2021 MAZDA MODEL CX-3 ECU

NOTE
The keys carry a unique electronic code.
For this reason, and to assure your
safety, obtaining a replacement key
requires some waiting time. They are
only available through an Authorized
Mazda Dealer.
Always keep a spare key in case one is
lost. If a key is lost, consult an
Authorized Mazda Dealer as soon as
possible.
If you lose a key, an Authorized Mazda
Dealer, will reset the electronic codes of
your remaining keys and immobilizer
system. Bring all the remaining keys to
the Authorized Mazda Dealer to reset.
Starting the vehicle with a key that has
not been reset is not possible.
▼ Operation
NOTE
The engine may not start and security
indicator light may illuminate or flash if
the key is placed in an area where it is
difficult for the system to detect the
signal, such as on the dashboard or in
the glove compartment. Move the key to
a location within the signal range,
switch the ignition off, and then restart
the engine.
Signals from a TV or radio station, or
from a transceiver or mobile telephone
could interfere with your immobilizer
system. If you are using the proper key
and the engine fails to start, check the
security indicator light.
Arming
The system is armed when the ignition is
switched from ON to off.
The security indicator light in the
instrument cluster flashes every 2 seconds
until the system is disarmed.

Disarming
The system is disarmed when the ignition
is switched ON with the correct
programmed key. The security indicator
light illuminates for about 3 seconds and
then turns off. If the engine does not start
with the correct key, and the security
indicator light remains illuminated or
flashing, try the following:
Make sure the key is within the
operational range for signal transmission.
Switch the ignition off, and then restart the
engine. If the engine does not start after 3
or more tries, contact an Authorized
Mazda Dealer.
NOTE
If the security indicator light flashes
continuously while you are driving, do
not shut off the engine. Go to an
Authorized Mazda Dealer, and have it
checked. If the engine is shut off while
the indicator light is flashing, you will
not be able to restart it.
Because the electronic codes are reset
when the immobilizer system is repaired,
the keys are needed. Make sure to bring
all the keys to an Authorized Mazda
Dealer, so that they can be programmed.
Before Driving
Security System
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Theft-Deterrent System*
If the theft-deterrent system detects an
inappropriate entry into the vehicle, which
could result in the vehicle or its contents
being stolen, the alarm alerts the
surrounding area of an abnormality by
sounding the horn and flashing the hazard
warning lights.

The system will not function unless it's
properly armed. So when you leave the
vehicle, follow the arming procedure
correctly.
▼ Operation
System triggering conditions
The horn sounds intermittently and the
hazard warning lights flash for about 30
seconds when the system is triggered by
any one of the following:
Unlocking a door with
the auxiliary key,
door lock switch, or an inside door-lock
knob.
Forcing open a door, the hood or the
liftgate.
Opening the hood by operating the hood
release handle.
Switching the ignition ON without using
the push button start.
If the system is triggered again, the lights
and horn will activate until the driver's
door or the liftgate is unlocked with the
transmitter.
(With the advanced keyless function)
The lights and horn can also be
deactivated by pressing the request switch
on a door.
NOTE
The liftgate does not open while the
theft-deterrent system is operating.
If the battery goes dead while the
theft-deterrent system is armed, the horn
will activate and the hazard warning
lights will flash wh en the battery is
charged or replaced.
▼ How to Arm the System
1. Close the windows and the moonroof*
securely.
2. Switch the ignition OFF.
3. Make sure the hood, the doors, and the liftgate are closed.
4. Press the lock button on the transmitter or lock the driver's door from the
outside with the auxiliary key.
The hazard warning lights will flash
once.
The following method will also arm
the theft-deterrent system:
Press the door-lock switch “
” while
any door is open and then close all of
the doors.
(With the advanced keyless function)
Press a request switch.

The security indicator light in the
instrument cluster flashes twice per
second for 20 seconds.
5. After 20 seconds, the system is fully armed.
Before Driving
Security System
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NOTE
The theft-deterrent system can also be
armed by activating the auto relock
function with all the doors, the liftgate
and the hood closed.
Refer to Transmitter on page 3-5.
The system will disarm if one of the
following operations takes place within
20 seconds after pressing the lock
button:
Unlocking any door.
Opening any door.
Opening the hood.
Switching the ignition ON.
(With the advanced keyless function)
Pressing the electric liftgate opener
while the key is being carried.
To rearm the system, do the arming
procedure again.
When the doors are locked by pressing
the lock button on the transmitter or
using the auxiliary key while the
theft-deterrent system is armed, the
hazard warning lights will flash once to
indicate that the system is armed.
▼ To Tu r n O f f a n A r m e d S y s t e m
An armed system can be turned off using
any one of the following methods:
Pressing the unlock button on the
transmitter.
Starting the engine with the push button
start.
(With the advanced keyless function)
Pressing a request switch on the
doors.
The hazard warning lights will flash twice.
NOTE
When the doors are unlocked by pressing
the unlock button on the transmitter while
the theft-deterrent system is turned off, the
hazard warning lights will flash twice to
indicate that the system is turned off.
▼ To S t o p t h e A l a r m
A triggered alarm can be turned off using
any one of the following methods:
Pressing the unlock button on the
transmitter.
Starting the engine with the push button
start.
(With the advanced keyless function)
Pressing a request switch on the
doors.
Pressing the electric liftgate opener
while the key is being carried.
The hazard warning lights will flash twice.
Before Driving
Security System
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Hazardous Driving
WARNING
Be extremely careful if it is necessary to
downshift on slippery surfaces:
Downshifting into lower gear while driving
on slippery surfaces is dangerous. The
sudden change in tire speed could cause
the tires to skid. This could lead to loss of
vehicle control and an accident.
When driving on ice or in water, snow,
mud, sand, or similar hazards:
Be cautious and allow extra distance for
braking.
Avoid sudden braking and sudden
maneuvering.
Do not pump the brakes. Continue to
press down on the brake pedal.
Refer to Antilock Brake System (ABS)
on page 4-65.
If you get stuck, select a lower gear and
accelerate slowly. Do not spin the front
wheels.
For more traction in starting on slippery
surfaces such as ice or packed snow, use
sand, rock salt, chains, carpeting, or
other nonslip material under the front
wheels.
NOTE
Use snow chains only on the front wheels.
Floor Mat
We recommend the use of Genuine
Mazda floor mats.
WA R N I N G
Make sure the floor mats are hooked on the
retention pins to prevent them from
bunching up under the foot pedals:
Using a floor mat that is not secured is
dangerous as it will interfere with the
accelerator and brake pedal operation,
which could result in an accident.
Do not install two floor mats, one on top of
the other, on the driver's side:
Installing two floor mats, one on top of the
other, on the driver's side is dangerous as
the retention pins can only keep one floor
mat from sliding forward.
Loose floor mat(s) will interfere with the
foot pedals and could result in an accident.
If using an all-weather mat for winter use
always remove the original floor mat.
When setting a floor mat, position the
floor mat so that its grommets are inserted
over the pointed end of the retention posts.
Before Driving
Driving Tips
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Chains may scratch or chip aluminum
wheels.
NOTE
If your vehicle is equipped with the tire
pressure monitoring system, the system
may not function correctly when using
tire chains.
Install the chains on the front tires only.
Do not use chains on the rear tires.
Please consult an Authorized Mazda
Dealer.
Installing the chains
1. If your vehicle is equipped with wheel covers remove them, otherwise the
chain bands will scratch them.
2. Secure the chains on the front tires as
tightly as possible.
Always follow the chain
manufacturer's instructions.
3. Retighten the chains after driving 1/2―1 km (1/4 ―1/2 mile).
Driving In Flooded Area
WA R N I N G
Dry off brakes that have become wet by
driving slowly, releasing the accelerator
pedal and lightly applying the brakes
several times until the brake performance
returns to normal:
Driving with wet brakes is dangerous.
Increased stopping distance or the vehicle
pulling to one side when braking could
result in a serious accident. Light braking
will indicate whether the brakes have been
affected.
CAUTION
Do not drive the vehicle on flooded roads
as it could cause short circuiting of
electrical/electronic parts, or engine
damage or stalling from water absorption.
If the vehicle has been immersed in water,
consult an Authorized Mazda Dealer.
Before Driving
Driving Tips
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Ignition Switch
▼Push Button Start Positions
The system operates only when the driver
is in the vehicle or within operational
range while the key is being carried.
Each time the push button start is pressed,
the ignition switches in the order of off,
ACC, and ON. Pressing the push button
start again from ON switches the ignition
off.
Push button start Indicator light
NOTE
The engine starts by pressing the push
button start while depressing the clutch
pedal (manual transaxle) or the brake
pedal (automatic transaxle). To switch
the ignition position, press the push
button start without depressing the
pedal.
Do not leave the ignition switched ON
while the engine is not running. Doing
so could result in the battery going
dead. If the ignition is left in ACC (For
automatic transaxle, the selector lever is
in the P position, and the ignition is in
ACC), the ignition switches off
automatically after about 25 minutes.
Off
The power supply to electrical devices
turns off and the push button start
indicator light (amber) also turns off.
WA R N I N G
Before leaving the driver's seat, always
switch the ignition
off, set the parking
brake, and make sure the selector lever is in
P (automatic transaxle) or in 1st gear or R
(manual transaxle):
Leaving the driver's seat without switching
the ignition off, setting the parking brake,
and shifting the selector lever to P
(automatic transaxle) or to 1st gear or R
(manual transaxle) is dangerous.
Unexpected vehicle movement could occur
which could result in an accident.
In addition, if your intention is to leave the
vehicle for even a short period, it is
important to switch the ignition off, as
leaving it in another position will disable
some of the vehicle's security systems and
run the battery down.
ACC (Accessory)
Some electrical accessories will operate
and the indicator light (amber) illuminates.
NOTE
The keyless entry system does not function
while the push button start has been
pressed to ACC, and the doors will not
lock/unlock even if they have been locked
manually.
ON
This is the normal running position after
the engine is started. The indicator light
(amber) turns off. (The indicator light
When Driving
Start/Stop Engine
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After pressing the push button start
and before the engine starts, the
operation sound of the fuel pump
motor from near the fuel tank can be
heard, however, this does not
indicate a malfunction.
8. After starting the engine, let it idle for about ten seconds.
NOTE
Whether the engine is cold or warm,
it should be started without the use
of the accelerator.
If the engine does not start the first
time, refer to Starting a Flooded
Engine under Emergency Starting. If
the engine still does not start, have
your vehicle inspected by an
Authorized Mazda Dealer (page
7-20).
▼Engine Start Function When Key
Battery is Dead
CAUTION
When starting the engine by holding the
transmitter over the push button start due
to a dead key battery or a malfunctioning
key, be careful not to allow the following,
otherwise the signal from the key will not
be received correctly and the engine may
not start.

Metal parts of other keys or metal objects
touch the key.
Spare keys or keys for other vehicles
equipped with an immobilizer system
touch or come near the key.
 Devices for electronic purchases, or
security passage touch or come near the
key.
If the engine cannot be started due to a
dead key battery, the engine can be started
using the following procedure:
1. Continue to depress the brake pedal firmly until the en gine has completely
started.
2. (Manual transaxle)
Continue to depress the clutch pedal
firmly until the en gine has completely
started.
3. Make sure that the push button start
indication light (green) flashes.
4. Align the center area of the emblem on the transmitter with the center area of
the push button st art while the push
button start indicator light (green)
flashes.

Indicator light
Push button start
Key
Emblem
When Driving
Start/Stop Engine
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SignalWarning Lights Page
Low Fuel Warning Light 7-33
Check Fuel Cap Warning Light*17-33
Seat Belt Warning Light (Front seat) 7-33
Door-Ajar Warning Light7-33
*Low Washer Fluid Level Warning Light7-33
(Amber)
*Smart Brake Support/Smart C
ity Brake Support (SBS/SCBS)
Wa r n i n g L i g h t 7-33
*1 The light turns on when the ignition is switched on for an operation check, and turns off a few seconds later or
when the engine is started. If the light does not turn on or remains turned on, have the vehicle inspected at an
Authorized Mazda Dealer.
*2 The light turns on continuously when the parking brake is applied.
▼ Indicator Lights
These lights turn on or flash to notify the us
er of the system operation status or a system
malfunction.
Signal Indicator Lights Page
*Front Passenger Air Bag Deactivation Indicator Light*12-66
(Green)KEY Indicator Light 3-9
Security Indicator Light*13-37
Wrench Indicator Light*14-25
(Blue)
Low Engine Coolant Temperature Indicator Light 4-26
*Shift Position Indication
4-31
Lights-On Indicator Light
4-40
When Driving
Instrument Cluster and Display
*Some models.4-23
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