Antitheft and Alarm Systems: Description and Operation
INTRODUCTIONThe Vehicle Theft Security System (VTSS) is designed to protect against whole vehicle theft. The system monitors vehicle doors, trunk key cylinder, and ignition action for unauthorized operation. The alarm activates:
- Sounding of the horn
- Flashing of the park and tail lamps
- Flashing of the headlamps
- An engine kill feature
The electronics for the VTSS are part of the Body Control Module (BCM). The system is armed When the vehicle is locked using the:
- Power door lock switches
- Remote Keyless Entry transmitter.
VTSS Indicator LED:
After the vehicle is locked and the last door is closed, the set LED indicator in the top cover will flash quickly for 16 seconds, indicating that arming is in progress. If no monitored systems are activated during this period, the system will arm. After 16 seconds the indicator LED will continue to flash at a slower rate.
This indicates that the system is armed. If the trunk key cylinder switch is not sensed by the system, the indicator LED will remain lit during the arming process, although the system will still arm. If the indicator LED does not illuminate at all upon door closing it indicates that the system is not arming.
Passive disarming occurs upon normal vehicle entry by unlocking either door with the ignition key/remote transmitter. This disarming will also halt the alarm once it has been activated.
A tamper alert exists to notify the driver that the alarm had been activated. This alert consists of 3 horn pulses when the vehicle is disarmed.
The alarm system will not arm if the doors are locked manually with the ignition key or manually pushing down the door lock mechanism. This will manually override the system.
What Will Trigger The System
Using the power door switch or the keyless transmitter will arm the system. Any of the following actions will trigger the system:
1. Opening any door.
2. Removing the trunk lock cylinder.
3. Turning the ignition to the ON position.
NOTE: The ignition switch can be turned to the accessory position without triggering alarm system.
CIRCUIT OPERATION
The optional Vehicle Theft Security System (VTSS) is used to protect the vehicle from theft by monitoring the vehicle doors, ignition switch, power door lock circuits, and the trunk key cylinder to determine if the alarm should be sounded and the ignition system disabled.
The Body Control Module (BCM) is used as the control for the system. The inputs for the system are divided in two sections. The trunk area and the passenger compartment. If there is a malfunction in the trunk area switch the system will still ARM, but the switch will not be monitored. If the switch becomes functional while the system is ARMED it will be used as an input to the BCM. A problem in any passenger compartment switch will not allow the system to ARM.
The VTSS system uses a Light Emitting Diode (LED) located on the top of the instrument panel to indicate when the system is ARMED. The LED is supplied power on circuit M1. This circuit is the Ignition-Off Draw (IOD) circuit and protected by a 10 amp fuse located in cavity 13 of the junction block. The BCM controls ground for the LED on circuit G69.
Key-In Switch Sense
Circuit G26 is used as an input to the Body Control Module (BCM). This input is used to indicate to the BCM when the ignition is being tampered with. Circuit G26 connects from the key-in switch in the steering column to the BCM.