Vehicle Theft Alarm

OPERATION 

The Body Control Module (BCM) includes the logic and control circuits for the Vehicle Theft Alarm (VTA). Each of the ajar switches provides hard wired inputs to the BCM, while the BCM provides control outputs to the vehicle horns and lighting systems. The Radio Frequency Hub (RF-Hub) monitors the status of the Keyless Ignition Node (KIN) through a private security K-line data bus and relays this information to the BCM as electronic messages transmitted over the Controller Area Network-Chassis (CAN-C) data bus.

OPERATING MODES 

Following are paragraphs that briefly describe the operation of each of the VTA operating modes.

• Enabling  - The BCM and the RF-Hub must have the VTA function electronically enabled in order for the VTA to perform as designed.
• Alarm  - The VTA alarm output provides both visual and audible outputs; however, the time intervals of these outputs vary by the requirements of the market for which the vehicle is manufactured. In all cases, the visual output will be a flashing On and Off of the exterior turn signal lamps, while the audible output will be either a pulsing of the horn or, if the vehicle is so equipped, the siren. The inputs that will trigger the alarm include a change in the status of the ignition, the door ajar switches and the hood ajar switch.
• Arming  - Arming of the VTA occurs when the vehicle is exited and the status of the KIN (with PEKG) is OFF, the exterior lighting is turned Off, then the Lock button on the Remote Keyless Entry (RKE) transmitter is depressed or the Lock button on the Passive Entry (PE) is pressed to lock the vehicle. For active arming to occur, all doors must be closed and the status of the KIN must be Off when the RKE transmitter or PE handle Lock button is depressed. Arming will not occur if a key fob is within the vehicle interior.

  Pre-arming of the VTA is initiated when a door is open when the vehicle is locked using a power door lock switch or when the RKE Lock button is pressed. Pre-arming will not occur if a key fob is within the vehicle interior. When the VTA is pre-armed, the arming sequence is delayed 16 seconds until all of the doors have been closed.

  Once the VTA begins the arming sequence, the security indicator in the Instrument Panel Cluster (IPC) will flash rapidly for about 16 seconds. This indicates that VTA arming is in progress. If the status of the ignition changes, if a door is unlocked or opened by any means, the security indicator will stop flashing and the arming process will abort. Once the arming sequence is successfully completed, the security indicator will flash at a slower rate, indicating that the VTA is armed.

  The VTA arming sequence will occur regardless of whether a door is open or closed, but the security indicator will illuminate solid and the open door will not be protected unless the door is closed when the VTA arming sequence first begins.

  The VTA arming sequence will occur regardless of whether the hood ajar switch is open or closed, but the security indicator will illuminate solid and the engine compartment will not be protected unless the hood is closed when the VTA arming sequence first begins. Also, if the status of the hood ajar switch changes from open to closed during the 16 second arming process, the security indicator will switch from solid to flashing. Once the arming process is successfully completed, the security indicator will flash at a slower rate, indicating that the VTA is armed.

• Disarming  - Passive disarming of the VTA occurs when the vehicle is unlocked by depressing the Unlock button of the RKE transmitter. Once the alarm has been activated, this disarming method will also deactivate the alarm. If one of the valid key fob units is located outside the vehicle and within 1.5 meters (5 feet) of the driver or passenger front door handles, grab the PE handle and enter the vehicle, then press the KIN to transition the ignition status to ON. This requires at least one valid key fob be located within the passenger compartment of the vehicle.
• Power-Up Mode  - When the armed VTA senses that the battery has been disconnected and reconnected, it enters its power-up mode. In the power-up mode the armed alarm system remains armed following a battery failure or disconnect. If the VTA was armed prior to a battery disconnect or failure, the technician or vehicle operator will have to disarm the alarm system after the battery is reconnected. The power-up mode will also apply if the battery goes dead while the system is armed, and battery jump-starting is attempted. The VTA will be armed until the technician or vehicle operator has disarmed the alarm system. If the VTA is in the disarmed mode prior to a battery disconnect or failure, it will remain disarmed after the battery is reconnected or replaced, or if jump-starting is attempted.
• Tamper Alert  - The VTA tamper alert feature will illuminate an icon in the IPC when the ignition first transitions to ON if the alarm was triggered and has since timed out, or if the battery has been disconnected and reconnected. This feature alerts the vehicle operator that the VTA alarm was activated while the vehicle was unattended.