Description And Operation: Anti-Theft

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

The perimeter anti-theft system consists of the following:

Door ajar switches
Door disarm switch
Hood switch
Horn
Key-in-ignition switch
Keyless entry keypad
Luggage compartment lid disarm switch
Remote keyless entry (RKE) transmitter
Turn signal lamps
Driver door module (DDM)
Lighting control module (LCM)

The perimeter anti-theft feature is controlled by the LCM. The alarm can be armed by using 1 of 3 commands:

Pressing the LOCK button on the RKE transmitter
Pressing the door lock control switch to LOCK with the accompanying door open, then close the door
Pressing the 7/8 and 9/0 buttons on the keyless entry keypad simultaneously (if equipped)

The DDM monitors the door ajar switches, while the LCM monitors the hood switch, the door disarm switch and the luggage compartment lid disarm switch (all doors, hood, and the luggage compartment lid must be closed and the key must be out of the ignition lock cylinder). The DDM and the LCM communicate this information to each other over the standard corporate protocol (SCP) communication network, and 20 seconds after all of the inputs are closed, the LCM arms the perimeter alarm. From the time each individual input is closed, to the time the perimeter alarm is armed for that particular input, is the "pre-arm phase". The pre-arm phase is separate for each individual input. If the door lock control switch is pressed to LOCK with the accompanying door open, all of the inputs that are closed (hood, luggage compartment lid) immediately begin their pre-arm phase. After the door (that was open) is closed, the doors begin their pre-arm phase. This causes the hood and luggage compartment lid to be armed a few seconds before the doors. The perimeter alarm arms in stages in relation to which input was closed first after the arming command was given.

If the doors are locked, and the driver door is held open, the perimeter alarm will still arm for all of the closed inputs after their 20-second pre-arm phase elapses. If any one of the passenger doors is held open and the system is armed, everything except for the 3 passenger doors will be armed as the 3 passenger doors share the same door ajar circuit.

In the event of an unauthorized entry, the alarm will be activated by the LCM. When the alarm is activated, the LCM intermittently grounds the horn relay, causing the horn to sound in regular intervals, and intermittently powers the turn signals, causing the turn signals to flash in regular intervals.

The perimeter alarm can be disarmed only by:

pressing the UNLOCK button on the RKE transmitter.
turning the door lock cylinder to the UNLOCK position.
using a key to turn the ignition switch to the ON position.
entering the correct vehicle unlock code on the keyless entry keypad (if equipped).

The perimeter alarm can be deactivated (not disarmed), by pressing the PANIC button on the RKE transmitter. This action will not disarm the alarm, but will stop the alarm from activation (horn sounding and turn signals flashing). The perimeter alarm will continue to be armed.