Perimeter Alarm

WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

The BCM controls the operation of the perimeter alarm. It monitors inputs from the RKE system, the passive entry system (if equipped), the power door lock system, the PATS and the ignition status to determine when to arm the perimeter alarm.

The BCM monitors all of the door ajar switches, the hood ajar switch, the TRM (if equipped), the intrusion sensor, the CAN and the ignition status to determine when to activate the perimeter alarm. When the BCM detects an input indicating an unauthorized entry into the vehicle, the BCM activates the perimeter alarm by sounding the traffic horn and flashing all the turn signals and interior courtesy lamps at regular intervals.

The BCM monitors the RKE system, the passive entry system (if equipped), and the PATS to determine when to disarm the perimeter alarm.

A switch inhibit feature temporarily disables the door lock control switches and the tailgate release switch 20 seconds after the vehicle is electronically locked. For detailed information of the switch inhibit feature, Refer to: Handles, Locks, Latches and Entry Systems - System Operation and Component Description .

Visual and audible feedback is also provided when locking or unlocking the vehicle. For detailed information of the vehicle locking and unlocking feedback, Refer to: Handles, Locks, Latches and Entry Systems - System Operation and Component Description .

Arming The Perimeter Alarm

The perimeter alarm is ready to arm any time the ignition is off. The perimeter alarm pre-arms when any of the following occur:

Pressing the lock button on a RKE transmitter
Pressing the door lock control switch to the lock position with a front door open, and then closing the door
Pressing the 7/8 and 9/0 buttons simultaneously on the keyless entry keypad (if equipped)
Locking the vehicle with the passive entry feature (if equipped)

Once the system is pre-armed, there is a 20-second countdown before the perimeter alarm is armed. Each entry point to the vehicle (hood and doors) is armed separately and must be closed before that entry point begins the 20-second countdown to become armed. If all entry points are closed, the turn signals flash upon locking indicating that all entry points are entering the 20-second countdown.

Perimeter Alarm Activation

The perimeter alarm has a 12-second delay when the driver front door is opened without using a valid programmed RKE transmitter, the keyless entry keypad (if equipped) or a passive key (if equipped) 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 (if equipped), the keyless entry keypad (if equipped) or a valid programmed RKE transmitter, and the 12-second delay has expired
Any other door or the hood is opened without first receiving an electronic unlock command from the passive entry feature (if equipped), the keyless entry keypad (if equipped) 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
using a valid programmed key to change the ignition to RUN
entering the correct vehicle unlock code on the keyless entry keypad (if equipped)
unlocking a front door or opening the tailgate using the passive entry feature (if equipped)

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 Key Programming - Scan Tool .