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Home >> Subaru >> 2015 >> BRZ Limited, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 44 (Engine Immobilizer System (W/O Entry Start)) >> Engine Immobilizer System (Without Entry & Start System) >> Description Of Functions

Description Of Functions

WARNING: This page is about a different car, the 2014 Subaru BRZ. However, it is still accessible from the selected car via links, so may be relevant.
  1. Description of the engine immobilizer system
    1. The engine immobilizer system records the key ID in the main body ECM (multiplex network body computer). If the key ID and the code recorded in the main body ECM do not match, the engine immobilizer system prohibits the engine from starting.
  2. Functions of the main parts
    Components Summary
    Main body ECM (Network gateway computer) This checks if the key ID received from the transponder key amplifier matches the registered key ID. Concurrently, it communicates with the combination meter assembly(1) or the transponder ECM(2) and checks that the key ID (meter ID) recorded in the combination meter assembly(1) or transponder ECM(2) matches the ID (meter ID) recorded in the main body ECM. Based on the request from the engine control computer, it encrypts each collation result and registered ID (engine ID), and sends them to the engine control computer.
    Combination meter assembly(1) Based on the request from the main body ECM (network gateway computer), it encrypts the registered ID, and sends it to the main body ECM (network gateway computer).
    Transponder key ECM assembly(2) Based on the request from the main body ECM (network gateway computer), it encrypts the registered ID, and sends it to the main body ECM (network gateway computer).
    Transponder key amplifier This receives the key ID from the antenna coil, and outputs the key ID, which was amplified by the amplifier, to the main body ECM (network gateway computer).
    Engine control computer When the engine starts, this communicates with the main body ECM (network gateway computer), and receives the key ID, the meter ID collation result, and the encrypted ID (engine ID) of the main body ECM (network gateway computer). If any of them do not match, it stops (prohibits) the engine from starting.
    Unlock warning switch assembly This detects a key inserted in the key cylinder and outputs the result to the main body ECM (network gateway computer).
    (1) With a transponder ECM
    (2) Without a transponder ECM
  3. System functions
    1. When the main body ECM (network gateway computer) detects that the unlock warning switch assembly is ON, it powers the transponder key amplifier and generates a magnetic field around the antenna coil. The transponder chip inside the key grip outputs a key ID signal by the electromotive force generated by the magnetic field. The transponder key amplifier receives the key ID code signal, amplifies it by an amplifier, and sends it to the main body ECM (network gateway computer).

      The main body ECM (network gateway computer) checks if the key ID received from the transponder key amplifier matches the registered key ID. Concurrently, the main body ECM (network gateway computer) communicates with the combination meter assembly*1 or the transponder ECM*2 and checks that the ID (meter ID) recorded in the combination meter assembly*1 or transponder ECM*2 matches the ID (meter ID) recorded in the main body ECM (network gateway computer).

      When starting the engine, the engine control computer communicates with the main body ECM (network gateway computer), and checks the collation result between the key and the combination meter assembly*1 or the transponder ECM*2. Also, it checks if the ID (engine ID) recorded in the main body ECM (network gateway computer) matches, and if any does not match, it stops the engine from starting.

      *1: With a transponder ECM

      *2: Without a transponder ECM

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