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 immobilizer control 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 immobilizer control 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 immobilizer control module. A voltage creates and is read by the ECM through the immobilizer control module when the identification code signal is introduced to the magnetic field generated by the coils of the immobilizer control 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 immobilizer control 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 immobilizer control module mounts to the steering column. The immobilizer control 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 immobilizer control module makes no determination as to the validity of the transponder key while the immobilizer control 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 immobilizer control module or any wiring harness will not result in a successful bypass of the system. The immobilizer control module cannot be disassembled. Additionally, the immobilizer control module must be serviced as an assembly.

### Electronic Control Module (ECM)

The ECM verifies that the transponder identification code received from the immobilizer control module is correct. The immobilizer control module can learn up to 5 transponder identification codes. If the transponder identification code is correct, the ECM enables the fuel delivery system.

The ECM disables the fuel delivery systems if any of the following conditions occur:

• | The transponder identification code is incorrect.

• | No passwords are received - there is no communication with the ECM.

### 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.

### SECURITY Indicator Operation

The immobilizer control module can command the instrument cluster to illuminate the SECURITY indicator only when the ignition key is in the ON position. The security indicator is a malfunction indicator and does not illuminate during the bulb check when the ignition is turned to ON. The SECURITY indicator can indicate both malfunctions (Indicator on steady) and tamper (Indicator flashing - indicating unauthorized operation). Under the following conditions the SECURITY indicator may be commanded to illuminate.

#### SECURITY Indicator Stays Illuminated and Engine Starts

If the immobilizer control module was unable to measure the ignition key transponder value or the ECM lost communication with the immobilizer control module while the engine was last running, the indicator will remain illuminated during subsequent ignition cycles. This is to remind the driver that the vehicle theft deterrent system will not be functioning until the problem is corrected.

#### SECURITY Indicator Illuminates when Engine is Running

If the immobilizer control module is unable to measure the ignition key transponder value or the ECM loses communication with the immobilizer control module while the engine is running, the indicator will be illuminated. If the key is turned to OFF, the vehicle will be fail enabled and will start if the condition still exists at the next attempt to start the vehicle.

#### SECURITY Indicator Illuminated and Engine Does Not Start

The immobilizer control module or the ECM has detected a problem with the theft deterrent system. The immobilizer control module is unable to measure the ignition key transponder value.

#### SECURITY Indicator Flashes and Engine Does Not Start

The immobilizer control module has measured an incorrect transponder value when the ignition key is turned to the ON position. The transponder has not been learned by the immobilizer control module. This is considered a tamper condition by the immobilizer control module.