12/21
VEHICLE CARE 367
(4) Tire Identification Number
(TIN)
:The letters and numbers
following the DOT code are the
Tire Identification Number (TIN).
The TIN shows the manufacturer
and plant code, tire size, and date
the tire was manufactured. The
TIN is molded onto both sides of
the tire, although only one side
may have the date of
manufacture.
(5) Tire Ply Material
:The type
of cord and number of plies in the
sidewall and under the tread.
(6) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more information,
see Uniform Tire Quality Grading
0 380. (7) Maximum Cold Inf lation
Load Limit
:Maximum load that
can be carried and the maximum
pressure needed to support
that load.
Tire Designations
Tire Size
The example shows a typical
passenger vehicle tire size.
Passenger (P-Metric) Tire
(1) Passenger (P-Metric) Tire:
The United States version of a
metric tire sizing system. The
letter "P" as the first character in
the tire size means a passenger
vehicle tire engineered to
standards set by the U.S. Tire and
Rim Association. (2) Tire Width
:The 3-digit
number indicates the tire section
width in millimeters from sidewall
to sidewall.
(3) Aspect Ratio
:A 2-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size aspect
ratio is 75, as shown in item (3) of
the illustration, it would mean
that the tire's sidewall is
75 percent as high as it is wide.
(4) Construction Code
:A letter
code is used to indicate the type
of ply construction in the tire. The
letter "R" means radial ply
construction; the letter "D" means
diagonal or bias ply construction.
(5) Rim Diameter
:Diameter of
the wheel in inches.
(6) Service Description
:These
characters represent the load
index and speed rating of the tire.
The load index represents the load
carrying capacity a tire is certified