General Description

By disabling the engine unless the Passlock(TM) lock cylinder properly rotates with the engagement of the correct ignition key, the Passlock(TM) system prevents theft of the vehicle. This system is similar to the PASS-Key(R) system. However, Passlock(TM) eliminates the need for a key-mounted resistor pellet. This system includes the following components:
^ The Passlock(TM) lock cylinder
^ The ignition switch
^ The Passlock(TM) sensor
^ The Passlock(TM) module
^ The SECURITY indicator
^ The vehicle control module (VCM) The powertrain control module is equivalent reference to the VCM throughout the theft deterrent system procedures.

Passlock(TM) Lock Cylinder
The properly-cut key inserted in the Passlock(TM) lock cylinder turns the lock cylinder clockwise. This action rotates a magnet beyond a stationary hall effect sensor and creates Passlock(TM) cylinder data, which the Passlock(TM)/electronic variable orifice (EVO) receives.

Place the Passlock(TM) lock cylinder in the START position in order to remove the lock cylinder for replacement.

Ignition Switch
The lock cylinder and the key insert of the lock cylinder, which is the visible portion of the part, are on the upper right side of the steering column. The electrical switching portion of the assembly is separate from the key and the lock cylinder. The steering column conceals the electrical switching portion. However, both the visible portion and the hidden portion of the ignition switch work in conjunction through the mechanical assembly between the components.

Passlock(TM) Sensor
The Passlock(TM) sensor is inside the upper right side of the steering column. The Passlock(TM) sensor contains 2 hall effect sensors. A tamper hall effect sensor is atop a security hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. Placement atop the security hall effect sensor enables first engagement of the tamper hall effect sensor in the event that an intruder attempts bypassing the Passlock(TM) sensor by placing a large magnet in the area of the upper right side of the steering column. A 274 ohms tamper resistor is inside the Passlock(TM) sensor. C/K vehicles have a selection of 10 different resistors. The resistors range to 13 k ohms. The Passlock(TM) sensor may contain any one of the resistors in order to generate a unique Passlock(TM) code. All 10 combinations of the Passlock(TM) sensor have the same part number. However, you cannot simply replace the Passlock(TM) sensor and expect the proper operation of the system. Follow the replacement instructions specified in Steering Column Unit Repair.

Passlock(TM) Module
The Passlock(TM)/EVO module contains the theft deterrent system's logic. The Passlock(TM) module reads the Passlock(TM) data from the Passlock(TM) lock sensor. If the Passlock(TM) data is correct, the Passlock(TM) module issues a Pass Theft signal. The Passlock(TM) module then transmits the module's coded password to the VCM.

IMPORTANT: Note that during any Tamper Mode, the vehicle may start. However, the vehicle then quickly stalls. When the Passlock(TM) module receives the wrong Passlock(TM) data, the theft deterrent system immediately goes into the system's Tamper Mode, in which the vehicle's fuel injectors are locked-out for a period of 10 minutes as described above. The SECURITY indicator flashes when the theft deterrent system is in the Tamper Mode.

If the Passlock(TM) sensor sends a correct password to the Passlock(TM) module when the ignition switch turns to the ON position, the Passlock(TM) module sends a fuel enable signal to the VCM. The VCM does not disable the fuel injectors as a result of any Passlock(TM) module message for the remainder of that ignition cycle.

SECURITY Indicator
The SECURITY indicator is on the instrument cluster. If the SECURITY indicator flashes, or if the SECURITY indicator lights continuously during the vehicle operation, refer to A Diagnostic System Check - Theft Deterrent. Testing and Inspection