System Description

WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

ENGINE IMMOBILIZER SYSTEM DESCRIPTION
The engine immobilizer 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.

FUNCTION OF MAIN COMPONENT

MAIN COMPONENT FUNCTION

Component	Outline
Transponder key coil/amplifier	When key is inserted into ignition key cylinder, key coil receives key code. Then amplifier amplifies ID code and outputs it to transponder key ECU.
Unlock warning switch assembly	Detects whether key is in ignition key cylinder and outputs results to transponder key ECU
ECM	Through SFI communication, ECM receives ID verification results from transponder key ECU. ECM also verifies ECUs. Then ECM judges whether or not to immobilize engine.
Security indicator light	Depending on operation of transponder key ECU, interior security indicator light comes on or starts blinking

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 and 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 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 the results to the ECM using 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 engine immobilizer system is canceled and the engine starting controls (fuel injection control and ignition control) enter standby mode; and 2) the ECU receives a security indicator light signal, and turns the security indicator light OFF.