Without Intelligent Access (IA)

Anti-Theft - Without Intelligent Access (IA)

Principles of Operation

Passive Anti-Theft System (PATS) Operation

The Passive Anti-Theft System (PATS) is controlled by the Instrument Panel Cluster (IPC). There are two main checks that PATS performs before allowing the engine to start. If either of these checks fail, PATS does not allow the engine to start and the anti-theft indicator in the IPC flashes rapidly. These two checks are the IPC verifying the PCM ID to make sure it matches the PCM ID stored in memory and to verify that a programmed key was used to turn the ignition to the RUN or START position.

The first check is initiated when the ignition is turned to the RUN or START position. Once the IPC determines the ignition has been turned to the RUN or START position, it generates a challenge message. It sends this challenge message to the PATS transceiver on the transmit (TX) circuit. The transceiver in turn reads the key and generates a response message that is sent back to the IPC on the receive (RX) circuit. The engine does not start if the message received from the transceiver does not match a key stored in the IPC memory.

Once the IPC determines a programmed key was used to turn the ignition to RUN or START, the IPC sends the PCM a challenge message over the High Speed Controller Area Network (HS-CAN). When the PCM receives the challenge message, it generates a response and sends it back to the IPC. The engine does not start if the response from the PCM does not match the response in the IPC memory.

If both the key verification and PCM ID pass, PATS is enabled the engine is allowed to start. PATS cannot disable an engine that has already been started.

Spare Key Programming

The customer spare key programming allows spare keys to be programmed (up to a maximum of 8) to the IPC without having to use a scan tool. Two programmed keys are required to carry out the procedure. Refer to Key Programming - Program a Key Using Two Programmed Keys Using Two Programmed Keys for the customer spare key programming procedure.

Passive Anti-Theft System (PATS) PIDs

The Passive Anti-Theft System (PATS) PIDS are a useful tool when diagnosing a PATS concerns.