Passive Anti-Theft System

The Passive Anti-Theft System (PATS) contains the following components:
^ Theft indicator.
^ Encoded ignition key.
^ Transceiver module.
^ Virtual Image Instrument Cluster (VIC).
^ Powertrain Control Module (PCM).
^ J1850 communication network.
^ Lighting Control Module (LCM).

The PATS uses radio frequency identification technology to deter a driveaway theft. Passive means that it does not require any activity from the user. This system is known as Securilock in North America, Safeguard in the U.K., and PATS in Continental Europe.

The PATS uses a specially encoded ignition key. Each encoded ignition key contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code, with over four quadrillion combinations.

Each encoded ignition key must be programmed into the vehicle's VIC before it can be used to start the engine. There are special diagnostic procedures that must be performed if the encoded ignition keys need to be replaced.

The encoded key is larger than a traditional ignition key. The key does not require batteries and should last the life of the vehicle.

The transceiver module communicates with the encoded ignition key. This module is located behind the steering column shroud, and contains an antenna connected to a small electronics module. During each vehicle start sequence, the transceiver module reads the encoded ignition key identification code and sends the data to the VIC.

The control functions are contained in the VIC. This module performs all of the PATS functions such as receiving the identification code from the encoded ignition key and controlling engine enable. The VIC initiates the key interrogation sequence when the vehicle ignition switch is turned to RUN or START.

The PATS uses the PCM to enable or disable the engine. The VIC communicates with the PCM over the J1850 network in order to enable engine operation. The VIC and the PCM use sophisticated messages in order to prevent a theft. The VIC communicates with the LCM, which controls the theft indicator. The VIC and the PCM share security data when first installed together that makes them a matched pair. After this security data sharing, these modules will not function in other vehicles. The VIC shared security ID is remembered even if the battery is disconnected. The VIC also stores the vehicle's key identification code even if the battery is disconnected. There are special diagnostic procedures that may be performed if either the VIC or the PCM needs replacement.

All elements of the PATS must be functional before the engine is allowed to start. If any of the components are not working properly, the vehicle will not start.

The PATS uses a visual theft indicator. This indicator will prove out for three seconds when the ignition switch is turned to RUN or START under normal operation. If there is a PATS problem, this indicator will either flash rapidly or glow steadily (for more than three seconds) when the ignition switch is turned to RUN or START. The PATS also "blips" the theft indicator every two seconds at ignition OFF to act as a visual theft deterrent.

PATS differs from perimeter anti-theft systems in that the PATS enables and disables the engine from starting. If equipped, the perimeter anti-theft system protects the perimeter of the vehicle (doors, hood and trunk) and sounds an alarm.