2021 MAZDA MODEL 3 HATCHBACK ECU

Modification and
Add-On Equipment
▼ Modi
fication and Add-On
Equipment
Mazda cannot guarantee the
immobilizer and the theft-deterrent
system's operation if the system has
been modi fied or if any add-on
equipment has been installed.
CAUTION
To avoid damage to the vehicle, do not
modify the system or install any add-on
equipment to the immobilizer and the
theft-deterrent systems or the vehicle.
Immobilizer System
▼ Immobilizer System
The immobilizer system allows the
engine to start only with a key the
system recognizes.

If someone attempts to start the
engine with an unrecognized key, the
engine will not start, thereby helping to
prevent vehicle theft.
If you have a problem with the
immobilizer system or the key, consult
an Authorized Mazda Dealer.
CAUTION

Radio equipment like this is
governed by laws in the United
States.
Changes or modi fications not
expressly approved by the party
responsible for compliance could
void the user's authority to operate
the equipment.
 To avoid damage to the key, do not:
 Drop the key.
 Get the key wet.
 Expose the key to any kind of
magnetic field.
 Expose the key to high
temperatures on places such as the
dashboard, under direct sunlight.
 If the engine does not start with the
correct key, and the security indicator
light keeps illuminating or flashing ,
the system may have a malfunction.
Consult an Authorized Mazda
Dealer.
Before Driving
Security System
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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 an
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 di fficult 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 o ff.
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 illu minates for about 3
seconds and then turns o ff.
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 o ff,
and then restart the engine. If the
engine does not start after 3 or more
tries, contact an Authorized Mazda
Dealer.
Before Driving
Security System
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Theft-Deterrent System*
▼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/trunk lid.
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/trunk lid is
unlocked with the transmitter.
(With the advanced keyless function)
The lights and horn can also be
deactivated by touching the sensing
area of the door release touch sensor.
NOTE
If the battery goes dead while the
theft-deterrent system is armed, the
horn will activate and the hazard
warning lights will flash when 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/trunk lid are
closed.
4. Press the lock button on the transmitter.
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)
Touch the sensing area of the door
lock touch sensor.

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/trunk lid 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.
To rearm the system, do the arming
procedure again.
When the doors are locked by
pressing the lock button on the
transmitter 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
ff an Armed System
An armed system can be turned o ff
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)
Touching the sensing area of the
door release touch sensor.
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 o ff, the hazard
warning lights will flash twice to
indicate that the system is turned o ff.
▼ To S t o p t h e A l a r m
A triggered alarm can be turned o
ff
using any one of the following
methods:
Pressing the unlock button or the
trunk button (4–door) on the
transmitter.
Starting the engine with the push
button start.
(With the advanced keyless
function)
Touching the sensing area of the
door release touch sensor.
Pressing the electric liftgate/trunk
lid opener while the key is being
carried.
The hazard warning lights will flash
twice.
Before Driving
Security System
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Floor Mat
▼Floor Mat
We recommend the use of Genuine
Mazda
floor mats.
WARNING
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
fl oor mat so that its grommets are
inserted over the pointed end of the
retention posts.
Rocking the Vehicle
▼ Rocking the Vehicle
WARNING
Do not spin the wheels at more than
56 km/h (35 mph), and do not allow
anyone to stand behind a wheel when
pushing the vehicle:
When the vehicle is stuck, spinning the
wheels at high speed is dangerous. The
spinning tire could overheat and
explode. This could cause serious
injuries.
CAUTION
Too much rocking may cause engine
overheating , transmission failure, and
tire damage.
If you must rock the vehicle to free it
from snow, sand or mud, depress the
accelerator slightly and slowly move
the shift lever/selector lever from 1 (D)
to R position.
Before Driving
Driving Tips
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WARNING
Use only the same size and type tires
(snow, radial, or non-radial) on all 4
wheels:
Using tires different in size or type is
dangerous. Your vehicle's handling
could be greatly a ffected and result in
an accident.
CAUTION
Check local regulations before using
studded tires.
NOTE
The tire pressure monitoring system
may not function correctly when using
tires with steel wire reinforcement in
the sidewalls (page 4-220).
▼ Tire Chains
Check local regulations before using
tire chains.
CAUTION

Chains may a ffect handling.
 Do not go faster than 50 km/h (30
mph) or the chain manufacturer's
recommended limit, whichever is
lower.
 Drive carefully and avoid bumps,
holes, and sharp turns.
 Avoid locked-wheel braking.
 Do not use chains on a temporary
spare tire; it may result in damage to
the vehicle and to the tire.
 Do not use chains on roads that are
free of snow or ice. The tires and
chains could be damaged.
 Chains may scratch or chip
aluminum wheels.
NOTE
The tire pressure monitoring 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).
Before Driving
Driving Tips
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Ignition Switch
▼Push Button Start Positions
The system operates only when the key
is within operational range.
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.
1. Indicator light
2. Push button start
NOTE
The engine starts by pressing the
push button start while depressing
the clutch pedal (manual
transmission) or the brake pedal
(automatic transmission). 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 transmission,
the selector lever is in the P position,
and the ignition is in ACC), the
ignition switches o ff automatically
after about 25 minutes.
O ff
The power supply to electrical devices
turns off and the indicator light
(amber) also turns off .
WARNING
Before leaving the driver's seat,
always switch the ignition o ff, set the
parking brake, and make sure the
selector lever is in P (automatic
transmission) position or in 1st gear
or R (manual transmission):
Leaving the driver's seat without
switching the ignition off, setting the
parking brake, and shifting the selector
lever to P (automat ic transmission)
position or to 1st gear or R (manual
transmission) 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.
When Driving
Start/Stop Engine
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▼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 engine has
completely started.
2. (Manual transmission)
Continue to depress the clutch
pedal firmly until the engine has
completely started.
(Automatic transmission)
Put the vehicle in park (P). If you
must restart the engine while the
vehicle is moving, shift into neutral
(N).
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 start
while the push button start
indicator light (green) flashes.

1. Indicator light
2. Push button start
3. Transmitter
4. Emblem

5. Make sure that the push button start indicator light (green) turns
on.
6. Press the push button start to start the engine.
When Driving
Start/Stop Engine
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