Principles of Operation: Notes

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 driver door module (DDM) monitors the door ajar circuits, while the lighting control module (LCM) monitors the hood switch, the door disarm switch and the luggage compartment lid disarm switch. 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, if there has been a request to arm the perimeter alarm, the LCM arms the perimeter alarm. When the DDM or the LCM receives a signal from one or more of the monitored switch(es) indicating unauthorized entry into the vehicle, the LCM intermittently grounds the horn relay and also intermittently sends voltage to the turn signal lamps. The horn relay closes, supplying voltage to the horn. The LCM cycles the ground to the horn relay and voltage to the turn signal lamps, on and off in regular intervals, while the system is activated. An activated alarm can either be deactivated or disarmed. Pressing the PANIC button on the remote keyless entry (RKE) transmitter will deactivate the perimeter alarm, but will not disarm the alarm. The LCM monitors the key-in-ignition switch and does not allow the perimeter anti-theft feature to arm until after the key is removed from the ignition lock cylinder, all doors/hood/luggage compartment lid are closed and 20 seconds have elapsed after locking the vehicle. Each input has its own 20-second pre-arm phase, depending on when they were closed after the arm command was given. After all of these criteria have been met, the anti-theft feature will arm.

The perimeter anti-theft feature can be armed by either:

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

The perimeter anti-theft feature (or an activated alarm) can be disarmed when either:

an unlock request is made through the RKE transmitter.
the driver door is unlocked with a key.
the ignition switch is turned to the ON position using a key.
unlocking the vehicle using the keyless entry keypad (if equipped).

Pressing the PANIC button on the RKE transmitter will also deactivate the perimeter alarm, but will not disarm the alarm.