he passive anti-theft system (PATS) also contains the following components:
l Theft indicator.
l Encoded ignition key.
l Passive anti-theft transceiver module.
l Hybrid electronic cluster (HEC).
l Powertrain control module.
l J1850 communication network.
l Lighting control module (LCM).
The passive anti-theft system (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. This information can be found in customer literature such as the Owner's Manual.
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 out of over 72 million billion combinations.
Each encoded ignition key must be programmed into a vehicle's hybrid electronic cluster (HEC) before it can be used to start the engine. There are special diagnostic service procedures outlined in the workshop manual 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 electronic module. During each vehicle start sequence, the transceiver module reads the encoded ignition key identification code and sends the data to the HEC.
The control functions are contained in the HEC. This module performs all of the PATS functions, such as receiving the identification code from the encoded ignition key and controlling engine enable. The HEC initiates the key interrogation sequence when the vehicle ignition switch is turned to RUN or START.
PATS uses the powertrain control module (PCM) to enable or disable the engine. The HEC communicates with PCM over the J1850 network in order to enable engine operation. The HEC and the PCM use sophisticated messages in order to prevent a theft. The HEC communicates with the lighting control module (LCM), which controls the theft indicator.The HEC 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 shared PCM ID is remembered even if the battery is disconnected. The HEC also stores the vehicle's key identification code even if the battery is disconnected. There are special diagnostic workshop procedures outlined in this service manual that may be performed if either the HEC or the PCM needs replacement.
All elements of 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.
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 indictor will either flash rapidly or glow steadily (more than three seconds) when the ignition switch is turned to RUN or START. PATS also "blips" the theft indicator every two seconds at ignition OFF to act as a visual theft deterrent.
PATS differs from the perimeter anti-theft system in that 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.
