Perimeter Anti-Theft Alarm - System Operation and Component Description

The perimeter alarm has a 12-second delay when the driver front door is opened without using a valid programmed RKE transmitter or a passive key to unlock the vehicle. During the delay, a chime sounds. If the perimeter alarm is not disarmed within the 12-second delay, the alarm activates.

The perimeter alarm activates when:

the driver front door is opened without first receiving an unlock command from the passive entry feature or a valid programmed RKE transmitter, and the 12-second delay has expired. any other door, the luggage compartment lid or the hood is opened without first receiving an electronic unlock command from the passive entry feature or a valid programmed RKE transmitter. the ignition transitions to RUN without a valid PATS key read received. the BCM detects an attempt by a diagnostic scan tool to establish communication on the CAN.

The perimeter alarm only activates 10 times per arming cycle. After that, the alarm does not activate. To enable the perimeter alarm again, disarm the perimeter alarm and then arm it again.

Disarming The Perimeter Alarm

The perimeter alarm disarms when:

pressing the unlock button on a door lock control switch within the 20-second pre-arm. the smart unlock feature activates within the initial 20-second pre-arm. pressing the unlock button on a valid programmed RKE transmitter. pressing the luggage compartment lid release button on a programmed RKE transmitter (this only disarms the luggage compartment lid entry point with the rest of the vehicle remaining armed). using a valid programmed key to change the ignition to RUN. unlocking a front door or opening the luggage compartment lid using the passive entry feature.

CAN Protection Strategy

When the perimeter alarm is armed, the BCM monitors the CAN. If a scan tool is connected to the DLC, and an attempt is made to establish a session with the BCM, it activates the perimeter alarm.

Every time the BCM detects an unauthorized access (alarm activates), all BCM programming, PID monitoring and self-test sessions are blocked for 10 minutes. At the end of the 10 minute time period, the traffic horn chirps to indicate the 1 minute of opportunity to communicate with the BCM and program keys if none are available.

Refer to: Anti-Theft Security Access (419-01B Passive Anti-Theft System (PATS), General Procedures).

Component Description

Door Latch

The door ajar switch, the lock/unlock solenoid and the lock/unlock status input switch are part of the door latch and not serviceable separately.

The door ajar switch is monitored by the BCM and the primary function is for the courtesy lamps system. Refer to: Interior Lighting - System Operation and Component Description (417-02 Interior Lighting, Description and Operation).

The lock/unlock solenoid is controlled by the BCM for locking and unlocking the door. Refer to: Handles, Locks, Latches and Entry Systems - Overview (501-14 Handles, Locks, Latches and Entry Systems, Description and Operation).

The lock/unlock status input switch is used to illuminate the door lock status indicator. Refer to: Handles, Locks, Latches and Entry Systems - Overview (501-14 Handles, Locks, Latches and Entry Systems, Description and Operation).

Hood Ajar Switch

The hood ajar switch is a single pole switch (integrated into the hood latch) that is normally closed when the hood is closed. When the hood is opened, the hood ajar switch opens to indicate an open hood.

The BCM sends a signal to the hood ajar switch, and based on the input, the BCM determines if the hood is open or closed.