Principles of Operation (How Does It Work?)

The Passive Anti-Theft System (PATS) uses radio frequency identification technology to deter a driveway theft. Passive means that it does not require any activity from the user.

The PATS uses a specially encoded ignition key which contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code out of millions of combinations.

Each encoded ignition key must be programmed into the vehicle Powertrain Control Module (PCM) before it can be used to start the engine. There are special diagnostic repair procedures outlined in this manual that must be carried out if a new encoded ignition key needs to be installed.

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 data to the PCM.

The PCM, carries out all of the PATS functions, such as receiving the identification code from the encoded ignition key and controlling engine enable. The PCM initiates the key interrogation sequence when the vehicle ignition switch is turned to position II or III.

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 engine 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 position II or III under normal operation. If there is a PATS fault, this indicator will glow continuously when the ignition switch is turned to position II or III. The PATS system also flashes the theft indicator every two seconds at ignition position 0 to act as a visual deterrent.

The PATS will be activated and will prevent the engine from starting if there is:
^ A damaged encoded ignition key
^ A unprogrammed key
^ A non-encoded key (key has no electronics)
^ A damaged wiring
^ A damaged transceiver
^ A damaged PCM