Antitheft and Alarm Systems: Description and Operation

IMMOBILIZER SYSTEM
The immobilize system consists of the ignition key, the key ring antenna, the immobilize-ECU, and the ECM or PCM . The ignition key has a built-in transponder. The key ring antenna is installed on the steering lock key cylinder. Only the registered ignition key permits the engine to start, therefore, the engine can never be started by means of a forged key or by connecting the ignition wiring directly. The system is significantly safe and reliable against theft. In addition, the driver has only to turn the ignition switch to the "ON" position to activate the immobilize system. If the requirements for starting the engine are not satisfied, the engine will be immobilized. If a registered ignition key is lost, all your ignition keys need to be registered again using scan tool MB991502 (MUT-II) to ensure security. An additional ignition key can be registered as follows (only if no ignition keys are lost):

- Using scan tool MB991502 (MUT-II)
- By operating two ignition keys that have been already registered.

OPERATION
1. When the ignition switch is turned to ON position, the ECM or PCM sends a requirement for the encrypted code to the immobilize-ECU (at this time, the engine is remobilized).
2. When the immobilize-ECU receives the requirement from the ECM or PCM , the immobilize-ECU supplies power to the transponder inside the ignition key via the antenna. The energized transponder sends the encrypted code back to the immobilize-ECU via the antenna.
3. The immobilize-ECU judges the encrypted code with its code logic in itself. If they are identical, the immobilize-ECU sends the encrypted code to the ECM or PCM .
4. If the ECM < M/T> or PCM can not receive the encrypted code, the engine will be immobilized.

THEFT-ALARM SYSTEM
When the theft-alarm system has been armed if a door or trunk lid is opened, the horn will sound and headlight flash (high-beam) intermittently for a period of 180 seconds.
This system is controlled by the ETACS-ECU and front-ECU.
The system is composed of the components described below.

PANIC ALARM
With the theft alarm function armed, pressing the panic button on the keyless entry system transmitter causes the theft alarm horn to sound for about 180 seconds in an attempt to prevent theft. The alarm is turned off by pressing any switch on the transmitter.

ARMING THE SYSTEM
After the following procedure have been completed, the THEFT-ALARM indicator light illuminates for about 20 seconds, and when illumination stops, the system is armed.
1. Pull out ignition key from the key cylinder.
2. Open a door. (The other doors are locked.)
3. Lock the door within the key or the keyless locking method. (The central door locking system will then function to lock all doors.)

NOTE:
- The system is set regardless of whether the trunk lid is open or closed, and is armed as soon as the light goes out.
- While the timer is functioning (approximately 20 seconds), it is not reset even is the trunk lid is opened and closed.

DISARMING THE SYSTEM
The system will be disarmed:
1. If the key is used to unlock a door.
2. If the system is armed while the driver is still in the vehicle, the system can be disarmed by inserting the ignition key and turning t to the ACC or ON position.
3. If the door is unlocked while closing the door or the door is ajar.
4. If the door is unfastened while the THEFT- ALARM indicator light illuminates.
5. If, after the keyless warning is set, the door on the driver's side or passenger's side is locked but not completely closed (door-ajar)

ACTIVATING THE ALARM
1. If an attempt is made to open a door, the trunk lid, without using the key, while the system is armed, the horn will sound intermittently and the headlights (high-beam) will flash on and off for approximately three minutes.
2. If a further attempt at forcible entry is made after the first three-minute alarm has finished, the three-minute alarm will be activated again.

DEACTIVATING THE ALARM
1. To deactivate the alarm, insert the key into the door's key cylinder and turn the key.
2. The alarm is deactivate and the systems disarmed when the trunk lid is unlocked with the key.