Antitheft and Alarm Systems: Description and Operation

Vehicle Theft Security System Components:

GENERAL INFORMATION
This passive system is designed to protect against whole vehicle theft. The system monitors vehicle doors, hood, trunk key cylinder, and ignition action for unauthorized operation. The alarm activates by sounding the horn, flashing the park and tail lamps, and providing an engine kill feature.

Passive arming occurs upon normal vehicle exit (open door, lock with power locks, close door). The "SET" lamp in the panel will flash for 15 seconds, indicating that arming is in progress. If no monitored systems are activated during this period, the system will arm. If the hood or trunk key cylinder switches are not seen by the system, the "SET" lamp will remain steadily lit during the arming process, although the system will still arm.

Passive disarming occurs upon normal vehicle entry (unlocking either door with the key). This disarming will also halt the alarm once it has been activated.

Upon initial installation (connection to battery), the Vehicle Theft Security System enters it power up alarm mode which flashes the park and tail lamps and prevents the engine from running. To exit this mode, the system must be disarmed as mentioned above.

A tamper alert exists to notify the driver that the alarm had been activated, and has since timed-out (alarmed for more than 18 minutes).

This alert consists of 3 horn pulses when the vehicle is disarmed.

The alarm system will not arm if the doors are manually locked, providing a manual override of the alarm.

SYSTEM SELF-TESTS
A diagnostics mode is available in the system to verify operation of all monitored switches or circuits. To enter diagnostics, cycle the ignition key to the accessory position 3 times, leaving the key in this position.

Upon entering diagnostics, the park and tail lamps will begin flashing to verify their operation. In addition, the horn will sound twice to indicate that the trunk key cylinder is in its proper position. Returning the ignition to the OFF position will stop the lamps from flashing while keeping the system in diagnostics.

While in diagnostics mode, a horn pulse should occur at each of the following events indicating proper operation:

1. Beginning with all doors closed, open then close each door. The horn will sound when the door ajar switch closes, and then again when the switch opens. There must be a 1 second delay between closing and opening the switch.
2. Open, then close the hood. The horn will sound when the hood is opened, and again when it is closed.
3. Activate the power door locks in both the "lock" and "unlock" directions. The horn will sound after each activation.
4. Rotate the key in each of the door lock cylinders to the unlock position. The horn will sound as the switch closes, and again when it opens. There must be a 1 second delay between changing switch states, or the horn will not sound.
5. Cycle the key to the ignition RUN position. A single horn pulse will indicate proper operation of the ignition input. This will also take the module out of the diagnostics mode. For any of these tests, if the switch does not remain open or closed for at least 1 second, the horn will only sound once.

The lack of a horn pulse, during any operation, indicates a switch failure, the lack of that input to the Vehicle Theft Security System module, or a failure internal to the module. Check for continuity at the switch, if this is good, check for an open or shorted wire between the switch and alarm module. Also, check if the SBEC has been replaced recently. Vehicle Theft Security System will not function until 20 engine cranks.