Perimeter Alarm

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. 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 (includes the keyless entry keypad), the power door lock system and the passive entry system to determine when to arm the perimeter alarm.

The BCM monitors all of the door ajar switches, the liftgate ajar switch and the hood ajar switch 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 horn and flashing all the turn signals and interior courtesy lamps at regular intervals.

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

Arming the Perimeter Alarm

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

pressing the lock button on a valid programmed RKE transmitter.
pressing the door lock control switch to the lock position with the door open, and then closing the door.
touching the 7/8 and 9/0 buttons simultaneously on the keyless entry keypad.

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, doors and liftgate) 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 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 door is unlocked and opened using a key in the door lock cylinder. During the delay, a chime sounds and Vehicle Alarm To Stop Alarm, Start Vehicle displays in the message center. If the perimeter alarm is not disarmed within the 12-second delay, the alarm activates.

The perimeter alarm activates when:

the driver door is opened without first receiving an unlock command from a valid programmed RKE transmitter or keyless entry keypad, and the 12-second delay has expired.
any passenger door, the liftgate, or the hood is opened without first receiving an electronic unlock command from a valid programmed RKE transmitter or keyless entry keypad or the passive entry system.

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 valid programmed RKE transmitter.
pressing the liftgate release button on a valid programmed RKE transmitter.
opening the a door using the passive entry feature.
using a programmed passive key to change the ignition state out of OFF.
entering the correct vehicle unlock code on the keyless entry keypad.

The perimeter alarm can be deactivated by pressing the panic button on a valid programmed RKE transmitter. All of the lamps stop flashing and the horn stops sounding, but the alarm is still armed.

Passive Key Disable

For security reasons, when the perimeter alarm enters an armed state, the RFA module searches the interior of the vehicle for any programmed passive keys. If the RFA module detects any programmed passive key inside the vehicle when the perimeter alarm is armed, it disables that passive key. The RKE and the passive entry functions of that key still operate, but the RFA module ignores any start command associated with that key. The disabled passive key enables when the perimeter alarm disarms.