2021 CADILLAC CT4 headlamp

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 331
When the electrical load is too heavy
a circuit breaker opens, protecting the
circuit until overcurrent condition is
removed. This greatly reduces the
chance of circuit overload and fire
caused by electrical problems.
Fuses and circuit breakers protect
electrical devices in the vehicle.
Replace a blown or open fuse with a
new one of the identical size and
rating.
If there is a problem on the road and
a fuse needs to be replaced, the
same amperage fuse can be borrowed.
Choose some feature of the vehicle
that is not needed to use and replace
it as soon as possible.
Headlamp Wiring
An electrical overload may cause the
lamps to go on and off, or in some
cases to remain off. Have the
headlamp wiring checked right away if
the lamps go on and off or remain off.
Windshield Wipers
If the wiper motor overheats due to
heavy snow or ice, the windshield
wipers will stop. Wiper function is
available immediately after the wiper
switch is set to off, and back to on.
To protect the wiper motor from
overheating, the wipers may slow
down when the windshield is dry for a
long period of time. If a period of dry
operation, or little moisture, exceeds
10 minutes, the wipers may switch to
intermittent operation, and remain
there. When moisture is again
detected on the windshield, wiper
operation will return to the operator
selected speed.
Although the circuit is protected from
electrical overload, overload due to
heavy snow or ice may cause wiper
linkage damage. Always clear ice and
heavy snow from the windshield
before using the windshield wipers.
If the overload is caused by an
electrical problem and not snow or
ice, be sure to get it fixed.
Fuses and Circuit Breakers
The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit
breakers. This greatly reduces the
chance of damage caused by electrical
problems.
{Danger
Fuses and circuit breakers are
marked with their ampere rating.
Do not exceed the
specified amperage rating when
replacing fuses and circuit breakers.
Use of an oversized fuse or circuit
breaker can result in a vehicle fire.
You and others could be seriously
injured or killed.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 333
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 Fuses
Usage
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
23 Transmission control module/Transmission
reverse lock out
24 Active engine mount
25 –

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
336 VEHICLE CARE
FusesUsage
13 –
14 –
15 –
16 –
17 –
18 Display/Infotainment/ USB/Multi-function
control module
19 Airbag/ Automatic occupant sensing /
Data link connection/
Wireless charging
module/ Virtual key
module
20 Power steering column module/
Electronic steering
column lock 2
21 Driver monitor system/Performance
data recorder
22 –
23 –
24 – Fuses
Usage
25 USB
26 –
27 –
28 –
29 –
30 –
31 Headlamp level
32 –
33 Body ignition/IP ignition
34 Exhaust valve
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 Fuses
Usage
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 –

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
358 VEHICLE CARE
should be replaced. If the wheel leaks
air, replace it. Some aluminum wheels
can be repaired. See your dealer if any
of these conditions exist.
Your dealer will know the kind of
wheel that is needed.
Each new wheel should have the same
load-carrying capacity, diameter,
width, offset, and be mounted the
same way as the one it replaces.
Replace wheels, wheel bolts, wheel
nuts, or Tire Pressure Monitor System
(TPMS) sensors with new GM original
equipment parts.
{Warning
Using the wrong replacement
wheels, wheel bolts, or wheel nuts
can be dangerous. It could affect
the braking and handling of the
vehicle. Tires can lose air, and
cause loss of control, causing a
crash. Always use the correct wheel,
wheel bolts, and wheel nuts for
replacement.
Caution
The wrong wheel can also cause
problems with bearing life, brake
cooling, speedometer or odometer
calibration, headlamp aim, bumper
height, vehicle ground clearance,
and tire or tire chain clearance to
the body and chassis.
Used Replacement Wheels
{Warning
Replacing a wheel with a used one
is dangerous. How it has been used
or how far it has been driven may
be unknown. It could fail suddenly
and cause a crash. When replacing
wheels, use a new GM original
equipment wheel.
Tire Chains
{Warning
If the vehicle has 235/40R18 or
235/35R19 size tires, do not use tire
chains. There is not enough
clearance. Tire chains used on a
vehicle without the proper amount
of clearance can cause damage to
the brakes, suspension, or other
vehicle parts. The area damaged by
the tire chains could cause loss of
control and a crash. Use another
type of traction device only if its
manufacturer recommends it for
the vehicle's tire size combination
and road conditions. Follow that
manufacturer's instructions. To
avoid vehicle damage, drive slow
and readjust or remove the traction
device if it contacts the vehicle. Do
not spin the wheels. If traction
devices are used, install them on
the rear tires.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
SERVICE AND MAINTENANCE 389
The following list is intended to
explain the services and conditions to
look for that may indicate services are
required.
Battery
The 12-volt battery supplies power to
start the engine and operate any
additional electrical accessories.
.To avoid break-down or failure to
start the vehicle, maintain a battery
with full cranking power.
.Trained dealer technicians have the
diagnostic equipment to test the
battery and ensure that the
connections and cables are
corrosion-free.
Belts
.Belts may need replacing if they
squeak or show signs of cracking or
splitting.
.Trained dealer technicians have
access to tools and equipment to
inspect the belts and recommend
adjustment or replacement when
necessary. Brakes
Brakes stop the vehicle and are crucial
to safe driving.
.Signs of brake wear may include
chirping, grinding, or squealing
noises, or difficulty stopping.
.Trained dealer technicians have
access to tools and equipment to
inspect the brakes and recommend
quality parts engineered for the
vehicle.
Fluids
Proper fluid levels and approved fluids
protect the vehicle’s systems and
components. See Recommended Fluids
and Lubricants 0391 for GM approved
fluids.
.Engine oil and windshield washer
fluid levels should be checked at
every fuel fill.
.Instrument cluster lights may come
on to indicate that fluids may be
low and need to be filled. Hoses
Hoses transport fluids and should be
regularly inspected to ensure that
there are no cracks or leaks. With a
multi-point inspection, your dealer
can inspect the hoses and advise if
replacement is needed.
Lamps
Properly working headlamps,
taillamps, and brake lamps are
important to see and be seen on
the road.
.Signs that the headlamps need
attention include dimming, failure
to light, cracking, or damage. The
brake lamps need to be checked
periodically to ensure that they light
when braking.
.With a multi-point inspection, your
dealer can check the lamps and
note any concerns.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
422 INDEX
Appearance CareExterior . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Apple CarPlay and Android Auto . . . . . . . . . . . . . . . . . . . . . . 174
Assistance Systems for Driving . . . . 283
Assistance Systems for Parking and Backing . . . . . . . . . . . . . . . . . . . . . . . 277
Audio Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Auto Stop
Stop/Start System . . . . . . . . . . . . . . . . 221
Automatic Dimming Mirrors . . . . . . . . . . . . . . . . . . 25
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . 17
Emergency Braking (AEB) . . . . . . . . 285
Headlamp System . . . . . . . . . . . . . . . . 128
Transmission . . . . . . . . . . . . . . . . 227, 229
Transmission Fluid . . . . . . . . . . . . . . . 315
Vehicle Hold Light . . . . . . . . . . . . . . . . 101
Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . 234, 235
Automatic Vehicle Hold (AVH) . . . . 239
Avoiding Untrusted Media Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145B
Battery
Exterior Lighting BatterySaver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Load Management . . . . . . . . . . . . . . . . 132
Power Protection . . . . . . . . . . . . . . . . . . 133
Battery - North America . . . . . .326, 366
Blade Replacement, Wiper . . . . . . . . . 327
Bluetooth Overview . . . . . . . . . . . . . . . . . . . . 169, 170
Bluetooth Audio . . . . . . . . . . . . . . . . . . . . 148
Brake Electric Boost . . . . . . . . . . . . . . . . . . . . . 236
Parking, Electric . . . . . . . . . . . . . . . . . . 237
System Warning Light . . . . . . . . . . . . . 99
Brake Pad Life System . . . . . . . . . . . . . . 324
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323 Antilock . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Pad Life System . . . . . . . . . . . . . . . . . . . 324
Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Automatic Emergency (AEB) . . . . . 285
Braking System
Front Pedestrian (FPB) . . . . . . . . . . . 287
Break-In, New Vehicle . . . . . . . . . . . . . . 218
Buckle To Drive . . . . . . . . . . . . . . . . . . . . . . 41 Bulb Replacement
Front Turn Signal Lamps . . . . . . . . 330
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . 330
Headlamp Aiming . . . . . . . . . . . . . . . . 329
Headlamps . . . . . . . . . . . . . . . . . . . . . . . . 329
High Intensity Discharge(HID) Lighting . . . . . . . . . . . . . . . . . . . 330
Buying New Tires . . . . . . . . . . . . . . . . . . . 354
C
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
California Perchlorate MaterialsRequirements . . . . . . . . . . . . . . . . . . . 306
California Proposition 65 Warning . . . . . . . . . . . . .305, 326, 366, Back Cover
Canadian Vehicle Owners . . . . . . . . . . . . . 1
Capacities and Specifications . . . . . . 396
Carbon Monoxide Engine Exhaust . . . . . . . . . . . . . . . . . . . 226
Trunk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Winter Driving . . . . . . . . . . . . . . . . . . . . 213
Cargo Management System . . . . . . . . . . . . . . 80
Tie-Downs . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Caution, Danger, and Warning . . . . . . . . 2
Center Console Storage . . . . . . . . . . . . . . 79

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
INDEX 425
F
Filter,Engine Air Cleaner . . . . . . . . . . . . . . . . 316
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . 128
Flashers, Hazard Warning . . . . . . . . . . 129
Flat Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
Floor Mats . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Fluid Automatic Transmission . . . . . . . . . 315
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Washer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . 24
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Frequency Statement Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409
Front Pedestrian Braking (FPB) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Front Seats
Heated and Ventilated . . . . . . . . . . . . 37
Front Turn Signal Lamps . . . . . . . . . . 330
Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . . . 294
Economy, Driving for Better . . . . . 203
Filling a Portable FuelContainer . . . . . . . . . . . . . . . . . . . . . . . . 296
Filling the Tank . . . . . . . . . . . . . . . . . . . 295
Foreign Countries . . . . . . . . . . . . . . . . . 294 Fuel (cont'd)
Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Low Fuel Warning Light . . . . . . . . . 105
Prohibited Fuels . . . . . . . . . . . . . . . . . . 294
Recommended . . . . . . . . . . . . . . 293, 294
Top Tier . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
Fuses
Engine Compartment FuseBlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Fuses and Circuit Breakers . . . . . . . 331
Instrument Panel Fuse Block . . . . 334
Rear Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
G
Garage Door Opener . . . . . . . . . . . . . . . . 122Programming . . . . . . . . . . . . . . . . . . . . . . 122
Gas Strut(s) . . . . . . . . . . . . . . . . . . . . . . . . . 328
Gauges Engine CoolantTemperature . . . . . . . . . . . . . . . . . . 94, 95
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Odometer . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Speedometer . . . . . . . . . . . . . . . . . . . . . . . 93
Tachometer . . . . . . . . . . . . . . . . . . . . . . . . 93
Trip Odometer . . . . . . . . . . . . . . . . . . . . . 93
Warning Lights and Indicators . . . 87 General Information
Service and Maintenance . . . . . . . . 379
Towing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
Vehicle Care . . . . . . . . . . . . . . . . . . . . . . . 305
Global Positioning System (GPS) . . . . . . . . . . . . . . . . . . . . . . 161
Glove Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
GM Mobility Reimbursement
Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
Guidance Problems with the Route . . . . . . . . . 162
H
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . 330
Hazard Warning Flashers . . . . . . . . . . 129
HD Radio Technology . . . . . . . . . . . . . . 143
Head Restraints . . . . . . . . . . . . . . . . . . . . . . 31
Head-up Display . . . . . . . . . . . . . . . . . . . . 112
Headlamps
Aiming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Automatic . . . . . . . . . . . . . . . . . . . . . . . . . 128
Bulb Replacement . . . . . . . . . . . . . . . . 329
Daytime RunningLamps (DRL) . . . . . . . . . . . . . . . . . . . . 128
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . 128
High Intensity Discharge (HID) Lighting . . . . . . . . . . . . . . . . . . . 330
High-Beam On Light . . . . . . . . . . . . . . 105