Antitheft and Alarm Systems: Description and Operation

CIRCUIT OPERATION

The Electronic Theft Deterrent System protects not only the vehicle contents, but to offer an extra degree of protection to the vehicle itself, when the system is properly armed. This extra protection is in the form of a "starter interrupt" relay which, when triggered by the controller, opens the circuit between the ignition switch and the starter solenoid thereby preventing vehicle starting.

Alarm Description

The system alarm pulsates the vehicle's horns at a rate of 50 cycles per minute. At the same time the alarm is triggered, the starter interrupt relay is energized which disables the starter solenoid circuit.

In order to conserve vehicle battery power, the alarm shuts off after three to seven minutes of operation and rearms. However, once triggered, the starter interrupt relay will remain energized by the controller until the system has been properly disarmed.

Protective Switches

The doors and rear hatch are equipped with protective switches which will trigger the alarm, if opened while the system is in the armed condition. The switches are located in both door hinge pillars and at the hatch opening.

Each door lock is equipped with a tamper switch which will trigger the alarm if the lock cylinder is tampered with in any way different from the normal mode of operation.

System Fusing

The Electronic Theft Deterrent System is electrically protected by a 10 amp fuse.

Controller

The controller is all electronic and serviced on an exchange basis. The controller operates in two stages: first is the "Armed" stage, and the second is the "Activated" stage.

Starter Interrupt Relay

The starter interrupt relay is a normally closed relay in the starter solenoid circuit. When energized by the controller, the relay contacts are opened, thereby disabling the starter solenoid circuit. The starter interrupt relay is located near the controller and is plugged into the controller harness.

Arming

After the ignition is turned off, the system may be armed at either opened door:

1. With power door locks: Activating the electric door lock switch to the lock position.
2. With manual door locks: Depressing the door lock button to the lock position.

When the last door is closed after a 5 second delay, the system arms.

Disarming

The system is disarmed by unlocking the driver's door with the key or by turning the ignition on. Alarm shut down is accomplished only by unlocking the door with the key.

If the driver wants to prevent arming the system after using the "Door Lock" rocker switch, the switch can be moved to the unlock position before closing all doors. The driver may also cancel the arming process by rotating the ignition switch to the "On" position, then back to lock. Rotating the ignition switch will not cancel the alarm once it is activated.

The doors may be locked mechanically using the door key without arming the system. The door key will disarm and deactivate the system. The ignition key in the ignition lock can only disarm the system (before the alarm is activated).

Automatic Shut Down

Once the alarm has been activated, the starter interrupt relay will be energized and the alarm will continue to operate for a period of three to seven minutes. At the end of the time out period, the alarm will automatically shut off to conserve battery power and, if it locks have not been damaged, the system has been activated, the starter interrupt relay will remain energized until the proper disarming sequence is initiated.