The theft deterrent system is a subsystem of the body control module (BCM). This system uses an adjustable shock sensor in the early production units only. The sensor is located inside of the center floor console to sense an intrusion or a shock to the vehicle. The system also uses a Security LED, located in the center floor console, to indicate to the operator the security mode. The BCM can be set by the customer to vary the control of the horn chirps and parking lamp flashes during shock sensor detection. The BCM also senses the position of all door jamb switches to control the lock function during alarm arming. The following circuits connect the BCM to the door jamb switches:

The BCM will only arm the theft deterrent system when the BCM senses that the doors to the above circuits are closed. If the door lock function is detected by the transmitter only and the doors are closed, power is sent to the door lock inversion module through CKT 244 (LT BLU) locking the doors and the alarm will be armed. This will be indicated by the two horn chirps and a headlight flash, plus the security LED will flash once every 2 seconds. If the tailgate or panel doors are open the horn will chirp once. When the lock function is detected by the vehicle door lock switch or the transmitter lock function and any door is open, the alarm will go into "wait" mode and arm when all of the doors are locked. This is indicated by the headlights flash.

Disarming the theft deterrent system is accomplished when the BCM sends power to the door lock inversion module through CKT 245 (DK BLU). In this mode the security LED is off.

Power is fed to both the BCM and the early production model shock sensor at all times from the CTSY fuse #3 through CKT 149 (BLU/WHT). Power is supplied to the security LED from the BCM through CKT 1376 (DK GRN). Power ground for the BCM and the security LED is provided at ground G202 through CKT 150 (BLK). Logic ground for the BCM and ground for the shock sensor is provided through CKT 150 (BLK) to ground G200. Ground is provided to the following components by the BCM when the early production model shock sensor has been triggered or arming mode has been set:

When a tamper with the early production model shock sensor or an intrusion into the vehicle has occurred, the shock sensor sends a signal to the BCM through CKT 263 (LT BLU), which will sound the alarm according to the customer settings. When a shock to the vehicle is detected, the sensor sends a signal to the BCM through CKT 1828 (LT GRN). This also will sound the alarm according to the customer settings.

Refer to Theft Deterrent System (PASSLOCK), 1998 C/K Service Manual.