Passive Anti-Theft System

Anti-Theft, Passive System Operation

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 four quadrillion combinations.

Each encoded ignition key must be programmed into a vehicle's PATS module before it can be used to start the engine. There are special diagnostic service procedures outlined in this 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 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 performs 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 J1850 standard corporate protocal (SCP) network in order to enable engine operation. The PATS module and the PCM use sophisticated messages in order to deter a theft. PATS 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 PATS shared security ID is remembered even if the battery is disconnected. The PATS module also stores the vehicle's key identification code even if the battery is disconnected. There are special diagnostic service procedures that may be performed if either the PATS module or the PCM needs replacement.

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

The PATS differs from the perimeter anti-theft system 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.

Components

The passive anti-theft system (PATS) contains the following components:
^ PATS module
^ THEFT indicator in instrument cluster
^ transceiver electronics
^ Powertrain Control Module (PCM)
^ encoded ignition key
^ J1850 Standard Corporate Protocal (SCP) communications network
^ Data Link Connector (DLC)

Vehicle Disabling

The passive anti-theft system (PATS) will be activated and will disable the vehicle from starting if any of the following conditions exist:
^ damaged encoded key
^ unprogrammed key
^ non-encoded key (key has no electronics)
^ wiring concern
^ transceiver concern
^ PATS module concern
^ J1850 standard corporate protocal Communications-Network concern
^ powertrain control module (PCM) concern

Vehicle Enabling

For normal anti-theft system proveout and engine enabling to occur, the THEFT indicator must proveout as follows:
^ Normal operating proveout on theft indicator is two seconds ON then OFF after the ignition switch has been turned from OFF to RUN/START position. This vehicle should start.
^ If normal two-second proveout occurs and engine cranks for more than one second after ignition switch is turned to START position but fails to start, the concern is not in the passive anti-theft system (PATS).