JEEP LIBERTY 2002 KJ / 1.G Workshop Manual

Theft Security System (VTSS) have a door cylinder
lock switch secured to the back of the key lock cylin-
der inside each front door (Fig. 2). The door cylinder
lock switch is a resistor multiplexed momentary
switch that is hard wired in series between the door
lock switch ground and right or left cylinder lock
switch mux circuits of the Body Control Module
(BCM) through the front door wire harness. The door
cylinder lock switches are driven by the key lock cyl-
inders and contain two internal resistors. One resis-
tor value is used for the Lock position, and one for
the Unlock position.
The door cylinder lock switches cannot be adjusted
or repaired and, if faulty or damaged, they must be
replaced.
OPERATION
The door cylinder lock switches are actuated by the
key lock cylinder when the key is inserted in the lock
cylinder and turned to the lock or unlock positions.
The door cylinder lock switch close a circuit between
the door lock switch ground circuit and the left or
right cylinder lock switch mux circuits through one of
two internal resistors for the Body Control Module
(BCM) when either front door key lock cylinder is in
the Lock, or Unlock positions. The BCM reads the
switch status through an internal pull-up, then uses
this information as an input for the Vehicle Theft
Security System (VTSS) operation.
The door cylinder lock switches and circuits can be
diagnosed using conventional diagnostic tools and
methods.
DIAGNOSIS AND TESTING - DOOR CYLINDER
LOCK SWITCH
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices and grounds.
(1) Disconnect the door cylinder lock switch pigtail
wire connector from the door wire harness connector.
(2) Using a ohmmeter, check the switch resistance
checks between the two terminals in the door cylin-
der lock switch pigtail wire connector. Actuate the
switch by rotating the key in the door lock cylinder
to test for the proper resistance values in each of the
two switch positions, as shown in the Door Cylinder
Lock Switch Test table.
DOOR CYLINDER LOCK SWITCH TEST
Switch Position Resistance
( 10%)
Left Side Right Side
Lock (Clockwise) Unlock
(Counterclockwise)473 Ohms
Unlock
(Counterclockwise)Lock (Clockwise) 1.994 Kilohms
(3) If a door cylinder lock switch fails either of the
resistance tests, replace the faulty switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the outside door handle unit from the
outer door panel. (Refer to 23 - BODY/DOOR -
FRONT/EXTERIOR HANDLE - REMOVAL).
(3) Remove the retainer clip from the pin on the
back of the door lock cylinder (Fig. 3).
(4) Remove the lock lever from the pin on the back
of the door lock cylinder.
(5) Remove the door cylinder lock switch from the
back of the lock cylinder.
INSTALLATION
(1) Position the door cylinder lock switch onto the
back of the lock cylinder with its pigtail wire harness
oriented toward the bottom (Fig. 3).
Fig. 3 Lock Cylinder Lever Retainer Remove/Install
1 - LEVER
2 - RETAINER
3 - LOCK CYLINDER
4 - SWITCH
5 - PLIERS
6 - OUTSIDE DOOR HANDLE
8Q - 10 VEHICLE THEFT SECURITYKJ
DOOR CYLINDER LOCK SWITCH (Continued)

(2) Position the lock lever onto the pin on the back
of the door lock cylinder with the lever oriented
toward the rear.
(3) Install the retainer clip onto the pin on the
back of the door lock cylinder. Be certain that the
center tab of the retainer is engaged in the retention
hole on the lock lever.
(4) Reinstall the outside door handle unit onto the
outer door panel. (Refer to 23 - BODY/DOOR -
FRONT/EXTERIOR HANDLE - INSTALLATION).
(5) Reconnect the battery negative cable.
HOOD AJAR SWITCH
DESCRIPTION
The hood ajar switch is a normally closed, single
pole momentary switch that is used only on vehicles
equipped with the Vehicle Theft Security System
(VTSS) for sale in certain markets where it is
required equipment (Fig. 4). This switch consists of a
molded plastic body with a molded plastic mounting
bezel. The switch body has an integral molded con-nector receptacle on the lower end, while the spring-
loaded switch plunger extends from the upper end.
Two external latches integral to the mounting bezel
lock the switch into a keyed mounting hole in the
stamped steel switch mounting bracket. The mount-
ing bracket is fastened with two screws to the right
inner fender shield near the fender ledge in the
engine compartment. A molded plastic striker with
an integral retainer and mounting tab is secured to
the underside of the hood panel inner reinforcement
to actuate the switch plunger as the hood panel is
closed (Fig. 5). A single take out of the headlamp and
dash wire harness connects the switch to the vehicle
electrical system. The switch receives a path to
ground at all times through another take out of the
headlamp and dash wire harness with an eyelet ter-
minal connector that is secured by a ground screw to
the left inner fender shield in the engine compart-
ment.
The hood ajar switch cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced. The hood ajar switch striker is not intended
for reuse. If the striker is removed from the hood
inner reinforcement for any reason, it must be
replaced with a new unit.
Fig. 4 Hood Ajar Switch
1 - INNER FENDER
2 - SCREW (2)
3 - BRACKET
4 - HOOD AJAR SWITCH
5 - WIRE HARNESS CONNECTOR
Fig. 5 Hood Ajar Switch Striker
1 - STRIKER
2-TAB
3 - INNER HOOD REINFORCEMENT
4 - RETAINER
KJVEHICLE THEFT SECURITY 8Q - 11
DOOR CYLINDER LOCK SWITCH (Continued)

OPERATION
The hood ajar switch is normally held open as the
spring-loaded switch plunger is depressed by the
striker on the hood panel when the hood panel is
closed and latched. When the hood is opened, the
spring-loaded switch plunger extends from the switch
body and the switch contacts are closed. The hood
ajar switch is connected in series between ground
and the hood ajar switch sense input of the Body
Control Module (BCM). The BCM uses an internal
resistor pull up to monitor the state of the hood ajar
switch contacts. The hood ajar switch can be diag-
nosed using conventional diagnostic tools and meth-
ods.
DIAGNOSIS AND TESTING - HOOD AJAR
SWITCH
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
(1) Disconnect the headlamp and dash wire har-
ness connector for the hood ajar switch from the
switch connector receptacle.
(2) Check for continuity between the two terminals
in the connector receptacle of the hood ajar switch.
There should be continuity with the switch plunger
extended, and no continuity with the switch plunger
depressed. If not OK, replace the faulty hood ajar
switch.
REMOVAL
(1) Unlatch and open the hood.
(2) Disconnect and isolate the battery negative
cable.
(3) From the top of the hood ajar switch mounting
bracket, squeeze the two switch latch tabs together
and pull the switch upward (Fig. 6).
(4) Pull the hood ajar switch up through the hole
in the mounting bracket far enough to access and
disconnect the headlamp and dash wire harness con-
nector for the hood ajar switch from the switch con-
nector receptacle.(5) Remove the hood ajar switch from the mount-
ing bracket.
INSTALLATION
(1) Position the hood ajar switch near the hole in
the mounting bracket (Fig. 6).
(2) Reconnect the headlamp and dash wire harness
connector for the hood ajar switch to the switch con-
nector receptacle.
(3) From the top of the hood ajar switch mounting
bracket, use hand pressure to press the switch down-
ward into the mounting bracket until the latch tabs
lock it into place.
(4) Reconnect the battery negative cable.
(5) Close and latch the hood.
Fig. 6 Hood Ajar Switch Remove/Install
1 - INNER FENDER
2 - SCREW (2)
3 - BRACKET
4 - HOOD AJAR SWITCH
5 - WIRE HARNESS CONNECTOR
8Q - 12 VEHICLE THEFT SECURITYKJ
HOOD AJAR SWITCH (Continued)

HOOD AJAR SWITCH
BRACKET
REMOVAL
(1) Remove the hood ajar switch from the mount-
ing bracket. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY/HOOD AJAR SWITCH -
REMOVAL).
(2) If necessary, remove and set aside the engine
air cleaner housing for access to the hood ajar switch
mounting bracket screws.
(3) Remove the two screws that secure the hood
ajar switch bracket to the right fender inner shield
(Fig. 7).
(4) Remove the hood ajar switch bracket from the
right fender inner shield.
INSTALLATION
(1) Position the hood ajar switch bracket onto the
right fender inner shield (Fig. 7).
(2) Install and tighten the two screws that secure
the hood ajar switch bracket to the right fender inner
shield. Tighten the screws to 7 N´m (60 in. lbs.).
(3) If removed, reinstall the engine air cleaner
housing.(4) Reinstall the hood ajar switch into the mount-
ing bracket. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY/HOOD AJAR SWITCH -
INSTALLATION).
HOOD AJAR SWITCH STRIKER
REMOVAL
The hood ajar switch striker is not intended for
reuse. If the striker is removed from the hood inner
reinforcement for any reason, it must be replaced
with a new unit.
(1) Unlatch and open the hood.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the rearward end of the
hood ajar switch striker away from the inner hood
panel reinforcement far enough to disengage the inte-
gral retainer from its mounting hole (Fig. 8).
(3) Move the hood ajar switch striker slightly rear-
ward to disengage the integral mounting tab from
the forward mounting hole.
(4) Remove the hood ajar switch striker from the
inner hood panel reinforcement and discard.
Fig. 7 Hood Ajar Switch Bracket Remove/Install
1 - INNER FENDER
2 - SCREW (2)
3 - BRACKET
4 - HOOD AJAR SWITCH
5 - WIRE HARNESS CONNECTOR
Fig. 8 Hood Ajar Switch Striker Remove/Install
1 - STRIKER
2-TAB
3 - INNER HOOD REINFORCEMENT
4 - RETAINER
KJVEHICLE THEFT SECURITY 8Q - 13

INSTALLATION
The hood ajar switch striker is not intended for
reuse. If the striker is removed from the hood inner
reinforcement for any reason, it must be replaced
with a new unit.
(1) Position the new hood ajar switch striker to the
inner hood panel reinforcement (Fig. 8).
(2) Insert the integral mounting tab on the front of
the hood ajar switch striker into the forward mount-
ing hole in the inner hood panel reinforcement.
(3) Align the integral retainer on the rear of the
hood ajar switch striker with the rearward mounting
hole in the inner hood panel reinforcement.
(4) Using hand pressure, firmly press the hood
ajar switch striker rearward and upward against the
inner hood panel reinforcement until the hood ajar
switch striker retainer is fully engaged in the rear-
ward mounting hole in the inner hood panel rein-
forcement.
(5) Close and latch the hood.
INTRUSION TRANSCEIVER
MODULE
DESCRIPTION
An Intrusion Transceiver Module (ITM) is part of
the Rest-Of-World (ROW) premium version of the
Vehicle Theft Alarm (VTA) in the Vehicle Theft Secu-
rity System (VTSS) (Fig. 9). The ROW premium ver-
sion of the VTA is only available in vehicles built for
certain markets, where the additional features
offered by this system are required. The ITM is
located in the passenger compartment, on the lower
surface of the headliner near the center of the vehi-cle. This unit is designed to provide interior motion
detection, and serve as an interface between the
Body Control Module (BCM) and the alarm siren
module.
The ITM is concealed beneath a dedicated molded
plastic trim cover that approximates the size and
shape of a typical dome lamp housing. However,
rather than a lens, the ITM features three sets of
louvered openings in a molded lateral center rib for-
mation. One set of louvered openings is located at
each outboard end of the center rib, while the third
set is centered. Each of the louvered openings is cov-
ered on the inside by a single molded black plastic
sight shield that extends the length of the center rib
for appearance. The module is secured to a molded
plastic mounting bracket above the headliner by four
latch features that are integral to the underside of
the module housing. Besides the ITM, the trim cover
also conceals two plastic pins integral to the mount-
ing bracket that are used to secure the bracket to the
headliner with two stamped nuts that are installed
from below. An adhesive-backed foam pad is installed
above the ITM bracket between the headliner and
the roof panel to provide additional headliner stabili-
zation and support for the ITM mounting. Two small
notch-like service holes on the rear edge of the trim
cover afford access to the two integral rear latches of
the ITM for service removal (Fig. 10).
The ITM circuitry is contained within a black
molded plastic housing with four integral mounting
tabs that are secured to the back of the trim cover
with four screws. Concealed within the housing is the
Fig. 9 Intrusion Transceiver Module
1 - ITM
2 - HEADLINERFig. 10 Intrusion Transceiver Module
1 - TRIM COVER
2 - CONNECTOR RECEPTACLE
3 - HOUSING
4 - SCREW (4)
5 - SERVICE HOLE (2)
6 - LATCH FEATURE (4)
8Q - 14 VEHICLE THEFT SECURITYKJ
HOOD AJAR SWITCH STRIKER (Continued)

electronic circuitry of the ITM which includes a
microprocessor, and an ultrasonic receive transducer.
A molded plastic connector receptacle containing six
terminal pins that is soldered to a small circuit board
and extends through a clearance hole in the left front
corner of the ITM housing, and an ultrasonic trans-
mit transducer housing extends from the center of
the right side of the ITM housing. Both the transmit
transducer on the right side of the module and the
receive transducer on the ITM circuit board are
aimed through two small round holes in the sight
shield of the trim cover. The ITM is connected to the
vehicle electrical system by a dedicated take out and
connector of the overhead wire harness that is inte-
gral to the headliner.
The ITM unit cannot be adjusted or repaired and,
if faulty or damaged, it must be replaced. The ITM is
serviced as a unit with the trim cover.
OPERATION
The microprocessor in the Intrusion Transceiver
Module (ITM) contains the motion sensor logic cir-
cuits and controls all of the features of the premium
version of the Vehicle Theft Alarm (VTA). The ITM
uses On-Board Diagnostics (OBD) and can communi-
cate with other electronic modules in the vehicle as
well as with the DRBIIItscan tool using the Pro-
grammable Communications Interface (PCI) data bus
network. This method of communication is used by
the ITM to communicate with the Body Control Mod-
ule (BCM) and for diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. The ITM also
communicates with the alarm siren over a dedicated
serial bus circuit.
The ITM microprocessor continuously monitors
inputs from its on-board motion sensor circuitry as
well as inputs from the BCM and the alarm siren
module. The on-board ITM motion sensor circuitry
transmits ultrasonic signals into the vehicle cabin
through a transmit transducer, then listens to the
returning signals as the bounce off of objects in the
vehicle interior. If an object is moving in the interior,
a detection circuit in the ITM senses this movement
through the modulation of the returning ultrasonic
signals that occurs due to the Doppler effect. The
motion detect function of the ITM can be disabled by
depressing the ªLockº button on the Remote Keyless
Entry (RKE) transmitter three times within fifteen
seconds, while the security indicator is still flashing
rapidly. The ITM will signal the alarm siren module
to provide a single siren ªchirpº as an audible confir-
mation that the motion sensor function has been dis-
abled.
If movement is detected, the ITM sends an elec-
tronic message to the BCM over the PCI data bus toflash the exterior lighting and sends an electronic
message to the alarm siren module over a dedicated
serial bus line to sound the siren. When the BCM
detects a breach in the perimeter protection through
a door, tailgate, flip-up glass, or hood ajar switch
input, it sends an electronic message to the ITM and
the ITM sends an electronic message to the BCM
over the PCI data bus to flash the exterior lighting
and sends an electronic message to the alarm siren
module over a dedicated serial bus line to sound the
siren. The ITM also monitors inputs from the alarm
siren module for siren battery or siren input/output
circuit tamper alerts, and siren battery condition
alerts, then sets active and stored Diagnostic Trouble
Codes (DTC) for any monitored system faults it
detects. An active fault only remains for the current
ignition switch cycle, while a stored fault causes a
DTC to be stored in memory by the ITM. If a fault
does not recur for fifty ignition cycles, the ITM will
automatically erase the stored DTC.
The ITM is connected to the vehicle electrical sys-
tem through a dedicated take out and connector of
the overhead wire harness. The ITM receives battery
current on a fused B(+) circuit through a fuse in the
Junction Block (JB), and receives ground through a
ground circuit and take out of the body wire harness.
This ground take out has a single eyelet terminal
connector that is secured by a ground screw to the
base of the left D-pillar behind the quarter trim
panel. These connections allow the ITM to remain
operational, regardless of the ignition switch position.
The hard wired inputs and outputs for the ITM may
be diagnosed and tested using conventional diagnos-
tic tools and procedures. However, conventional diag-
nostic methods will not prove conclusive in the
diagnosis of the ITM, the PCI data bus network, or
the electronic message inputs to and outputs from
the ITM. The most reliable, efficient, and accurate
means to diagnose the ITM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ITM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) While pulling downward lightly on either rear
corner of the Intrusion Transceiver Module (ITM)
trim cover, insert a small thin-bladed screwdriver
through each of the service holes on the rear edge of
the trim cover to depress and release the two inte-
gral rear latch features of the module from the
mounting bracket above the headliner (Fig. 11).
(3) Pull the ITM trim cover rearward far enough
to disengage the two integral front latch features of
KJVEHICLE THEFT SECURITY 8Q - 15
INTRUSION TRANSCEIVER MODULE (Continued)

the module from the mounting bracket above the
headliner.
(4) Pull the ITM and trim cover down from the
headliner far enough to access and disconnect the
overhead wire harness connector for the ITM from
the module connector receptacle.
(5) Remove the ITM from the headliner.
INSTALLATION
(1) Position the Intrusion Transceiver Module
(ITM) to the headliner.
(2) Reconnect the overhead wire harness connector
for the ITM to the module connector receptacle.
(3) Align the two integral front latch features of
the ITM with the two front latch receptacles of the
mounting bracket above the headliner (Fig. 12).
(4) Push the ITM trim cover forward far enough to
insert the two integral rear latch features of the
module into the two rear latch receptacles of the
mounting bracket above the headliner.
(5) Push upward firmly and evenly on the rear
edge of the ITM trim cover until the two integral
rear latch features of the module are engaged in the
latch receptacles of the mounting bracket above the
headliner.
(6) Reconnect the battery negative cable.
NOTE: If the Intrusion Transceiver Module (ITM) has
been replaced with a new unit, the new ITM MUST
be initialized before the Vehicle Theft Security Sys-
tem can operate as designed. The use of a DRBIIIT
scan tool is required to initialize the ITM. Refer to
the appropriate diagnostic information.
SIREN
DESCRIPTION
An alarm siren module is part of the Rest-Of-World
(ROW) premium version of the Vehicle Theft Alarm
(VTA) in the Vehicle Theft Security System (VTSS)
(Fig. 13). The ROW premium version of the VTA is
only available in vehicles built for certain markets,
where the additional features offered by this system
are required. The alarm siren module is located in
Fig. 11 Intrusion Transceiver Module Remove
1 - SMALL SCREWDRIVER
2 - HEADLINER
3 - SERVICE HOLES
4 - ITM
Fig. 12 Intrusion Transceiver Module Mounting
Bracket
1 - STAMPED NUT (2)
2 - MOUNTING BRACKET
3 - HEADLINER
4 - LATCH RECEPTACLES (4)
Fig. 13 Siren Module
1 - BRACKET
2 - NUT (3)
3 - CONNECTOR RECEPTACLE
4 - SIREN MODULE
8Q - 16 VEHICLE THEFT SECURITYKJ
INTRUSION TRANSCEIVER MODULE (Continued)

the engine compartment, on the front extension of
the right front wheel house panel below and behind
the right headlamp. This unit is designed to provide
the audible alert requirements for the ROW premium
VTA.
The alarm siren module consists of microprocessor-
based electronic control circuitry, the siren, and a
nickel metal hydride backup battery. All of the alarm
module components are protected and sealed within
a black molded plastic housing. A stamped steel
mounting bracket is secured to the module with
three stud plates and nuts that fit into slotted holes
at the top and each side of the bracket. The front
surface of the bracket features a tightly grouped
series of small holes that serves as an outlet for the
audible output of the alarm siren. The bottom of the
mounting bracket is bent at a right angle and has an
integral locating tab feature. Two mounting holes in
the horizontal surface of the bracket are used to
secure the alarm siren module to the wheel house
extension with two screws. An integral connector
receptacle extends forward from the upper left corner
of the alarm siren housing, and connects the unit to
the vehicle electrical system through a dedicated
take out and connector of the headlamp and dash
wire harness.
The alarm siren module cannot be repaired or
adjusted and, if faulty or damaged, it must be
replaced.
OPERATION
The microprocessor within the alarm siren module
performs the tasks required to provide the siren unit
features and functions based upon internal program-
ming and electronic arm and disarm message inputs
received from the Intrusion Transceiver Module
(ITM) over a dedicated serial bus communication cir-
cuit. The alarm siren module will self-detect prob-
lems with its internal and external power supply and
communication circuits, then send electronic mes-
sages indicating the problem to the ITM upon receiv-
ing a request from the ITM. The ITM will store a
Diagnostic Trouble Code (DTC) for a detected alarm
siren module fault that can be retrieved with the
DRBIIItscan tool over the Programmable Communi-
cations Interface (PCI) data bus network through the
16-way data link connector located on the driver side
lower edge of the instrument panel.
When the Rest-Of-World (ROW) premium version
of the Vehicle Theft Alarm (VTA) is armed, the alarm
siren module microprocessor continuously monitors
inputs from the ITM for messages to sound its inter-
nal siren and enters its auto-detect mode. While in
the auto-detect mode, if the alarm siren module
detects that its power supply or communication cir-
cuits are being tampered with or have been sabo-taged, it will sound an alarm and continue to operate
through its on-board backup battery. If the arm siren
module is in its disarmed mode when its power sup-
ply or communication circuits are interrupted, the
siren will not sound. The alarm module will also
notify the ITM when the backup battery requires
charging, and the ITM will send a message that will
allow the backup battery to be charged through the
battery current and ground circuits to the alarm
module only when the ignition switch is in the On
position and the engine is running. This will prevent
the charging of the alarm backup battery from
depleting the charge in the main vehicle battery
while the vehicle is not being operated.
The alarm siren module receives battery current
on a fused B(+) circuit through a fuse in the Power
Distribution Center (PDC), and receives ground
through a ground circuit and take out of the head-
lamp and dash wire harness. This ground take out
has a single eyelet terminal connector that is secured
by a ground screw to the left inner fender shield in
the engine compartment. These connections allow the
alarm siren module to remain operational, regardless
of the ignition switch position. The hard wired inputs
and outputs for the alarm siren module may be diag-
nosed and tested using conventional diagnostic tools
and procedures. However, conventional diagnostic
methods will not prove conclusive in the diagnosis of
the internal circuitry or the backup battery of the
alarm siren module, the ITM, the serial bus commu-
nication line, or the electronic message inputs to and
outputs from the alarm siren module. The most reli-
able, efficient, and accurate means to diagnose the
alarm siren module, the ITM, the serial bus commu-
nication line, and the electronic message inputs to
and outputs from the alarm siren module requires
the use of a DRBIIItscan tool. Refer to the appro-
priate diagnostic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the headlamp and dash wire har-
ness connector for the alarm siren module from the
module connector receptacle (Fig. 14).
(3) Remove the two screws that secure the alarm
siren module to the front extension of the right front
wheel house panel.
(4) Remove the alarm siren module from the front
extension of the right front wheel house panel.
INSTALLATION
(1) Position the alarm siren module onto the front
extension of the right front wheel house panel (Fig.
14).
KJVEHICLE THEFT SECURITY 8Q - 17
SIREN (Continued)

(2) Install and tighten the two screws that secure
the alarm siren module to the front extension of the
right front wheel house panel. Tighten the screws to
6 N´m (50 in. lbs.).
(3) Reconnect the headlamp and dash wire harness
connector for the alarm siren module to the module
connector receptacle.
(4) Reconnect the battery negative cable.
NOTE: If the alarm siren module has been replaced
with a new unit, the new unit MUST be configured
in the Intrusion Transceiver Module (ITM) before the
Vehicle Theft Security System can operate as
designed. The use of a DRBIIITscan tool is required
to configure the alarm siren module settings in the
ITM. Refer to the appropriate diagnostic informa-
tion.
TRANSPONDER KEY
DESCRIPTION
Each ignition key used in the Sentry Key Immobi-
lizer System (SKIS) has an integral transponder chip
(Fig. 15). Ignition keys with this feature can be
readily identified by a gray rubber cap molded onto
the head of the key, while conventional ignition keys
have a black molded rubber cap. The transponderchip is concealed beneath the molded rubber cap,
where it is molded within a plastic mount into the
head of the metal key. In addition to being cut to
match the mechanical coding of the ignition lock cyl-
inder, each new Sentry Key has a unique transpon-
der identification code permanently programmed into
it by the manufacturer. The Sentry Key transponder
cannot be adjusted or repaired. If faulty or damaged,
the entire key must be replaced.
OPERATION
When the ignition switch is turned to the On posi-
tion, the Sentry Key Immobilizer Module (SKIM)
communicates through its antenna with the Sentry
Key transponder using a Radio Frequency (RF) sig-
nal. The SKIM then listens for a RF response from
the transponder through the same antenna. The Sen-
try Key transponder chip is within the range of the
SKIM transceiver antenna ring when it is inserted
into the ignition lock cylinder. The SKIM determines
whether a valid key is present in the ignition lock
cylinder based upon the response from the transpon-
der. If a valid key is detected, that fact is communi-
cated by the SKIM to the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus, and the PCM allows the
engine to continue running. If the PCM receives an
invalid key message, or receives no message from the
SKIM over the PCI data bus, the engine will be dis-
abled after about two seconds of operation. The Elec-
troMechanical Instrument Cluster (EMIC) will also
respond to the invalid key message on the PCI data
bus by flashing the SKIS indicator on and off.
Fig. 14 Siren Remove/Install
1 - SCREW (2)
2 - WIRE HARNESS CONNECTOR
3 - SIREN
Fig. 15 Sentry Key Immobilizer Transponder
1 - MOLDED CAP
2 - TRANSPONDER CHIP
3 - MOLDED CAP REMOVED
4 - TRANSPONDER KEY
8Q - 18 VEHICLE THEFT SECURITYKJ
SIREN (Continued)

Each Sentry Key has a unique transponder identi-
fication code permanently programmed into it by the
manufacturer. Likewise, the SKIM has a unique
Secret Key code programmed into it by the manufac-
turer. When a Sentry Key is programmed into the
memory of the SKIM, the SKIM stores the transpon-
der identification code from the Sentry Key, and the
Sentry Key learns the Secret Key code from the
SKIM. Once the Sentry Key learns the Secret Key
code of the SKIM, it is permanently stored in the
memory of the transponder. Therefore, once a Sentry
Key has been programmed to a particular vehicle, it
cannot be used on any other vehicle. (Refer to 8 -ELECTRICAL/VEHICLE THEFT SECURITY -
STANDARD PROCEDURE - TRANSPONDER PRO-
GRAMMING).
The SKIS performs a self-test each time the igni-
tion switch is turned to the On position, and will
store key-related fault information in the form of
Diagnostic Trouble Codes (DTC's) in SKIM memory if
a Sentry Key transponder problem is detected. The
Sentry Key transponder chip can be diagnosed, and
any stored DTC's can be retrieved using a DRBIIIt
scan tool. Refer to the appropriate diagnostic
information.
KJVEHICLE THEFT SECURITY 8Q - 19
TRANSPONDER KEY (Continued)