Engine Immobilizer Systems: Description
NOTE:
Before performing service procedures, check for any related Technical Service Bulletins (TSBs).
WARNING:
Vehicle is equipped with air bag supplement restraint system. Before attempting ANY repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article.
NOTE:
Models equipped with engine immobilizer system may be identified by looking at the ignition key. On models equipped with engine immobilizer system, the top of the ignition key is thicker than a standard ignition key, as a transponder chip is incorporated into the top of the ignition key. If a problem exists in the engine immobilizer system, a Diagnostic Trouble Code (DTC) may be stored in the Engine Control Module (ECM), but the Malfunction Indicator Light (MIL) will not come on. MIL is displayed as an engine icon just below the tachometer on instrument cluster. MIL may also be referred to as CHECK ENGINE light.
Engine immobilizer system is a theft deterrent system that disables engine from starting by not allowing fuel injector operation and ignition system operation unless ignition key identification code matches identification code stored in the Engine Control Module (ECM). Engine immobilizer system consists of ECM, ignition key with built-in transponder chip, transponder key coil, transponder key amplifier and key unlock warning switch. See Fig 1. Key unlock warning switch may also be referred to as unlock warning switch.