Immobilizer System

WARNING: This page is about a different car, the 1997 Cadillac Catera. However, it is still accessible from the selected car via links, so may be relevant.

The "immobilizer" system is standard equipment on this vehicle. It is designed to prevent vehicle theft by interrupting fuel injectors and ignition feeds if proper transponder input is not recognized from the ignition key. The immobilizer system will allow the vehicle to start for a very short period regardless of the ignition key transponder's identification code. When a key with an incorrect code is used, engine control functions are interrupted after a maximum of one and a half seconds after the ignition is turned on. The system components include the ignition key, theft deterrent module with integrated antenna, transponder, Electronic Brake and Traction Control Module (EBTCM) and Power Control Module (PCM).

The transponder, installed in the key head, emits an identification code. This code is read by theft deterrent module mounted to the steering column. When this signal is introduced to the magnetic field generated by the coils of the theft deterrent module, a voltage is created and sent to the PCM. The PCM then compares this value to a value stored in its memory, and determines whether or not allow continued engine operation. The transponder does not require battery power, and should never require replacement under normal usage. The transponder and key are serviced as an assembly. Once a key has been replaced, the system musty be reprogrammed.