2003 JEEP GRAND CHEROKEE Body control module

SIDE CURTAIN AIRBAG
DESCRIPTION
Optional side curtain airbags are available for this
model when it is also equipped with dual front air-
bags. These airbags are passive, inflatable, Supple-
mental Restraint System (SRS) components, and
vehicles with this equipment can be readily identified
by a molded identification trim button with the ªSRS
- AIRBAGº logo located on the headliner above each
B-pillar (Fig. 42). This system is designed to reduce
injuries to the vehicle occupants in the event of a
side impact collision.
Vehicles equipped with side curtain airbags have
two individually controlled curtain airbag units.
These airbag units are concealed and mounted above
the headliner where they are each secured to one of
the roof side rails (Fig. 43). Each folded airbag cush-
ion is contained within a long extruded plastic chan-
nel that extends along the roof rail from the A-pillar
at the front of the vehicle to just behind the C-pillar
at the rear of the vehicle. One tether extends down
the A-pillar from the front of the airbag cushion, and
a second tether extends to the roof rail above the
D-pillar. The ends of these tethers are secured to
slots in the sheet metal with metal hooks retained by
plastic anchor clips.
The hybrid-type inflator for each airbag is secured
to the roof rail at the rear of the airbag unit between
the C-pillar and the D-pillar, and is connected to the
airbag cushion by a long tubular manifold. The infla-
tor bracket and the extruded airbag cushion channel
are secured with both plastic push-in fasteners and
screws to the roof rail. A dedicated two-wire take out
and connector of the body wire harness is routed for-
ward from the D-pillar to the airbag inflator.The side curtain airbag unit cannot be adjusted or
repaired and must be replaced if deployed, faulty, or
in any way damaged. Once a side curtain airbag has
been deployed, the complete airbag unit, the head-
liner, the upper A, B, and C-pillar trim, and all other
visibly damaged components must be replaced.
OPERATION
Each side curtain airbag is deployed individually
by an electrical signal generated by the Airbag Con-
trol Module (ACM) to which it is connected through
left or right curtain airbag line 1 and line 2 (or
squib) circuits. The hybrid-type inflator assembly for
each airbag contains a small canister of highly com-
pressed gas. When the ACM sends the proper electri-
cal signal to the airbag inflator, the electrical energy
creates enough heat to ignite chemical pellets within
the inflator. Once ignited, these chemicals burn rap-
idly and produce the pressure necessary to rupture a
containment disk in the pressurized gas canister. The
inflator and gas canister are sealed and connected to
a tubular manifold so that all of the released inert
gas is directed into the folded side curtain airbag
cushion, causing the cushion to inflate.
As the airbag cushion inflates it will drop down
from the roof rail between the edge of the headliner
and the side glass/body pillars to form a curtain-like
cushion to protect the vehicle occupants during a side
impact collision. The front and rear tethers keep the
side curtain bag taut, thus ensuring that the bag will
deploy in the proper position. Following the airbag
deployment, the airbag cushion quickly deflates by
venting the inert gas through the loose weave of the
cushion fabric, and the deflated cushion hangs down
loosely from the roof rail.
REMOVAL
The following procedure is for replacement of a
faulty or damaged side curtain airbag. If the airbag
is faulty or damaged, but not deployed, review the
recommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTAL
RESTRAINTS). If the side curtain airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).
Fig. 42 SRS Logo
WJRESTRAINTS 8O - 39

INSTALLATION
The following procedure is for replacement of a
faulty or damaged side curtain airbag. If the airbag
is faulty or damaged, but not deployed, review the
recommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTAL
RESTRAINTS). If the side curtain airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: WHEN REMOVING A DEPLOYED AIR-
BAG, RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG UNIT AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
WARNING: USE EXTREME CARE TO PREVENT ANY
FOREIGN MATERIAL FROM ENTERING THE SIDE
CURTAIN AIRBAG, OR BECOMING ENTRAPPED
BETWEEN THE SIDE CURTAIN AIRBAG CUSHION
AND THE HEADLINER. FAILURE TO OBSERVE THIS
WARNING COULD RESULT IN OCCUPANT INJURIES
UPON AIRBAG DEPLOYMENT.
(1) Position the side curtain airbag into the vehicle
as a unit.(2) Align the push-in fastener that secures the
inflator of the side curtain airbag to the locating hole
in the roof side rail and, using hand pressure, push
firmly on the retainer until it is fully seated (Fig. 45).
(3) Align the three push-in fasteners that secure
the extruded plastic channel of the side curtain air-
bag to the locating holes in the roof side rail and,
using hand pressure, push firmly on each retainer
until it is fully seated.
(4) Install and tighten the nine screws that secure
the side curtain airbag channel and inflator mount-
ing bracket to the spring nuts in the roof side rail.
Tighten the screws to 6 N´m (50 in. lbs.).
(5) Align the side curtain airbag front tether plas-
tic retainer with the hole in the upper A-pillar and,
using hand pressure, push firmly on the retainer
until it is fully seated.
(6) Engage the side curtain airbag front tether
hook and plastic retainer clip into the slot in the
lower A-pillar.
(7) Engage the side curtain airbag rear tether
hook and plastic retainer clip into the slot in the roof
rail near the D-pillar (Fig. 44).
(8) Reconnect the body wire harness connector for
the side curtain airbag inflator to the inflator connec-
tor receptacle.
(9) Reinstall the headliner into the vehicle. (Refer
to 23 - BODY/INTERIOR/HEADLINER - INSTALLA-
TION).
(10) Do not reconnect the battery negative cable at
this time. The supplemental restraint system verifi-
cation test procedure should be performed following
service of any supplemental restraint system compo-
nent. (Refer to 8 - ELECTRICAL/RESTRAINTS -
STANDARD PROCEDURE - VERIFICATION TEST).
SIDE IMPACT SENSOR
DESCRIPTION
Two side impact sensors are used on this model
when it is equipped with the optional side curtain
airbags, one each for the left and right sides of the
vehicle (Fig. 46). These sensors are mounted
remotely from the bi-directional safing sensor that is
internal to the Airbag Control Module (ACM). The
side and front impact sensors are identical in con-
struction and calibration with the exception of the
right-hand and left-hand die cast aluminum mount-
ing brackets to which each front impact sensor is
secured with two screws. The side impact sensors are
secured with two screws to the base of the right and
left B-pillars just below the front seat belt retractors
and behind the lower B-pillar trim within the pas-
senger compartment.
8O - 42 RESTRAINTSWJ
SIDE CURTAIN AIRBAG (Continued)

The impact sensor housing has an integral connec-
tor receptacle and two integral mounting ears, each
with a metal sleeve to provide crush protection. A
cavity in the center of the molded black plastic
impact sensor housing contains the electronic cir-
cuitry of the sensor which includes an electronic com-
munication chip and an electronic impact sensor.
Potting material fills the cavity to seal and protect
the internal electronic circuitry and components. The
side impact sensors are each connected to the vehicle
electrical system through a dedicated take out and
connector of the airbag overlay wire harness.
The side impact sensors cannot be repaired or
adjusted and, if damaged or faulty, they must be
replaced.
OPERATION
The side impact sensors are electronic accelerome-
ters that sense the rate of vehicle deceleration, which
provides verification of the direction and severity of
an impact. Each sensor also contains an electronic
communication chip that allows the unit to commu-
nicate the sensor status as well as sensor fault infor-
mation to the microprocessor in the Airbag Control
Module (ACM). The ACM microprocessor continu-
ously monitors all of the passive restraint system
electrical circuits to determine the system readiness.
If the ACM detects a monitored system fault, it sets
a Diagnostic Trouble Code (DTC) and controls the
airbag indicator operation accordingly.
The impact sensors each receive battery current and
ground through dedicated left and right sensor plus
and minus circuits from the ACM. The impact sensors
and the ACM communicate by modulating the voltage
in the sensor plus circuit. The hard wired circuits
between the side impact sensors and the ACM may bediagnosed and tested using conventional diagnostic
tools and procedures. However, conventional diagnos-
tic methods will not prove conclusive in the diagnosis
of the ACM or the impact sensors. The most reliable,
efficient, and accurate means to diagnose the impact
sensors, the ACM, and the electronic message commu-
nication between the sensors and the ACM requires
the use of a DRBIIItscan tool. Refer to the appropri-
ate diagnostic information.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: THE SIDE IMPACT SENSOR ENABLES
THE SYSTEM TO DEPLOY THE SIDE CURTAIN AIR-
BAG. NEVER STRIKE OR DROP THE SIDE IMPACT
SENSOR, AS IT CAN DAMAGE THE IMPACT SEN-
SOR OR AFFECT ITS CALIBRATION. IF AN IMPACT
SENSOR IS ACCIDENTALLY DROPPED DURING
SERVICE, THE SENSOR MUST BE SCRAPPED AND
REPLACED WITH A NEW UNIT. FAILURE TO
OBSERVE THIS WARNING COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER SIDE CUR-
TAIN AIRBAG DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the trim from the lower right or left
B-pillar. (Refer to 23 - BODY/INTERIOR/B-PILLAR
LOWER TRIM - REMOVAL).
(3) Disconnect the airbag overlay wire harness
connector for the right or left side impact sensor from
the sensor connector receptacle (Fig. 47).
(4) Remove the two screws that secure the right or
left side impact sensor to the B-pillar.
(5) Remove the side impact sensor from the B-pil-
lar.
Fig. 46 Side Impact Sensor
1 - SENSOR
2 - CONNECTOR RECEPTACLE
WJRESTRAINTS 8O - 43
SIDE IMPACT SENSOR (Continued)

SPECIFICATIONS
TORQUE - SPEED CONTROL
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Servo Mounting Bracket-to-
Servo Nuts8.5 75
Servo Mounting Bracket-to-
Body Nuts28 6 250 50
Switch Module Mounting
Screws.6-1 6-9
Vacuum Reservoir Mounting
Bolts325
CABLE
DESCRIPTION
The speed control servo cable is connected between
the speed control vacuum servo diaphragm and the
throttle body control linkage.
OPERATION
This cable causes the throttle control linkage to
open or close the throttle valve in response to move-
ment of the vacuum servo diaphragm.
REMOVAL
REMOVAL - 4.0L
(1) Disconnect negative battery cable at battery.
(2) Remove air box housing from throttle body.
(3) Using finger pressure only, remove speed con-
trol cable connector at throttle body bellcrank pin by
pushing connector off bellcrank pin towards drivers
side of vehicle (Fig. 1).DO NOT try to pull con-
nector off perpendicular to the bellcrank pin.
Connector will be broken.
(4) Remove cable from cable guide at top of valve
cover.
(5) Squeeze 2 release tabs (Fig. 1) on sides of cable
at bracket and push cable out of bracket.
(6) Remove servo cable from servo. Refer to Speed
Control Servo Removal/Installation.
REMOVAL - 4.7L
(1) Disconnect negative battery cable at battery.
(2) Remove air box housing from throttle body.
The accelerator cable must be partially removed to
gain access to speed control cable.(3) Using finger pressure only, disconnect accelera-
tor cable connector at throttle body bellcrank pin by
pushing connector off bellcrank pin towards front of
vehicle (Fig. 2).DO NOT try to pull connector off
perpendicular to the bellcrank pin. Connector
will be broken.
Fig. 1 Speed Control Cable at Bell CrankÐ4.0L
Engine
1 - ACCELERATOR CABLE
2 - OFF
3 - OFF
4 - THROTTLE BODY BELLCRANK
5 - SPEED CONTROL CABLE
6 - RELEASE TABS
7 - BRACKET
WJSPEED CONTROL 8P - 3
SPEED CONTROL (Continued)

(8) Connect negative battery cable at battery.
(9) Before starting engine, operate accelerator
pedal to check for any binding.
SERVO
DESCRIPTION
The servo unit consists of a solenoid valve body,
and a vacuum chamber. The solenoid valve body con-
tains three solenoids:
²Vacuum
²Vent
²Dump
The vacuum chamber contains a diaphragm with a
cable attached to control the throttle linkage.
OPERATION
The Powertrain Control Module (PCM) controls the
solenoid valve body. The solenoid valve body controls
the application and release of vacuum to the dia-
phragm of the vacuum servo. The servo unit cannot
be repaired and is serviced only as a complete assem-
bly.
Power is supplied to the servo's by the PCM
through the brake switch. The PCM controls the
ground path for the vacuum and vent solenoids.The dump solenoid is energized anytime it receives
power. If power to the dump solenoid is interrupted,
the solenoid dumps vacuum in the servo. This pro-
vides a safety backup to the vent and vacuum sole-
noids.
The vacuum and vent solenoids must be grounded
at the PCM to operate. When the PCM grounds the
vacuum servo solenoid, the solenoid allows vacuum
to enter the servo and pull open the throttle plate
using the cable. When the PCM breaks the ground,
the solenoid closes and no more vacuum is allowed to
enter the servo. The PCM also operates the vent sole-
noid via ground. The vent solenoid opens and closes a
passage to bleed or hold vacuum in the servo as
required.
The PCM duty cycles the vacuum and vent sole-
noids to maintain the set speed, or to accelerate and
decelerate the vehicle. To increase throttle opening,
the PCM grounds the vacuum and vent solenoids. To
decrease throttle opening, the PCM removes the
grounds from the vacuum and vent solenoids. When
the brake is released, if vehicle speed exceeds 30
mph to resume, 35 mph to set, and the RES/ACCEL
switch has been depressed, ground for the vent and
vacuum circuits is restored.
REMOVAL
The speed control servo is attached to a bracket.
The bracket and servo assembly are located below
the battery tray.
(1) Disconnect negative battery cable at battery.
(2) Disconnect positive battery cable at battery.
(3) Remove air cleaner housing at top of throttle
body and disconnect servo cable at throttle body.
Refer to Servo Cable Removal/Installation.
(4) Remove battery from battery tray.
(5) Disconnect wiring at battery tray.
(6) Disconnect positive battery cable at Power Dis-
tribution Center (PDC).
(7) Loosen PDC at battery tray.
(8) Remove 4 battery tray bolts. One of these bolts
attaches to speed control bracket flange that sup-
ports battery tray. While removing battery tray, dis-
connect battery temperature sensor electrical
connector at sensor.
(9) Disconnect vacuum line at servo vacuum hose
fitting (Fig. 5) .
(10) Disconnect electrical connector at servo (Fig.
5) .
If servo and mounting bracket are being removed
as one assembly, remove two mounting nuts (Fig. 5) .
These are located above right-front tire. Remove
inner fender clips and pry inner fender back slightly
to gain access to mounting nuts.
Fig. 4 Speed Control Cable at BracketÐ4.7L V-8
Engine
1 - PLASTIC CABLE MOUNT
2 - SPEED CONTROL CABLE
3 - BRACKET
4 - SLIDE FOR REMOVAL
WJSPEED CONTROL 8P - 5
CABLE (Continued)

VEHICLE THEFT SECURITY
TABLE OF CONTENTS
page page
VEHICLE THEFT SECURITY
DESCRIPTION
DESCRIPTION - VEHICLE THEFT
SECURITY SYSTEM....................1
DESCRIPTION - SENTRY KEY
IMMOBILIZER SYSTEM..................2
OPERATION
OPERATION - VEHICLE THEFT SECURITY
SYSTEM.............................2
OPERATION - SENTRY KEY IMMOBILIZER
SYSTEM.............................4
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VEHICLE
THEFT SECURITY SYSTEM..............4
DIAGNOSIS AND TESTING - SENTRY KEY
IMMOBILIZER SYSTEM..................5
STANDARD PROCEDURE
STANDARD PROCEDURE - SKIS
INITIALIZATION........................6
STANDARD PROCEDURE - SENTRY KEY
TRANSPONDER PROGRAMMING..........6
DOOR CYLINDER LOCK SWITCH
DESCRIPTION..........................7
OPERATION............................8
DIAGNOSIS AND TESTING - DOOR
CYLINDER LOCK SWITCH...............8
REMOVAL.............................8
INSTALLATION..........................9
HOOD AJAR SWITCH
DESCRIPTION..........................9
OPERATION............................9
DIAGNOSIS AND TESTING - HOOD AJAR
SWITCH.............................9REMOVAL
REMOVAL - HOOD AJAR SWITCH........10
REMOVAL - HOOD AJAR SWITCH
BRACKET...........................10
REMOVAL - HOOD AJAR SWITCH STRIKER . 10
INSTALLATION
INSTALLATION - HOOD AJAR SWITCH.....10
INSTALLATION - HOOD AJAR SWITCH
BRACKET...........................10
INSTALLATION - HOOD AJAR SWITCH
STRIKER............................11
INTRUSION TRANSCEIVER MODULE
DESCRIPTION.........................11
OPERATION...........................11
REMOVAL.............................12
INSTALLATION.........................12
SIREN
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................14
INSTALLATION.........................14
SKIS INDICATOR LAMP
DESCRIPTION.........................14
OPERATION...........................14
TRANSPONDER KEY
DESCRIPTION.........................15
OPERATION...........................15
VTSS INDICATOR
DESCRIPTION.........................15
OPERATION...........................16
DIAGNOSIS AND TESTING - VTSS
INDICATOR..........................16
VEHICLE THEFT SECURITY
DESCRIPTION
DESCRIPTION - VEHICLE THEFT SECURITY
SYSTEM
The Vehicle Theft Security System (VTSS) is
designed to provide perimeter protection against
unauthorized vehicle use or tampering by monitoring
the vehicle doors, the liftgate, the liftgate flip-up
glass, the ignition system and, only on vehicles built
for sale in certain international markets where it is
required equipment, the hood. If unauthorized vehi-cle use or tampering is detected, the system responds
by pulsing the horn and flashing the exterior lamps.
In many markets the VTSS also includes the Sentry
Key Immobilizer System (SKIS), which provides pas-
sive vehicle protection by preventing the engine from
operating unless a valid electronically encoded key is
detected in the ignition lock cylinder. (Refer to 8 -
ELECTRICAL/VEHICLE THEFT SECURITY -
DESCRIPTION - SENTRY KEY IMMOBILIZER
SYSTEM).
The VTSS includes the following major compo-
nents, which are described in further detail else-
where in this service manual:
²Body Control Module (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/BODY
WJVEHICLE THEFT SECURITY 8Q - 1

CONTROL/CENTRAL TIMER MODULE -
DESCRIPTION).
²Combination Flasher (Refer to 8 - ELECTRI-
CAL/LAMPS/LIGHTING - EXTERIOR/COMBINA-
TION FLASHER - DESCRIPTION).
²Door Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - DOOR AJAR SWITCH).
²Driver Cylinder Lock Switch (Refer to 8 - ELEC-
TRICAL/POWER LOCKS/DOOR CYLINDER LOCK/
UNLOCK SWITCH - DESCRIPTION).
²Hood Ajar Switch(Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/HOOD AJAR SWITCH -
DESCRIPTION).
²Horn Relay (Refer to 8 - ELECTRICAL/HORN/
HORN RELAY - DESCRIPTION).
²Liftgate Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - LIFTGATE AJAR
SWITCH).
²Liftgate Flip-Up Glass Ajar Switch(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - INTERIOR/
DOOR AJAR SWITCH - DESCRIPTION - LIFTGATE
FLIP-UP GLASS AJAR SWITCH).
²Low Beam Headlamp Relay
²VTSS Indicator (Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/VTSS INDICATOR -
DESCRIPTION).
Certain functions and features of the VTSS rely
upon resources shared with or controlled by other
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. The
other modules that may affect VTSS operation are:
²Driver Door Module (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DOOR MOD-
ULE - DESCRIPTION).
²Passenger Door Module (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/DOOR
MODULE - DESCRIPTION).
DESCRIPTION - SENTRY KEY IMMOBILIZER
SYSTEM
Vehicles equipped with the Sentry Key Immobilizer
System (SKIS) can be identified by the presence of
an amber SKIS indicator in the instrument cluster
that will illuminate for about three seconds each
time the ignition switch is turned to the On position,
or by a gray molded rubber cap on the head of the
ignition key. Models not equipped with SKIS still
have a SKIS indicator in the cluster, but it will not
illuminate. Also, models not equipped with the SKIS
have a black molded rubber cap on the head of the
ignition key.
The SKIS includes the following major components,
which are described in further detail elsewhere in
this service manual:²Powertrain Control Module
²Sentry Key Immobilizer Module
²Sentry Key Transponder
²SKIS Indicator
Except for the Sentry Key transponders, which rely
upon Radio Frequency (RF) communication, hard
wired circuitry connects the SKIS components to the
electrical system of the vehicle.Refer to the appropri-
ate wiring information.
OPERATION
OPERATION - VEHICLE THEFT SECURITY
SYSTEM
The Vehicle Theft Security System (VTSS) is
divided into two basic subsystems: Vehicle Theft
Alarm (VTA) and Sentry Key Immobilizer System
(SKIS). The following are paragraphs that briefly
describe the operation of each of those two sub-
systems.
A Body Control Module (BCM) is used to control
and integrate many of the functions and features
included in the Vehicle Theft Security System
(VTSS). In the VTSS, the BCM receives inputs indi-
cating the status of the door ajar switches, the driver
cylinder lock switch, the ignition switch, the liftgate
ajar switches, the liftgate flip-up glass ajar switch,
the power lock switches and, in vehicles so equipped,
the hood ajar switch. The programming in the BCM
allows it to process the information from all of these
inputs and send control outputs to energize or de-en-
ergize the combination flasher, the horn relay (except
vehicles with the premium version of the VTA), and
the VTSS indicator. In addition, in vehicles built for
certain markets where premium versions of the VTA
is required, the BCM also exchanges messages with
the Intrusion Transceiver Module (ITM) over the Pro-
grammable Communications Interface (PCI) data
buss network to provide the features found in this
version of the VTA. The control of these inputs and
outputs are what constitute all of the features of the
VTSS. Following is information on the operation of
each of the VTSS features.
ENABLING
The BCM must have the VTSS function enabled in
order for the VTSS to perform as designed. The logic
in the BCM keeps its VTSS function dormant until it
is enabled using a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
PRE-ARMING
The VTA has a pre-arming sequence. Pre-arming
occurs when a door, the tailgate, or the flip-up glass
is open when the vehicle is locked using a power lock
8Q - 2 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)

tion feature of the ITM can be disabled by depressing
the ªLockº button on the RKE transmitter three
times or cycling the key in the driver door cylinder
from the center to lock position within fifteen seconds
during VTA arming, while the security indicator is
still flashing rapidly. The VTA provides a single short
siren ªchirpº as an audible conformation that the
motion detect disable request has been received. The
ITM must be electronically enabled in order for the
intrusion alarm to perform as designed. The intru-
sion alarm function of the ITM is enabled on vehicles
equipped with this option at the factory, but a service
replacement ITM must be configured and enabled by
the dealer using the DRBIIItscan tool. Refer to the
appropriate diagnostic information.
OPERATION - SENTRY KEY IMMOBILIZER
SYSTEM
The Sentry Key Immobilizer System (SKIS) is
designed to provide passive protection against unau-
thorized vehicle use by disabling the engine after
about two seconds of running, whenever any method
other than a valid Sentry Key is used to start the
vehicle. The SKIS is considered a passive protection
system because it is always active when the ignition
system is energized and does not require any cus-
tomer intervention. The SKIS uses Radio Frequency
(RF) communication to obtain confirmation that the
key in the ignition switch is a valid key for operating
the vehicle. The microprocessor-based SKIS hard-
ware and software also uses messages to communi-
cate with other modules in the vehicle over the
Programmable Communications Interface (PCI) data
bus. (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/COMMUNICATION - OPERA-
TION).
Pre-programmed Sentry Key transponders are pro-
vided with the vehicle from the factory. Each Sentry
Key Immobilizer Module (SKIM) will recognize a
maximum of eight Sentry Keys. If the customer
would like additional keys other than those provided
with the vehicle, they may be purchased from any
authorized dealer. These additional keys must be pro-
grammed to the SKIM in the vehicle in order for the
system to recognize them as valid keys. This can be
done by the dealer using a DRBIIItscan tool or, if
Customer Learn programming is an available SKIS
feature in the market where the vehicle was pur-
chased, the customer can program the additional
keys, as long as at least two valid Sentry Keys are
already available. (Refer to 8 - ELECTRICAL/VEHI-
CLE THEFT SECURITY - STANDARD PROCE-
DURE - TRANSPONDER PROGRAMMING).
The SKIS performs a self-test each time the igni-
tion switch is turned to the On position, and will
store fault information in the form of DiagnosticTrouble Codes (DTC's) if a system malfunction is
detected. Refer to the appropriate diagnostic informa-
tion.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VEHICLE THEFT
SECURITY SYSTEM
The VTSS-related hard wired inputs to and out-
puts from the Body Control Module (BCM), the
Driver Door Module (DDM), or the Passenger Door
Module (PDM) may be diagnosed and tested using
conventional diagnostic tools and procedures. Refer
to the appropriate wiring information.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the BCM, the
DDM, the PDM, or the Programmable Communica-
tions Interface (PCI) data bus network. In order to
obtain conclusive testing of the VTSS, the BCM, the
DDM, the PDM, and the PCI data bus network must
also be checked. The most reliable, efficient, and
accurate means to diagnose the VTSS requires the
use of a DRBIIItscan tool and the appropriate diag-
nostic information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
8Q - 4 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)