For 1990-2009 cars

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 if 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. Refer to System Operation for additional information on the operating characteristics of the immobilizer system. 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 key ring is not addressed (maximum 2 - 3 cm reading distance). The transmission of the ignition key transponder identification code is secure under any ambient condition.

### Immobilizer Control Module

The theft deterrent module mounts to the steering column. The theft deterrent module contains an antenna arranged in a ring around the ignition lock cylinder. The transponder enters the very limited reading range (2 - 3 cm) of the antenna with the ignition in the RUN position when the transponder key inserts in the ignition lock cylinder. This guarantees that only the key that is inserted in the ignition lock cylinder can have its transponder code audited. This excludes the possibility of interference from other transponder keys in the vicinity. The theft deterrent module makes no determination as to the validity of the transponder key while the theft deterrent module receives the signal from the transponder key. This is done solely by the ECM. The ECM performs all decision making processes. Therefore, any theft attempt by hot-wiring the theft deterrent module or any wiring harness will not result in a successful bypass of the system. The theft deterrent module cannot be disassembled. Additionally, the theft deterrent module must be serviced as an assembly.

### Transponder

The ignition key head contains the transponder. The transponder emits a magnetic field. This magnetic field interacts with the magnetic field generated by the coils of the theft deterrent module creating a voltage which is read by the ECM through the theft deterrent module. The transponder is a small magnet. Therefore, the transponder does not require battery power. The transponder never requires replacement under normal operating conditions.

The ignition key head (1) contains the transponder (2). The transponder does not require battery power. The transponder (2) never requires replacement under normal usage. Service the transponder (2) and the ignition key (1) only as an assembly. Reprogram the system with a scan tool when replacing a key.