Ford Explorer: Perimeter Anti-Theft Alarm / Description and Operation - Perimeter Anti-Theft Alarm - System Operation and Component Description

System Operation

System Diagram

Network Message Chart

  Module Network Input Messages - BCM

  Module Network Input Messages - IPC

Perimeter Alarm

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 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 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.

Perimeter Alarm Arming

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

• Locking a front door or the liftgate using the passive entry feature (if equipped)
• Pressing the door lock control switch to the lock position with a front door open, and then closing the door
• Pressing the lock button on a programmed RKE transmitter
• Touching the 7/8 and 9/0 buttons simultaneously on the keyless entry keypad (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, door, 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 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 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 any of the following actions are performed:

• 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 programmed RKE transmitter, and the 12 second delay has expired.
• Any other door, liftgate, 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 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 and arm it again.

Perimeter Alarm Disarming

The perimeter alarm disarms when any of the following actions are performed:

• Entering the correct vehicle unlock code on the keyless entry keypad (if equipped).
• Pressing the unlock button on a door lock control switch within the 20 second pre-arm timeframe.
• Pressing the unlock button on a programmed RKE transmitter.
• Using a programmed key to change the ignition to RUN.
• Unlocking a front door or the liftgate using the passive entry feature (if equipped).

CAN Protection Strategy

When the perimeter alarm is armed, the BCM monitors the CAN. If a diagnostic 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 horn chirps to indicate the 1 minute of opportunity to communicate with the BCM and program keys if none are available. For vehicles without push button start,
Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description (419-01B Passive Anti-Theft System (PATS), Description and Operation).
For vehicles with push button start,
Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description (419-01C Passive Anti-Theft System (PATS) - Vehicles With: Keyless Vehicle System, Description and Operation).

Component Description

BCM

The BCM controls the operation of the perimeter alarm. Based on input, the BCM arms, disarms, activates or deactivates the perimeter alarm.

The BCM requires PMI when replaced. Additionally, at least 2 keys must be programmed and the parameter reset procedure carried out.

Door Ajar Switch

The door ajar switch is a single pole switch monitored by the BCM. The primary function of the door ajar switch is for the courtesy lamps system.
Refer to: Interior Lighting - System Operation and Component Description (417-02 Interior Lighting, Description and Operation).

Door Latch

The door ajar switch and the lock/unlock solenoid, are part of the door latch and not serviceable separately.

The door ajar switch is monitored by the BCM and the primary function is for the courtesy lamps system.
Refer to: Interior Lighting - System Operation and Component Description (417-02 Interior Lighting, Description and Operation).

The lock/unlock solenoid is controlled by the BCM for locking and unlocking the door.
Refer to: Handles, Locks, Latches and Entry Systems - System Operation and Component Description (501-14 Handles, Locks, Latches and Entry Systems, Description and Operation).

Hood Ajar Switch

The hood ajar switch is a single pole switch integrated into the hood latch and is normally open when the hood is closed. When the hood is opened, the hood ajar switch closes to indicate an open hood.

The BCM sends a voltage signal to the hood ajar switch and based on the input, the BCM determines if the hood is open or closed.