Passive Anti-Theft System (PATS) - without Intelligent Access (IA)

Passive Anti-Theft System (PATS) - without Intelligent Access (IA)

Overview

PATS (Passive Anti-Theft System) protects the vehicle from theft by preventing the engine from starting unless a programmed PATS (Passive Anti-Theft System) key is in the ignition. PATS (Passive Anti-Theft System) cannot disable an already running engine.

System Operation

System Diagram





Network Message Chart

Module Network Input Messages - PCM (Powertrain Control Module)





Module Network Input Messages - BCM (Body Control Module)






Passive Anti-Theft System

The PATS (Passive Anti-Theft System) is controlled by the BCM (Body Control Module). There are 2 main checks that PATS (Passive Anti-Theft System) performs before allowing the engine to start. If either of these checks fail, PATS (Passive Anti-Theft System) does not allow the engine to start and STARTING SYSTEM FAULT is displayed in the message center. These 2 checks are the BCM (Body Control Module) verifying the PCM (Powertrain Control Module) identification to make sure it matches the PCM (Powertrain Control Module) identification 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 by the BCM (Body Control Module) waking up the PCM (Powertrain Control Module) by supplying voltage on the wakeup control circuit. The BCM (Body Control Module) only activates the wakeup circuit 5 times. After that the wakeup circuit remains off until the ignition is cycled to RUN. The BCM (Body Control Module) activates the wakeup control circuit when:
- the driver door is opened.
- a remote start request is received (if equipped with factory remote start).
- the brake pedal is pressed.
- a key is inserted into the ignition.
- or when the ignition is in the RUN or START position.

Once the PCM (Powertrain Control Module) is awake, the BCM (Body Control Module) sends the PCM (Powertrain Control Module) a challenge message over the HS-CAN (High Speed Controller Area Network). When the PCM (Powertrain Control Module) receives the challenge message, it generates a response and sends it back to the BCM (Body Control Module). If the response from the PCM (Powertrain Control Module) does not match the response in the BCM (Body Control Module) memory, this first check fails and the engine will not start.

Once the PCM (Powertrain Control Module) identification has been verified, PATS (Passive Anti-Theft System) performs the second check to make sure a programmed key is in the ignition. When the BCM (Body Control Module) determines the ignition has been turned to the RUN or START position, it generates a challenge message. It sends the challenge message to the PATS (Passive Anti-Theft System) transceiver on the transmit (TX) circuit. The transceiver in turn reads the key and generates a response message that is sent back to the BCM (Body Control Module) on the receive (RX) circuit. If the message received from the transceiver does not match a key stored in the BCM (Body Control Module) memory, the engine will not start.

If both the PCM (Powertrain Control Module) identification and key verification pass, PATS (Passive Anti-Theft System) is enabled and allows the engine to start. PATS (Passive Anti-Theft System) cannot disable or stall an engine that has already been started.

PATS (Passive Anti-Theft System) PIDs (Parameter Identifications)

In conjunction with DTCs (Diagnostic Trouble Codes), the PATS (Passive Anti-Theft System) PIDs (Parameter Identifications) are a useful tool when diagnosing PATS (Passive Anti-Theft System) concerns.

Module PID Chart






Unlimited Key Mode

PATS (Passive Anti-Theft System) contains a feature called unlimited key mode. This feature allows a customer to program more than 8 keys to their vehicle if they request it. Each vehicle in unlimited key mode is set up with a special unlimited transponder security key code. This allows all of the customer vehicles to share the same mechanically cut keys. For an individual customer, any randomly selected security key that has been previously mechanically cut and electronically programmed to the vehicle is acceptable. REFER to Unlimited Key Mode Programming Unlimited Key Mode Programming.

Component Description

Integrated Keyhead Transmitter (IKT)

NOTE: The IKTs (Integrated Keyhead Transmitters) must have SA stamped on the keyblade. Conventional PATS (Passive Anti-Theft System) keys must have HA or SA stamped on the keyblade.





The IKT (Integrated Keyhead Transmitter) incorporates both the PATS (Passive Anti-Theft System) functions and the RKE (Remote Keyless Entry) transmitter functions in a single device.

During key programming procedures, the PATS (Passive Anti-Theft System) and RKE (Remote Keyless Entry) transmitter of an IKT (Integrated Keyhead Transmitter) are both programmed into the BCM (Body Control Module). REFER to Key Programming Using Diagnostic Equipment Key Programming Using Diagnostic Equipment or REFER to Key Programming Using Two Programmed Keys Key Programming Using Two Programmed Keys to program the IKTs (Integrated Keyhead Transmitters). Conventional PATS (Passive Anti-Theft System) keys can also be programmed to the vehicle if requested by the customer.

Up to a maximum of 4 IKTs (Integrated Keyhead Transmitters) can be programmed. If more than 4 IKTs (Integrated Keyhead Transmitters) are programmed, INT KEY COULD NOT PROGRAM is displayed in the message center during the key programming procedure and the RKE (Remote Keyless Entry) function of that IKT (Integrated Keyhead Transmitter) is non-functional.

Passive Anti-Theft System (PATS) Transceiver

The PATS (Passive Anti-Theft System) transceiver reads any key that is placed in the ignition. When the ignition is turned to the ON or START position, the BCM (Body Control Module) activates the PATS (Passive Anti-Theft System) transceiver. Once the transceiver is activated, it in turn activates the key in the ignition and receives the key data. Once the transceiver receives the key data, it sends the data to the BCM (Body Control Module).

Body Control Module (BCM)

The BCM (Body Control Module) is responsible for checking the identification from the PCM (Powertrain Control Module) and checking the key in the ignition. It also controls the ignition states and determines the ignition mode or if the engine should be started depending upon input from the ignition switch.

If the BCM (Body Control Module) is replaced, at least two keys must be programmed and the parameter reset procedure must be performed to enable PATS (Passive Anti-Theft System).

Powertrain Control Module (PCM)

The PCM (Powertrain Control Module) is responsible for allowing starter and fuel injector operation. The PCM (Powertrain Control Module) receives an enable or disable message from the BCM (Body Control Module) over the HS-CAN (High Speed Controller Area Network).

If the PCM (Powertrain Control Module) is replaced, the parameter reset procedure must be performed to enable PATS (Passive Anti-Theft System).