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.
- If the instrument cluster (IC) or the PCM is being replaced (or both), the parameters must be reset in both modules or the vehicle will experience a PATS no-start. This will occur 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
- CM

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

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. If the IC must be replaced for any reason (PATS concerns or IC concerns), the PATS keys also must be programmed into the new IC. Refer to Key Programming Using Diagnostic Equipment. All elements of PATS must be functional before the vehicle will start. If any of the components are not working correctly, the vehicle will not start. Passive Anti-Theft System (PATS) Using Diagnostic Equipment

PATS may cause a vehicle no start due to either the fuel injectors or the starter not operating, or both. Always check for PATS DTCs from the IC and the PCM when a no-crank or no-start condition exists. A low state of charge (SOC) in the vehicle battery may cause the PATS to allow the starter to crank the engine, but prevent the fuel injectors from operating. If the theft light does not prove out (it may be either flashing or glowing steadily) and one (or both) of the previous conditions (fuel injectors and/or engine won't crank) are present, it may be due to a PATS issue. If the theft light proves out, it may not be a PATS issue. If the theft light does not illuminate at all, it may be an IC issue. GO to Symptom Chart. Symptom Related Diagnostic Procedures

The PATS function uses the IC and the PCM to enable or disable the engine. All elements of PATS must be functional before the engine is allowed to start. If any of the components are not working correctly, the vehicle will not start. If there is a PATS concern present, the IC will send a message to the PCM to not allow fuel injector operation and also not allow starter operation. If the vehicle starts and stalls, or the engine will not start at all, check the anti-theft indicator operation and if it is flashing or glowing, retrieve DTCs from the IC and the PCM and follow the PATS diagnostics.

PATS is active only for a few seconds when the vehicle is starting. It is not a PATS concern if the vehicle stalls after it has been running for a minimum of 3 seconds. PATS will not disable a running vehicle.

PATS will not disable a running vehicle. 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. Remote start systems must be removed from the vehicle before any PATS-related no-start concerns are investigated. If the remote start system is a Power Code(R) system, make certain it is not the cause of the no-start. Removal of the system may be necessary.

Anti-Theft Indicator Operation

With PATS
With the key in the OFF position, the anti-theft indicator will flash every 2 seconds for 10 seconds and then it will go out and stay off. With the key in the ON position, the anti-theft indicator will prove-out for 3 seconds, then go out to indicate the PATS is functional and the vehicle has been enabled.

Without PATS
With the key in the OFF position, the anti-theft indicator will not flash. With the key in the ON position, the anti-theft indicator will prove-out for 3 seconds, then go 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 is acceptable. Refer to Spare Key Programming - Unlimited Key Mode. Unlimited Key Mode