The 2002 Honda Civic is equipped with an immobilizer system that will disable the vehicle unless the prior ignition key is used. The system consists of a transponder located in the ignition key, an immobilizer control unit-receiver, an indicator light and the ECM (engine control module). When the key is inserted in the ignition switch and turned to the ON (II) position, the immobilizer control unit-receiver sends power to the transponder in the ignition key. The transponder then sends a coded signal back to the immobilizer control unit-receiver which then sends a coded signal to the ECM.
The following schematic shows details of 2002 Honda Civic Immobilizer System Circuit Diagram.