PASS-Key II System

PASS-Key II SYSTEM CIRCUIT OPERATION

The Personal Automotive Security System (PASS-Key II) is a theft deterrent system which prevents the vehicle from starting if the Ignition Key "Resistance Code" is not recognized by the Theft Deterrent Module. If the Resistance Code is not recognized, the Engine is prevented from starting in two ways: battery voltage from the Ignition Switch to the starter is disabled by a Theft Deterrent Relay and fuel to the fuel injectors is stopped without the presence of a fuel enable signal. Resistor sensing contacts are located in the Ignition Key Lock Cylinder. These contact the Key Resistor Pellet on the key when it is inserted. When the lock is rotated, Ignition voltage is applied to the Theft Deterrent Module and pellet resistance is read at this time. The Pellet resistance is read across terminals "B7" and "B8" which is then compared against the resistance value stored in the Module. If the Key Resistance Pellet is the proper resistance, terminal "A4" is grounded, energizing the Theft Deterrent Relay. At the same time, a signal is applied at terminal "A3" to enable the Powertrain Control Module (PCM). When this signal is received by the PCM, it allows fuel injector pulses to begin. If the Key Resistor Pellet is the wrong value, the Theft Deterrent Module will shut down for 3 minutes +/- 18 seconds. During this interval, there will be no output at terminals "A3" or "A4" and the "SECURITY" Indicator will illuminate. The Ignition Switch input is ignored during this shut down period. For this reason, the timer will run and the "SECURITY" Indicator will remain illuminated with Ignition on or off. Once the timer has completed its 3 minute +/- 18 second shut down, the next time Ignition is cycled from off to on, the Theft Deterrent Module timer is reset. A key having the correct code can then be used to start the Engine.