Principles of Operation

WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The perimeter anti-theft system is only available on the MKX. The feature is not available on the Edge.

NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).

The perimeter anti-theft system provides vehicle security through an audible and visual notification if the vehicle doors or the hood is opened without the system being disarmed. The system arms when:

the doors and the hood are closed.
the key is in the OFF position.
the vehicle is electronically locked using the integrated key head transmitter (IKT) key, the keyless entry keypad, or the driver door lock control switch (with the driver door open, then closed).

There is a 20-second pre-arm delay after which each door and hood is armed. If a door or the hood is open, the system still arms all the other closures. Only the open door or hood remains disarmed until it is closed. When the open entry point is closed, that entry point enters a 20-second pre-arm delay, then arms.

The hood switch and door ajar switches register as normally closed. The smart junction box (SJB) monitors the status of the hood switch, and the door ajar switches. If these switches indicate an open entry point, the SJB energizes the horn and flasher relays, causing the horn to sound and the turn signal lamps to flash. The SJB disarms the perimeter alarm when it receives:

an UNLOCK command through the keyless entry keypad.
an UNLOCK command through the IKT key.
an input that the driver door disarm switch (part of the driver door latch) was operated.
a valid passive anti-theft system (PATS) ignition key is turned to the ON position.