General Information; Disarming; Power-Up Mode; Tamper Alert - Jeep 1997 Grand Cherokee Service Manual

8Q - 2 VEHICLE THEFT/SECURITY SYSTEMS
GENERAL INFORMATION (Continued)
still arm if the hood is open, but the engine compart-
ment will not be protected. Once the 15 second arm-
ing function is complete, the set lamp will flash at a
slower rate to indicate that the VTSS is armed.

DISARMING

Passive disarming of the VTSS occurs when the
vehicle is unlocked using the key to unlock either
front door or the liftgate. Active disarming of the
VTSS occurs when the vehicle is unlocked by
depressing the Unlock button of the RKE transmit-
ter.
Once the alarm has been activated (horn sounding,
lights flashing, and the engine no-run feature), either
disarming method will also deactivate the alarm.
Depressing the Panic button on the RKE transmit-
ter will also disarm the VTSS, but the horn will
sound and the lights will flash for about three min-
utes as part of the Panic feature. Refer to Group 8P -
Power Lock Systems for more information on the
Panic feature.

POWER-UP MODE

When the armed VTSS senses that the battery has
been disconnected and reconnected, it enters its pow-
er-up mode. In the power-up mode the alarm system
remains armed following a battery failure or discon-
nect. If the VTSS was armed prior to a battery dis-
connect or failure, the system will have to be actively
or passively disarmed following a battery reconnec-
tion.
The power-up mode will also apply if the battery
goes dead while the system is armed, and battery
jump-starting is attempted. The engine no-run fea-
ture will prevent the engine from starting until the
alarm system has been actively or passively dis-
armed.

TAMPER ALERT

The VTSS tamper alert will sound the horn three
times upon disarming, if the alarm was activated and
has since timed-out (about eighteen minutes). This
feature alerts the driver that the VTSS was activated
while the vehicle was unattended.

DESCRIPTION AND OPERATION

BODY CONTROL MODULE

A Body Control Module (BCM) is used on this
model to control and integrate many of the electronic
functions and features on the vehicle. The BCM con-
tains a central processing unit and interfaces with
other modules in the vehicle on the Chrysler Colli-
sion Detection (CCD) data bus network.
The CCD data bus network allows the sharing of
sensor information. This helps to reduce wire har-
ness complexity, reduce internal controller hardware,
and reduce component sensor current loads. At the
same time, this system provides increased reliability,
enhanced diagnostics, and allows the addition of
many new feature capabilities.
One of the functions and features that the BCM
supports and controls, is the Vehicle Theft Security
System (VTSS). In addition to the information
received on the CCD data bus, the BCM receives
hard-wired inputs from the door ajar, door lock cylin-
der, hood, liftgate ajar, liftgate lock cylinder, and lift-
glass ajar switches. In its role as the VTSS controller,
the programming in the BCM allows it to process the
information from all of its inputs and send control
outputs to energize or de-energize the auto headlamp
relay, horn relay, park lamp relay, Powertrain Con-
trol Module (PCM), and the security set lamp.
The BCM is mounted under the driver side out-
board end of the instrument panel, behind the instru-
ment panel support
outboard switch pod. Refer to Group 8E - Instrument
Panel Systems for the removal and installation pro-
cedures. For diagnosis of the BCM or the CCD data
bus, refer to the proper Body Diagnostic Procedures
manual. The BCM can only be serviced by an autho-
rized electronic repair station. Refer to the latest
Warranty Policies and Procedures manual for a cur-
rent listing of authorized electronic repair stations.

HOOD SWITCH

The hood switch is mounted to the right inner
fender ledge, under the hood and near the battery. It
is a plunger-type switch that is case grounded to the
fender shield. When the hood is open the switch is
closed, and when the hood is closed the switch is
open.
The hood switch cannot be repaired and, if faulty
or damaged, it must be replaced.

DOOR AJAR SWITCH

The door ajar switches are mounted to the pillar in
the rear of each door opening. They are plunger-type
switches that are case grounded to the pillar. When
the door is open the switch is closed, and when the
door is closed the switch is open.
The door ajar switches cannot be repaired and, if
faulty or damaged, they must be replaced.

DOOR LOCK CYLINDER SWITCH

The door lock cylinder switches are mounted to the
back of the key lock cylinder inside each front door.
They are normally-open momentary switches that
close to ground only when the lock cylinder is rotated
to the unlock position.
The door lock cylinder switches cannot be repaired
and, if faulty or damaged, they must be replaced.
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