Antitheft and Alarm Systems: Description and Operation

ENGINE IMMOBILISER: ENGINE IMMOBILISER SYSTEM: SYSTEM DIAGRAM






ENGINE IMMOBILISER: ENGINE IMMOBILISER SYSTEM: SYSTEM DESCRIPTION

1. ENGINE IMMOBILISER SYSTEM DESCRIPTION

The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ECU that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the transponder key ECU sends a signal to the ECM to prohibit fuel delivery and ignition, effectively disabling the engine.

2. FUNCTION OF MAIN COMPONENT





3. SYSTEM FUNCTION

When the transponder key ECU detects that the unlock warning switch is ON, the ECU provides current to the transponder key coil and produces a faint electric wave. A transponder chip in the key grip receives the wave. Upon receiving the wave, the transponder chip outputs a key ID code signal. The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the transponder key ECU. The transponder key ECU matches the key's ID code with the vehicle's ID code, which was previously registered in the transponder key ECU. If the ID codes match, the transponder key ECU turns OFF the security indicator. Then when the ignition key cylinder is turned, the code match results are sent through the transponder key ECU to the ECM. After the identification results show that the key's ID code matches the vehicle's ID code and the transponder key ECU has confirmed their match, the immobiliser system is canceled and the engine starting controls (fuel injection control and ignition control) enter standby mode.