Theft Deterrent System Operation

The immobilizer system is standard equipment on this vehicle. The immobilizer system design prevents vehicle theft by interrupting the engine operation. Many other ignition-related theft deterrent systems deter starting of the engine it the key is determined to be incorrect. The immobilizer system allows the vehicle to start for a very short period regardless of the ignition key (assuming the mechanical cuts are correct). The engine operating functions interrupt and the engine stalls if the immobilizer system does not recognize the transponder identification code of the ignition key.

The immobilizer system and the content theft deterrent system operate independent of each other. The immobilizer system and the content theft deterrent system do not interact. The system includes the following components:
^ The ignition key.
^ The column-mounted theft deterrent module with integrated antenna.
^ The transponder.
^ The EBTCM.
^ The ECM.

The immobilizer system design interrupts the engine operation if the immobilizer system does not recognize the proper transponder input from the ignition key. Many systems prevent the engine to start until the proper key is used. The immobilizer system allows the engine to start. The immobilizer then performs security checks of the key. The ECM requests the character of the transponder identification code from the theft deterrent module approximately 20 - 130 milliseconds after the engine starts. The engine control functions interrupt immediately (maximum 1.5 seconds after the ignition is On) and the engine stalls with an incorrect code. The engine functions remain uninterrupted with a correct code.

An invariable identification code emits from the transponder (installed in the ignition key head) to achieve this. The invariable identification code is read without battery contact via the theft deterrent module. A voltage creates and is read by the ECM through the theft deterrent module when the identification code signal is introduced to the magnetic field generated by the coils of the theft deterrent module. The ECM compares this value to a value stored in the memory. The ECM then determines whether to allow continued engine operation.

The range of the transmitting and receiving antenna on the theft deterrent module is so that a second key with transponder on a keyring is not addressed (maximum 2 - 3 cm reading distance). The transmission of the ignition key transponder identification code is secure under any ambient condition.