The 2007 Toyota Yaris is equipped with Engine Immobilizer System. It consists of transponder key coil/amplifier, unlock warning switch assembly, ECM and security indicator light.
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. Below schematic depicts the Toyota Yaris Engine Immobilizer System Wiring Diagram.
Through SFI communication, ECM receives ID verification results from transponder key ECU assembly. ECM also verifies ECUs. Then judges whether or not to enter immobilizer engine mode. When key is inserted in ignition key cylinder, key coil receives key code. Then amplifier amplifies ID code and outputs it to transponder key ECU assembly. Depending on operation of transponder key ECU, interior security indicator light comes on or starts blinking.