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 driveway theft. Passive means that it does not require any unique activity to operate the system.

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 which is one of many combinations.

Each encoded ignition key must be programmed into the vehicle's powertrain control module (PCM) before the key 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 is necessary.

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

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 does not start.

The PATS uses a visual theft indicator located in the instrument cluster. The indicator proves out for 3 seconds when the ignition switch is turned to RUN or START under normal operation. If there is a PATS problem, this indicator either flashes rapidly or glows steadily when the ignition switch is turned to RUN or START. The PATS system also flashes the theft indicator every 2 seconds at ignition OFF to act as a visual deterrent.

The PATS disables the vehicle from starting if there is a:
- damaged encoded ignition key
- unprogrammed key
- non-encoded key (key has no electronics)
- damaged wiring
- damaged transceiver
- damaged PCM