Alarm Module: Description and Operation

How the Immobilizer System 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 disable the car's fuel supply.

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

With the ignition switch in ON (II) or START (III), the immobilizer receiver unit and the ECM receive an "ignition on" signal through fuse 7 and the PGM-FI main relay. The ECM then sends power to the ignition key transponder through the immobilizer receiver unit. The transponder then sends a coded signal back to the ECM through the receiver. If the signal is correct, the ECM will enable the car's fuel supply system by grounding the fuel cut relay. The immobilizer system indicator then flashes a code to indicate that the correct key has been inserted. If the ignition key signal is not correct, the ECM will disable the car's fuel supply system by not grounding the fuel cut relay. The immobilizer system indicator then flashes a code to indicate that an incorrect key has been inserted.

Refer to the Body Electrical System for specific tests and troubleshooting procedures.