Circuit Description

How the Circuit Works

The immobilizer system is designed to prevent the car from being started without the owner's ignition key. If an attempt is made to start the car with any other key, the immobilizer system will not enable the car's fuel supply system.

The immobilizer system consists of the ignition key, immobilizer control unit-receiver, immobilizer system indicator, PGM-FI main relays, fuel pump, and the ECM.

Battery voltage is supplied at all times through fuse 25 (in the under-dash fuse/relay box) to the immobilizer control unit-receiver. With the ignition switch in ON (II), the immobilizer control unit-receiver and the ECM receive battery voltage through fuse 2 (in the under-dash fuse/relay box). The ignition key transponder examines the ignition key, then sends a coded signal back to the ECM through the immobilizer control unit-receiver. If the ignition key signal is correct, the ECM will enable the car's fuel supply system by grounding the PGM-FI main relay 2. The immobilizer system indicator flashes a code to indicate that a correct ignition key has been inserted. If the ignition key signal is not correct, the ECM will not ground the PGM-FI main relay 2 which will not enable the car's fuel supply system. The immobilizer system indicator then flashes a code to indicate that an incorrect ignition key has been inserted.