Components

The passive anti-theft system contains the following components:
^ Passive Anti-theft System (PATS) control module
^ THEFT indicator in instrument cluster
^ Transceiver electronics
^ Powertrain Control Module (PCM)
^ Encoded ignition key
^ Anti-theft alarm control mounting bracket
^ J-1850 communications network
^ Data Link Connector (DLC)

The PATS components function as follows:
^ THEFT Indicator
- The anti-theft vehicle protection system utilizes the same THEFT indicator (located in the instrument cluster) that the anti-theft alarm system (if equipped) uses.
- The indicator provides system proveout and operating status to the customer or service technician.
- The anti-theft alarm system uses the THEFT indicator when the ignition switch is turned OFF, and the passive anti-theft vehicle protection system uses the THEFT indicator when the ignition switch is turned to RUN/START position.
- When the ignition switch is turned to RUN/START position, the PATS will activate the THEFT indicator signal ON for two seconds, then OFF to indicate Keycode Received/Vehicle Enabled (Programmed key)

Any other THEFT indicator illumination (while ignition key is in RUN/START) indicates a PATS concern:
^ If THEFT indicator is ON two seconds, then OFF one second, then ON continuously, this indicates key code received/vehicle disabled (assembly plant use only, less than two keys programmed).
^ If THEFT indicator is ON two seconds, then flashes for one minute, then flashes Fault Code 16 ten times, this indicates key code received/vehicle enabled or disabled (no PCM verification).
^ If vehicle starts, PCM is not communicating with PATS control module.
^ If vehicle does not start, the J-1850 Communication Network may need service.
^ If THEFT indicator flashes for one minute, this indicates no key code received. Possible causes include:
^ damaged key.
^ non-encoded key.
^ wiring concern.
^ PATS module.
^ If THEFT indicator flashes for 15 minutes, this indicates key code received/vehicle disabled (key not programmed).

^ Encoded Ignition Key
- When the vehicle ignition switch is placed into either RUN or START, the PATS control module requests the ignition key ID code.
- The PATS control module requests the ignition key ID code by supplying both power and the carrier signal to the transceiver to energize the ignition key.
- After the energize period, the key transmits its ID code to the transceiver module.
- This ignition key is much larger in size due to the electronics that are located in the head of the ignition key.

^ Transceiver
- Interfaces the PATS control module to the encoded ignition key.
- Sends power to the encoded key and receives the ignition key data signal.
- In turn, the transceiver sends the key code to the PATS control module which determines if the key being used is a properly coded key.

^ PATS Control Module
- The control module contains circuitry to interface the vehicle electrical system, the transceiver module, the vehicle J-1850 communications network and the J-1850 THEFT indicator located in the instrument cluster.
- The control module uses a microprocessor to control the system functions.
- The control module microprocessor stores the ignition key codes in Non-Volatile Random Access Memory (NVRAM) memory.
- The control module can be diagnosed through the data link connector.

^ Powertrain Control Module
- The PATS module to enable or disable the engine.
- The J-1850 communications network is used to send and receive messages to and from the PCM.
- At each engine start sequence, the PCM allows fuel and spark until the engine is running.
- Within one second after engine start, the PCM must receive an enable signal from the PATS control module or the engine is disabled.
- If the PATS control module recognizes a stored ignition key code and if there is no J-1850 communication network concern preventing the PCM recognizing the start enable signal from the PATS module, the engine will start and run.