Vehicle Theft Alarm: Notes

The Vehicle Theft Alarm (VTA) is designed to provide either active or passive perimeter protection of the vehicle by monitoring the vehicle doors and the status of the ignition switch (also known as the Keyless Ignition Node/KIN or IGnition Node Module/IGNM). If the VTA system detects any attempt to compromise a monitored vehicle system or feature, the vehicle horn is pulsed as an audible deterrent and certain exterior lamps are flashed as a visual deterrent.

The Body Control Module (BCM) (also known as the Common Body Controller/CBC) includes the logic and control circuits for the VTA. Each of the ajar switches provides hard wired inputs to the BCM, while the BCM provides control outputs to the vehicle horn and lighting systems. The Radio Frequency Hub Module (RFHM) (also known as the RF Hub) monitors the status of the ignition switch through a private serial bus and relays this information to the BCM in the form of electronic messages transmitted over the Controller Area Network (CAN) data bus.

The hard wired circuits between components related to the VTA system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the VTA system or the electronic controls and communication between modules and devices that provide some features of the VTA system. The most reliable, efficient and accurate means to diagnose the VTA system or the electronic controls and communication related to VTA system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.