Circuit Operation

There are two separate subsystems. The first is the PASS-Key (R) III vehicle anti-theft subsystem. The second is the Content Theft Deterrent (CTD) subsystem. Components common to both subsystems are the SECURITY telltale lamp and the Class 2 Data Link. Please note that the SECURITY light is not tested during the ignition switch bulb check.

Pass-Key (R) III
The PASS-Key (R) III system provides protection against unauthorized operation of the vehicle. It does not provide any visible or audible indication of illicit attempts to start the vehicle. Visible and audible alarms are done only by the Integral CTD. The PASS-Key (R) III system sends a unique fuel continue password to the Powertrain Control Module (PCM) via Class 2 Bus, if a valid key is used. This password is not sent if an invalid key is used. If the PCM does not receive this unique password, it disables the vehicle starter and cuts off the fuel supply. Also, if the PCM receives an invalid fuel continue password indicating a switched PASS-Key (R) module, it will not allow fuel continue or starter enable. The PASS-Key (R) III module continuously communicates with the PCM to ensure any change in current key status is detected.

Security Telltale (with Key In Ignition)
The SECURITY Telltale is controlled by the Remote Function Actuator (RFA) Module and has three possible states:
1. ON
2. FLASHING at a 1Hz rate
3. OFF

The SECURITY telltale ON state is evoked two ways:
1. PCM or PASS-Key (R) III Module is in the Learn Mode.
2. If:
^ Any Diagnostic Trouble Codes (DTC) is set or the PCM VTD Fail-Enable was true in the last Vehicle Security Status Message and
^ The PASS-Key (R) III Module or PCM is not in the Learn mode.

The FLASHING telltale state is enabled by a PCM Fuel Disable Timeout condition set in the last Vehicle Security Status Message received since ignition was turned ON.

The SECURITY telltale is in the OFF state at all other times.

Keys
The keys required for this system have a transponder located in the head of the key. Each key transponder has a unique code. Approximately three trillion codes are available (This coding is not visible).

The vehicle is supplied with two valet keys. The valet keys are mechanically and electrically different from the normal keys. The mechanical key cut of the valet key is the same as the standard key. The valet key is missing a groove on top which prevents entry into the vehicle rear storage compartment, I/P storage compartment or I/P valet Lockout Switch. Electrically, the valet key is identified by the PASS-Key (R) III controller module, and does not allow the valet key user to reprogram other keys into the vehicle.

Operation
The PASS-Key (R) III controller has the capability of learning up to 10 unique key codes. When a driver inserts a key into the ignition key cylinder, the transponder embedded in the head of the key is excited by a coil surrounding the key cylinder, and emits a modulated signal that contains the unique code of that key. The PASS-Key (R) III controller then verifies it is one of the learned keys for that vehicle. Once the key is verified, the controller sends a unique fuel continue password to the PCM. When the PCM receives the correct fuel continue password, it enables the starter enable relay and allows the vehicle to crank. This password is not the key code, but a preprogrammed code from the manufacturer. This password prevents a thief from switching the PASS-Key (R) III module in order to steal the car, and provides a second level of vehicle theft deterrence. The conventional mechanical code of the key is still used to unlock and release the steering wheel and transmission lever.

If the PASS-Key (R) III system detects an invalid key, or unauthorized driver, it does not transmit the required password to the PCM for fuel and starter enable. If the PCM receives an invalid fuel continue password, indicating a swapped PASS-Key (R) III module, it does not allow fuel or starter enable. PASS-Key (R) III does not have a shut down period unless someone attempts to reprogram a new electronically coded key which takes the PASS-Key (R) III system thirty minutes to learn. It relies on the volume of electrical key codes, or the thirty minute relearn period, to deter the common thief.

Once the vehicle is started, the PASS-Key (R) III system constantly monitors system integrity. Should an error arise (Diagnostic Trouble Code become active) during normal operation, the SECURITY indicator turns ON, signaling the driver that a fault has been detected in the system. The vehicle continues to operate despite the fault; however in this case, vehicle security may be compromised, and the system should be serviced.