Engine Immobilizer Systems: Operation

Transponder chip is incorporated into grip area on top of ignition key. When ignition key is inserted into ignition lock cylinder, the transponder key coil receives and ignition key identification code from the transponder chip. The transponder key Electronic Control Unit (ECU) checks if ignition key is preregistered by checking the ignition key identification code and delivers the result to the Hybrid Vehicle (HV) control Electronic Control Unit (ECU). Transponder key ECU may also be referred to as transponder key computer. Hybrid vehicle control ECU may also be referred to as HV ECU. When hybrid vehicle control ECU confirms ignition key is registered, it transmits its own identification numbers to the transponder key ECU. The transponder ECU then calculates internally and delivers the calculated result back to the hybrid vehicle control ECU. Hybrid vehicle control ECU rechecks the calculated result against calculation stored in the hybrid vehicle control ECU. If calculations are the same, hybrid vehicle control ECU allows hybrid system operation and allows the engine to start. If calculations are not the same, hybrid vehicle control ECU will not allow hybrid system operation and the engine to start.

Engine immobilizer system is set each time ignition key is removed from ignition lock cylinder, or 20 seconds have elapsed after ignition switch is turned from ON to ACC or LOCK positions. When engine immobilizer system is set, the SECURITY indicator light will flash to indicate system is set. SECURITY indicator light is displayed as a vehicle icon near the clock at the center of instrument panel. See Figure. If replacing ignition keys, transponder key ECU or hybrid vehicle control ECU, engine immobilizer system components must be properly programmed. For information on programing of system components, see PROGRAMMING . If a problem exists in engine immobilizer system, a Diagnostic Trouble Code (DTC) may be stored in transponder key ECU.