Antitheft and Alarm Systems: Description and Operation

Anti-Theft

NOTE: The Passive Anti-Theft System (PATS) is available on this vehicle as an option. The vehicle must be ordered with or without PATS by the customer. It is not a dealer-installed option.

NOTE: If the Instrument Cluster (IC) or the PCM is being replaced (or both), the parameters must be reset in both modules or the vehicle experiences a PATS no-start. This occurs even if the vehicle is not equipped with PATS. PATS vehicles and non-PATS vehicles have parameters in the IC and the PCM and they must be reset whenever either (or both) module(s) is (are) replaced. Refer to Passive Anti-Theft System (PATS) Parameter Reset Passive Anti-Theft System (PATS).

PATS vehicles consist of the following components:

- Anti-theft indicator (located in the IC)
- Encoded ignition key(s) (the key contains a transponder)
- PATS transceiver
- IC
- PCM

Non-PATS vehicles consist of the following components:

- Anti-theft indicator (located in the IC)
- Non-PATS ignition key(s) (conventional ignition key)
- IC
- PCM

PATS uses radio frequency identification technology to deter a drive-away theft. Passive means that it does not require any activity by the user.

Passive Anti-Theft System (PATS) Function

The PATS function is controlled by the IC. The PATS uses the IC to carry out all of the PATS functions such as receiving the identification code from the PATS key, issuing a signal to the PCM to control the starter and fuel injectors enable, and initiates the key interrogation sequence when the ignition key is turned to the ON or START position. Because of the interaction between the IC and the PCM, there are parameters that must be set if the IC or the PCM (or both) are replaced. Refer to Passive Anti-Theft System (PATS) Parameter Reset Passive Anti-Theft System (PATS),. If the IC must be replaced for any reason (PATS concerns or Instrument Cluster (IC) concerns), the PATS keys also must be programmed into the new IC. Refer to Key Programming Using Diagnostic Equipment Using Diagnostic Equipment. All elements of PATS must be functional before the vehicle starts. If any of the components are not working correctly, the vehicle does not start.

PATS is not compatible with aftermarket remote start systems, which allow the vehicle to be started from the exterior of the vehicle. These systems may reduce the security of the vehicle, and also may be the cause of no-start concerns.

Passive Anti-Theft System (PATS) Keys

PATS uses a special ignition key that is larger than a conventional ignition key because it contains a permanently installed electronic device called a transponder. Each transponder contains a unique encrypted identification code which is one of a very large number of combinations. The addition of this transponder to the key makes it an "encoded" key. The PATS key does not require batteries and should last the lifetime of the vehicle. Each PATS key must be programmed into the IC before it can be used to start the vehicle. There are special diagnostic procedures described that must be carried out if a new PATS key is necessary. Refer to Key Programming Using Diagnostic Equipment Using Diagnostic Equipment.

Passive Anti-Theft System (PATS) Transceiver

The PATS transceiver is located under the steering column shroud and communicates with the encoded ignition key.

Anti-Theft Indicator Operation

With Passive Anti-Theft System (PATS)

With the key in the OFF position, the anti-theft indicator flashes every 2 seconds for 10 seconds and then it goes out and stays off. With the key in the ON position, the anti-theft indicator proves-out for 3 seconds, then goes out to indicate the PATS is functional and the vehicle has been enabled.

Without Passive Anti-Theft System (PATS)

With the key in the OFF position, the anti-theft indicator does not flash. With the key in the ON position, the anti-theft indicator proves-out for 3 seconds, then goes out to indicate the vehicle has been enabled.

Unlimited Key Mode

PATS contains a feature called unlimited key mode. This feature allows a customer to program more than 8 vehicle keys, if requested. Each vehicle in unlimited key mode is set up with a special unlimited transponder security key code. This allows all 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 Spare Key Programming - Unlimited Key Mode Unlimited Key Mode.