Antitheft and Alarm Systems: Description and Operation

DESCRIPTION
PASS-Key@II is a theft deterrent function which prevents the vehicle from starting if the Ignition Key "Resistance Code" is not recognized by the PASS-Key@II Decoder Function in the Central Control Module (CCM).

OPERATION
The vehicle is prevented, from starting in two ways: battery voltage from the Ignition Switch to the starter is disabled by a Starter Enable Relay and fuel to the fuel injectors is controlled by the presence of a fuel enable signal

When the Ignition Key is inserted into the lock cylinder, the CCM compares the resistance value of the key resistor pellets to the value stored in memory of the CCM. If the values match, the CCM sends a ground signal to energize the Starter Enable Relay at the same time the CCM sends a modulated "Fuel Enable" signal to the Electronic Control Module (ECM). When the ECM receives this signal, fuel delivery begins.

The CCM sends a control signal to illuminate a "PASS KEY FAULT" Indicator on the Instrument Cluster during start up as a "bulb check" and also when a fault is detected in the PASS-Key@II System.