Antitheft and Alarm Systems: Description and Operation

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 ECU sends a signal to the ECM to prohibit fuel delivery and ignition, effectively disabling the engine.
- When the ECU detects that the unlock warning switch is ON, the ECU provides current to the transponder key coil and produce a faint electric wave. A transponder chip in the key grip receives the faint electric wave. Upon receiving the faint electric wave, the transponder chip outputs a key ID codes signal. The transponder key coil receives this signal, the transponder key amplifies it, and then the signal is transmitted to the ECU. The ECU matches the key's ID code with the vehicle's ID code, which was previously registered in the ECU, and then communicates with the ECM using the SFI communication.
- After the identification results show that the key's ID code matches the vehicle's ID code and the ECU has confirmed their match: 1) the immobiliser system is canceled the engine and the engine starting systems (fuel injection control and ignition control) enter standby mode; and 2) the ECU turns off the security indicator light.