Engine Immobiliser System (For Sedan) System Description

Vehicle Interior. Yaris. Ncp93, 131
Theft Deterrent Keyless Entry. Yaris. Ncp93, 131

  1. ENGINE IMMOBILISER SYSTEM DESCRIPTION

  1. FUNCTIONS OF MAIN COMPONENTS

  1. SYSTEM FUNCTION

Engine Immobiliser System (For Sedan) -- System Description



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.

FUNCTIONS OF MAIN COMPONENTS

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

SYSTEM FUNCTION
  1. When the transponder key ECU assembly 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 faint electric wave. Upon receiving the faint electric 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 ECU. The ECU compares 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 the SFI communication.
  2. After the identification results show that the key's ID code matches the vehicle's ID code and the ECU has confirmed that they match: 1) the immobiliser system is canceled and the engine starting controls (fuel injection control and ignition control) enter standby mode; and 2) the ECU transmits a security indicator signal that communicates "indicator OFF" to the transponder key ECU. Then, the transponder key ECU turns OFF the security indicator light.