The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent system is provided in order to prevent the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key allows the lock cylinder to rotate. The cylinder rotation produces an analog voltage code in the Passlock™ sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a serial data message is sent from the BCM to the powertrain control module (PCM). The message enables the fuel injector operation.

The design of the Passlock™ system is to prevent vehicle theft by disabling the engine unless the ignition lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the Passkey system. However, the Passlock™ system eliminates the need for any key mounted components. The components of the Passlock™ system are as follows:

The ignition lock cylinder is located at the upper right side of the steering column. The Passlock™ sensor is in the steering column. The Passlock™ sensor is separate from the key and lock cylinder. The key and the lock cylinder work together in order to determine if the proper ignition key was used to start the vehicle.

In the event of an open serial data line between the body control module (BCM) and the powertrain control module (PCM), the vehicle will become fail-enabled if the PCM has already received the password from the BCM for that ignition cycle. In this event, the following conditions occur:

If a failure in the serial data line occurs before the ignition cycle, when the PCM is not fail-enabled, the following conditions occur:

The lock cylinder and the visible key insert portion of the ignition switch are located at the upper right side of the steering column. The electrical switching portion of the assembly is separate from the key and lock cylinder. The electrical switch portion is hidden inside the steering column. The electrical switch portion and the key and lock cylinder synchronize and work in conjunction through the action of the mechanical assembly between the two parts.

The Passlock™ sensor is inside the ignition cylinder lock housing. The Passlock™ sensor contains two hall effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. Placing the tamper sensor above the security sensor enables the tamper sensor to engage first if an intruder attempts to bypass the Passlock™ sensor by placing a large magnet around that area of the steering column. Passlock™ equipped vehicles have a selection of ten different security resistors ranging from 0.5K ohms up to 13.6K ohms. Installing one of the security resistors inside the Passlock™ sensor will generate a unique Passlock™ code.

The body control module (BCM) contains the theft deterrent system logic. The BCM reads the Passlock™ data from the Passlock™ sensor. If the Passlock™ data is correct, the BCM will pass theft. The BCM will then transmit the fuel continue password to the PCM.

During tamper mode the vehicle may start momentarily, then stall. If the BCM receives incorrect Passlock™ data, the VTD will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors for 10 minutes. The SECURITY indicator will flash while the VTD is in the tamper mode.

If the Passlock™ sensor sends a correct password to the BCM when the ignition is in the ON position, the BCM will send a fuel enable signal to the PCM. This fuel enable signal will allow proper operation of the fuel injectors and vehicle start.

The SECURITY indicator appears on the instrument cluster and is designed to report security system status. If the SECURITY indicator flashes or if the SECURITY indicator illuminates continuously during vehicle operation, refer to the system diagnosis.

The powertrain control module (PCM) communicates with the body control module (BCM) over the serial data line. When the BCM receives an incorrect VTD password from the Passlock™ sensor, it will send a serial data password to the PCM in order to disable the fuel injection system. If the BCM receives the expected voltage from the Passlock™ sensor, the BCM sends a serial data password to the PCM in order to enable the fuel injection system. The PCM then allows the vehicle to start correctly. If the PCM does not receive the expected message from the BCM, the vehicle will start and then stalls due to fuel lockout.

The Passlock™ system has a lockout cycle of approximately 10 minutes. Once the vehicle is in the lockout cycle, the vehicle remains in the lockout cycle for 10 minutes regardless of ignition position.

The Passlock™ system uses the lockout cycle in order to synchronize all of the Passlock™ components when any Passlock™ related part is changed. The Passlock™ system requires 3 consecutive lockout cycles in order to complete the 30 minute learn procedure for a changed component.

The design of the Passlock™ system is to prevent theft even if the various theft deterrent parts are changed. The parts that can no longer be replaced without the possibility of going into a tamper mode are:

If you replace any of these parts the vehicle may start and stall for 10 minutes. This is the long tamper mode. If this occurs, the system must go through a long tamper mode cycle. During this time the SECURITY telltale will be flashing for the full 10 minutes and the DTC B3031 will be set. The BCM and the PCM requires the full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the RUN position until the SECURITY indicator stops flashing. You will need to repeat the cycle if the ignition switch does not remain in the RUN position. When replacing any of the above parts it is recommended to perform the Programming Theft Deterrent System Components procedure.