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(3) Without SMART key system
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2) Circuit Diagram
(1) With SMART key system
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(2) Without SMART key system
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2) Components
Test voltage(VCC 5V)
FUNCTION KEY VOLUE REMARK
MAIN 0.15 ~ 0.55V -
DECEL 0.7 ~ 1.1V -
ACCEL 1.6 ~ 2.0V -
RESUME 2.52 ~ 2.92V -
ECO 4.22 ~ 4.82V -
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Meter
clusterImmobilizer
antenna
Immobilizer key
Start motor
BCM
ECU
D20DTF
(10) Immobilizer control
a. Overview
The Immobilizer System provides an additional theft deterrent to the vehicle in which it is installed and
prevents it from being started by unauthorized persons. The transponder integrated in the key and the
engine control unit have the same code. When the ignition key with the integrated transponder is turned
to the ON position, the ECU (Engine Control Unit) checks the crypto code of the key and, if correct,
allows the vehicle to start the engine.
For details, refer to Chapter "BCM".
b. Components
Basic components (ignition key system)
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0000-00
Key approval process
When turning the ignition switch to ON position, the power is supplied to BCM and ECU. ECU
communicate with the immobilizer key to check if it is valid crypto code. If it is valid, ECU start to control
the engine when turning the ignition switch to START position.
The system has 10 seconds of valid time-out period. If the engine does not start in this period, the key
approval process should be done again.
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Smart key
slot
Smart key
Start motor
Meter
cluster
BCM
SKMD20DTF
ECU
c. Components for immobilizer with Smart key system
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Key approval process in Smart key system equipped vehicle
The key approval consists of two processes; immobilizer key approval and Smart key
approval.
Immobilizer key approval: When inserting the Smart key into Smart key slot, the power is supplied to the
key slot. SKM communicate with the Smart key in key slot to check if it has valid crypto code. If it is valid,
ECU start to control the engine when pressing the Engine Start/Stop button. The system has 10
seconds of valid time-out period. If the engine does not start in this period, the key approval process
should be done again.
Smart key approval: When pressing the Engine Start/Stop button or depressing the brake pedal without
Smart key inserted into the key slot, SKM communicate with the Smart key to check if it has valid crypto
code. If it is valid, the engine can be started.