Principles of Operation

PASSIVE ANTI-THEFT SYSTEM (PATS) - PRINCIPLES OF OPERATION

The passive anti-theft system (PATS) uses radio frequency identification technology to deter a drive-away theft. Passive means that it does not require any activity from the user. This system is known as SecuriLock(R) in North America, Safeguard(R) in the U.K., and PATS in continental Europe. This information can be found in owner literature.

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 encrypted identification code out of over 18 billion, billion combinations.

Each encoded ignition key must be programmed into the vehicle PATS module before it can be used to start the engine. There are special diagnostic repair procedures that must be carried out if the encoded ignition keys need to be replaced.

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 PATS module.

The control functions are contained in the PATS module. This module carries out all of the PATS functions, such as receiving the identification code from the encoded ignition key and controlling engine enable. The PATS module 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 PATS module communicates with the PCM over the standard corporate protocol (SCP) communication network in order to enable engine operation. The PATS module and the PCM use sophisticated messages in order to prevent theft. The PATS and PCM share security data when first installed together, making them a matched pair. After this security data sharing, these modules will not function in other vehicles. The PCM shared security ID is remembered even if the battery is disconnected. The PATS module also stores the vehicle key identification code, even if the battery is disconnected. There are special diagnostic repair procedures that may be carried out if either a new PATS module or the PCM needs to be installed.

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

PATS uses a 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 concern, this indicator will either flash rapidly or glow steadily when the ignition is turned to RUN or START. PATS also flashes the theft indicator every two seconds at ignition OFF to act as a visual theft deterrent.

The PATS is not compatible with aftermarket remote starting systems, which allow the vehicle to be started from outside the vehicle. These systems may reduce the vehicle security level, and also may cause no-start issues. Remote start systems must be removed before investigation of PATS-related no start issues.

The passive vehicle protection system will be activated and will disable the vehicle from starting if there is a:
- damaged encoded key.
- unprogrammed key.
- non-encoded key (key has no electronics).
- wiring concern.
- transceiver concern.
- PCM concern.
- SCP network concern between the PATS module and the PCM.
- PATS module concern.