The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent system prevents the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the ignition lock cylinder. 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 class 2 message is sent from the BCM to the powertrain control module (PCM). The message enables the fuel injectors and the crank relay.

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 a key mounted resistor pellet. The components of the Passlock™ system are as follows:

The Passlock™ sensor and ignition lock cylinder are one assembly. 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 class 2 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 (the engine is running). In this event, the following conditions occur:

If a failure in the class 2 serial data line occurs before the ignition cycle, when the PCM is not fail-enabled, the following conditions occur:

The electrical switching portion of the ignition lock cylinder assembly is separate from the key and lock cylinder. 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 components.

The Passlock™ sensor contains 2 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. The tamper hall effect sensor is physically placed on top of the security hall effect sensor. This arrangement enables the tamper hall effect 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. There is a tamper resistor inside the Passlock™ sensor in order to help prevent tamper to the system. Passlock™ equipped vehicles have a selection of 10 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. All 10 combinations of the Passlock™ sensor have the same part number.

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 send a class 2 message to the PCM to enable the fuel injectors and crank relay.

During the tamper mode the vehicle may start. The vehicle will then stall. If the BCM receives the wrong Passlock™ data, the VTD system will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors and crank relay 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 and crank relay enable signal to the PCM.

The SECURITY indicator appears on the message center inside the instrument cluster. If the SECURITY indicator flashes or if the SECURITY indicator lights continuously during vehicle operation, refer to the system diagnosis.

The powertrain control module (PCM) communicates with the body control module (BCM) over the class 2 serial data line. When the BCM determines an incorrect password, it sends a class 2 serial data password to the PCM in order to disable the crank relay and fuel injection system. If the BCM receives the expected voltage from the Passlock™ sensor, the BCM sends a class 2 serial data password to the PCM in order to enable the crank relay and fuel injection system. The PCM then allows the vehicle to start normally.

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, even if the ignition switch is turned from the ON position to the OFF position.

The Passlock™ system uses the lockout cycle in order to synchronize all of the Passlock™ components when any Passlock™ related part is replaced. 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 change. The parts that can no longer be changed without the possibility of going into a tamper mode are:

If you replace any of these parts the vehicle may not start 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 indicator will be flashing for the full 10 minutes and DTC B3031 will be set. The BCM and the PCM require the full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the ON position until the SECURITY indicator stops flashing. You will need to repeat the cycle if the ignition switch does not remain in the ON position. When replacing any of the above parts, perform the Programming Theft Deterrent System Components procedure.

The design of the Passlock™ system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the ignition lock cylinder. The Passlock™ sensor monitoring the position of the lock cylinder will relay the Passlock™ data to the body control module (BCM). The BCM will determine the validity of the Passlock™ data. The BCM will send a password to the powertrain control module (PCM). When the PCM receives the correct password the PCM allows the crank relay and fuel injectors to operate normally. The Passlock™ system requires the PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line. For an explanation of the class 2 serial data description and operation refer to Data Link Communications Description and Operation in Computer/Integrating Systems.