Vehicle Theft Alarm System

The Vehicle Theft Alarm (VTA) is a logic-controlled system. It monitors the vehicle doors, hood, trunk, key cylinder, and ignition for unauthorized operation. (For connector pinouts, see HELP 3 - Inspection of Electrical Connectors.)

The system has the following components: Vehicle Theft Alarm Control Module; four door alar switches; hood alar switch and striker; trunk key cylinder sensing switch; two door key cylinder disarming switches; instrument panel "set" lamp; engine controller; horn and horn relay; park and tail lamps; power door lock circuits; ignition switch.

When an unauthorized entry to the vehicle occurs, the VTA module sends a message via the CCD bus to the engine controller that it is not OK to start the engine. The engine controller then zeroes out the pulse width to the fuel injectors after the engine has been started, thus shutting down the engine (start and stall condition).

The VTA module has the capability of providing bias on the CCD bus when the body controller is powered down.

To avoid both an audible alarm and the engine kill feature causing a problem in the assembly plant, an initialization procedure is included in the VTA system. This procedure requires that the vehicle has recorded 20 engine cranks. Therefore, the VTA system will not be functional on all vehicles and will require dealer verification.

In addition, when an engine controller has been replaced, 20 engine cranks must be reached before the theft alarm becomes operational.

To verify the system, proceed as follows:
1. Open the driver's door.
2. Remove the ignition key (but keep it in hand).
3. Lock the doors with the power lock switch.
4. Close the driver's door.
5. If the instrument panel theft alarm "SET" lamp flashed, the system is operational and verified. If not, 20 engine cranks have not occurred, or there is a problem with the vehicle theft alarm system.