The Passlock™ System is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. If starting is attempted without authorization from the Passlock™ System, the powertrain control module (PCM) will disable engine starting. Start disable may be in the form of fuel disable or starter disable, depending on engine application.

The components of the Passlock™ System are as follows:

The ignition lock cylinder fits inside the ignition lock cylinder case and operates the ignition switch when turned by a key with the proper mechanical cut. When the ignition key is used to turn the ignition lock cylinder to crank, start, a magnet on the lock cylinder passes close to the Passlock™ sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock™ sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle.

If a magnet from outside of the ignition lock cylinder case is used to attempt to steal the vehicle, the tamper hall effect sensor will be activated. This completes a circuit from the security sensor signal circuit through a tamper resistor to the security sensor low reference circuit bypassing the security resistor. If the ignition switch is forced to rotate without the correct key, or if the ignition lock cylinder is removed by force, the Passlock™ sensor will be damaged and will not operate.

The ignition switch contains the wiring and electrical switching portion of the column mounted ignition assembly. The ignition switch includes wiring pigtails which connect it to the base of column connector, the Passlock™ sensor on the ignition lock cylinder case, and other components. The wiring for the Passlock™ sensor is unaffected by ignition switch position. The electrical switch portion is operated by the key and lock cylinder when they are rotated within the ignition lock cylinder case. The ignition switch operates the crank relay regardless of the status of the Passlock™ System.

The body control module (BCM) contains the logic of the Theft Deterrent System. The BCM provides the battery positive voltage to operate the Passlock™ sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock™ sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the powertrain control module (PCM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.

The powertrain control module (PCM) contains the remainder of the logic of the Theft Deterrent System. If a class 2 message containing a valid password is received from the body control module (BCM), the PCM will continue to allow the fuel injectors to operate. The PCM will allow the fuel injectors to operate until it decides there is no valid password coming from the BCM. If the PCM does not receive a class 2 message, or receives a class 2 message with an incorrect password, the engine will crank and will not run or will start and stall immediately.

The instrument panel cluster (IPC) illuminates the theft deterrent indicator as determined by the theft deterrent system. The IPC receives a class 2 message from the BCM requesting illumination.

When it receives a password which is incorrect or a password which indicates tamper and the powertrain control module (PCM) disables the fuel injectors, the fuel injectors remain disabled for 10 minutes even if the ignition switch is turned from the RUN position to the OFF position.

The following components contain codes or passwords, or must learn codes or passwords for the Passlock™ System to allow the vehicle to start:

If any of these parts are replaced, a learn procedure must be performed. Refer to Programming Theft Deterrent System Components. If parts are replaced and a learn procedure is not performed, the engine will crank and will not run or will start and stall immediately.

The immobilizer - export passkey III+ system functions are provided by the theft deterrent module (TDM). When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the TDM. The TDM then compares this value to a value stored in memory, learned key code. If the value is correct the TDM sends a random generated number to the transponder, this is called a challenge. Both the transponder and the TDM perform a calculation on the challenge, if the calculations match the TDM sends the fuel enable password via the serial data circuit to the powertrain control module (PCM). If either the transponders unique value or the calculation to the challenge is incorrect the TDM will send the fuel disable password to the PCM via the serial data circuit. The components of the immobilizer passkey III+ system are as follows:

Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent module (TDM) which is located within the steering column. Vehicles with instrument panel mounted ignition switches have exciter modules separate from the TDM with the vehicle wiring harness connecting the two. The TDM for vehicles with instrument panel mounted ignition switches is located within the instrument panel. The TDM can learn up to ten keys (transponder values).

The TDM uses the following inputs, battery voltage, ignition switched voltage and ground circuit. The TDM uses the following outputs, password exchange with the PCM, fuel enable/disable via the serial data circuit.

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the TDM. The TDM then compares this value to a value stored in memory, learned key code. If the value is correct the TDM sends a random generated number to the transponder, this is called a challenge. Both the transponder and the TDM perform a calculation on the challenge. The TDM then performs one of the following functions:

The powertrain control module (PCM) verifies that the password received from the theft deterrent module (TDM) via the serial data circuit is correct. The PCM can learn only one fuel continue password. If the fuel continue password is correct, the PCM enables the starting and fuel delivery systems.

The PCM disables the starting and fuel delivery systems if any of the following conditions occur:

The ignition key on vehicles equipped with the passkey III+ system is a typical looking ignition key with a transponder located in the plastic end of the key. The transponder value is fixed and unable to be changed. The theft system uses the ignition key transponder value to determine if a valid ignition key is being used to start the vehicle. There are approximately three trillion possible transponder values. There are no visible electrical contacts. The keys may be identified by the letters PK3+ stamped into the steel shank of the key. The theft systems use the following types of ignition keys:

Master Keys

Master keys have a black plastic end are for full access operation of the vehicle. Master keys may perform the following functions:

The ignition lock cylinder performs all of the functions of a lock cylinder on a non PK3+ equipped vehicle. The ignition lock cylinder for vehicles with PK3+ may be located on the steering column or on the instrument panel. In either location the exciter coils surround the ignition lock cylinder such that they are very close to the head of the key which contains the transponder pellet.

If an ignition lock cylinder is replaced, the PK3+ keys must match the mechanical coding of the new lock cylinder. When replacing an ignition lock cylinder, and new PK3+ keys are required, refer to Theft Deterrent Control Module Programming and Setup.

The theft deterrent control module can command the instrument cluster to illuminate the SECURITY indicator only when the ignition key is in the ON position. If the powertrain control module (PCM) loses communication with the theft deterrent control module, the instrument cluster will also detect the loss of communication and will illuminate the SECURITY indicator. The SECURITY indicator can indicate both malfunctions, Indicator on steady and tamper, Indicator flashing. A flashing indicator indicates unauthorized operation. Under the following conditions the SECURITY indicator may be commanded to illuminate.

SECURITY Indicator Illuminates when Engine is Running

If the theft deterrent control module is unable to measure the ignition key transponder value or the PCM loses communication with the theft deterrent control module while the engine is running, the indicator will be illuminated.

SECURITY Indicator Illuminated and Engine Does Not Start

If the theft deterrent control module was unable to measure the ignition key transponder value or the PCM has detected a problem with the theft deterrent system. The theft system is in Learn Mode. Refer to Theft Deterrent Control Module Programming and Setup.

SECURITY Indicator Flashes and Engine Does Not Start

The theft deterrent control module has measured an incorrect transponder value, the calculation to the challenge is incorrect or the PCM has lost communication with the theft deterrent control module, The theft system considers this a tamper condition. The theft indicator will flash.