Circuit Description

Immobilizer System

How the Circuit Works

The immobilizer system is designed to prevent the vehicle from being started without the owner's ignition key. If an attempt is made to start the vehicle with any other key, the immobilizer system disables it from starting.

If the proper ignition key is used, the immobilizer-keyless control unit sends a coded signal to the ECM/PCM and illuminates the immobilizer system indicator LED for 2 seconds. The coded signal informs the ECM/PCM that the proper ignition key is being used. The ECM/PCM grounds the Fuel Pump Relay, energizing it to provide power to the fuel pump. Following the first 2 seconds after the ignition switch is turned to ON (II) with the proper ignition key, the immobilizer system indicator LED turns off, and the engine will run under normal operating conditions.

Power Supply

Battery voltage is supplied at all times through fuse 15 (in the under-hood fuse/relay box) to the immobilizer-keyless control unit and the gauge control module. With the ignition switch in ON (II) or START (Ill), the immobilizer-keyless control unit and the ECM/PCM receive battery voltage through fuse 9 (in the driver's under-dash fuse/relay box).

Normal operation

- When the ignition switch is turned ON (II) and a programmed immobilizer code is identified, the immobilizer indicator quickly flashes once.
- The immobilizer system will allow the engine to start normally.
- When the ignition switch is turned OFF (0), the immobilizer indicator does not come on. Please note that this is different from some previous systems.

Immobilizer system detects a problem

- When the ignition switch is turned ON (II), and a programmed immobilizer code is not identified, the immobilizer indicator quickly flashes once and then blinks continuously.
- The immobilizer system results will vary depending on how quickly the key is turned. If the key is turned quickly from the OFF (0) position to the START (III) position, the engine will start and run for approximately 1 second and shut off. If the key is turned to the ON (II) position, delayed there, and then turned to START (III) position, the starter will turn the motor over, but it will not start.
- When the ignition switch is turned OFF (0), the immobilizer indicator does not illuminate. Please note that this is different from previous systems.