Antitheft and Alarm Systems: Description and Operation

When triggered, the Anti-theft System honks the horn and flashes the Low Beam Headlamps and Park Lamps at an intermittent rate of approximately 80 cycles per minute. In addition, the Starting System is disabled until the System is disarmed.

ARMING THE SYSTEM

The System is ready to arm any time the Ignition Switch is turned OFF. Voltage to the Central Processing Unit (CPU) from the METER Fuse is removed when the Ignition Switch is in "OFF". Opening a door closes the Door Switch in that door, grounding the "DOOR OPEN INPUT" of the Module. This causes the Central Processing Unit (CPU) to apply a ground signal through the 901 (LG) wire to turn on the Anti-theft Indicator Lamp.

With the Ignition Switch in OFF, locking the doors using the Power Door Lock Switch or using the Keyless Entry Buttons begins the arming sequence. Either of these actions causes the Lock Switches to apply ground to the CPU lock link input terminals K and L. This signals the system to prepare to arm.

System arming can be cancelled before all doors are closed by unlocking the door with the Power Door Lock Switch or by using the Keyless Entry.

The arming cycle is completed by closing all doors. Approximately ten seconds after the last door is closed, the Anti-theft Indicator Lamp turns off, indicating that the system is armed.

TRIGGERING THE SYSTEM

Opening any door or the liftgate without disarming the system triggers the alarm (lamps and horn) for five minutes, even if the door closes. After five minutes, the lamps and horn will turn off and the Central Processing Unit (CPU) will return to an armed state. Also, the starting system is disabled and will remain disabled until the system is disarmed.

When the system is triggered, the CPU applies a pulsing ground to the Headlamp Relay through circuit 262 (W/R) and to the Horn Relay through circuit 323 (GN/O).

At the same time, the CPU prevents current from energizing the Starter Relay. This causes the Starter Relay contacts to open and interrupt current flow to the Starter Motor.

The Luggage Compartment Lamp Switch and Hood Switch are also included in the System. If an attempt is made to open the liftgate or hood, the switch closes and a ground signal is applied to the CPU to trigger the system.

DISARMING THE SYSTEM

To disarm the system, a front door can be unlocked with the key or the keyless entry system can be used.

Unlocking a front door with the key or the Keyless Entry System grounds the CPU's terminal F through circuit 904, signaling the CPU to disarm.