2002 JEEP LIBERTY Electrical

VEHICLE THEFT SECURITY
TABLE OF CONTENTS
page page
VEHICLE THEFT SECURITY
DESCRIPTION..........................1
OPERATION............................3
DIAGNOSIS AND TESTING - VEHICLE THEFT
SECURITY SYSTEM....................6
STANDARD PROCEDURE
STANDARD PROCEDURE - SKIS
INITIALIZATION........................8
STANDARD PROCEDURE - SENTRY KEY
TRANSPONDER PROGRAMMING..........8
DOOR CYLINDER LOCK SWITCH
DESCRIPTION..........................9
OPERATION...........................10
DIAGNOSIS AND TESTING - DOOR
CYLINDER LOCK SWITCH..............10
REMOVAL.............................10
INSTALLATION.........................10
HOOD AJAR SWITCH
DESCRIPTION.........................11
OPERATION...........................12
DIAGNOSIS AND TESTING - HOOD AJAR
SWITCH............................12REMOVAL.............................12
INSTALLATION.........................12
HOOD AJAR SWITCH BRACKET
REMOVAL.............................13
INSTALLATION.........................13
HOOD AJAR SWITCH STRIKER
REMOVAL.............................13
INSTALLATION.........................14
INTRUSION TRANSCEIVER MODULE
DESCRIPTION.........................14
OPERATION...........................15
REMOVAL.............................15
INSTALLATION.........................16
SIREN
DESCRIPTION.........................16
OPERATION...........................17
REMOVAL.............................17
INSTALLATION.........................17
TRANSPONDER KEY
DESCRIPTION.........................18
OPERATION...........................18
VEHICLE THEFT SECURITY
DESCRIPTION
The Vehicle Theft Security System (VTSS) is an
available factory-installed option on this model (Fig.
1). The VTSS is comprised of two primary sub-
systems: Vehicle Theft Alarm (VTA) and Sentry Key
Immobilizer System (SKIS). The VTA is an active
system that provides visual and audible responses as
deterrents to and warnings of unauthorized vehicle
tampering. The SKIS is a passive system that effec-
tively immobilizes the vehicle against unauthorized
operation. Following are paragraphs which describe
the various components that are included in each of
these subsystems of the VTSS.
Hard wired circuitry connects many of the VTSS
components to each other through the electrical sys-
tem of the vehicle. These hard wired circuits are
integral to several wire harnesses, which are routed
throughout the vehicle and retained by many differ-
ent methods. These circuits may be connected to each
other, to the vehicle electrical system and to the
VTSS components through the use of a combination
of soldered splices, splice block connectors, and many
different types of wire harness terminal connectorsand insulators. Refer to the appropriate wiring infor-
mation. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
VEHICLE THEFT ALARM The VTA is available in
two different configurations for this vehicle: One con-
figuration is designed for vehicles manufactured for
sale in North America; while, the other configuration
is designed for vehicles manufactured for sale in
markets outside of North America, also referred to as
Rest-Of-World or ROW. In addition, the VTA for
ROW is available in two versions: base and premium.
All vehicles equipped with VTA are also equipped
with the Remote Keyless Entry (RKE) system and
the Sentry Key Immobilizer System (SKIS), regard-
less of their market destination. The North American
and ROW base version of the VTA provides perimeter
vehicle protection by monitoring the vehicle doors,
the tailgate, the rear flip-up glass and, for vehicles
built for certain markets where it is required equip-
ment, the hood. If unauthorized vehicle use or tam-
pering is detected, these systems respond by pulsing
the horn and flashing certain exterior lamps. The
ROW premium version of the VTA is only available
KJVEHICLE THEFT SECURITY 8Q - 1

in vehicles manufactured for sale in certain markets
where it is required equipment. The ROW premium
version of the VTA provides the same perimeter pro-
tection features as the base version, but adds interior
vehicle intrusion protection. The ROW premium VTA
also replaces the pulsing horn feature of the base
version with an alarm siren as the audible deterrent,
while retaining the flashing exterior lamps visual
deterrent.The VTA includes the following major components,
which are described in further detail elsewhere in
this service information:
²Body Control Module- The Body Control
Module (BCM) is located on the Junction Block (JB)
under the driver side outboard end of the instrument
panel. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/BODY CONTROL MODULE
- DESCRIPTION).
Fig. 1 Vehicle Theft Security System
1 - SIREN MODULE
2 - BODY CONTROL MODULE
3 - SENTRY KEY IMMOBILIZER MODULE4 - DOOR CYLINDER LOCK SWITCH (2)
5 - INTRUSION TRANSCEIVER MODULE
8Q - 2 VEHICLE THEFT SECURITYKJ
VEHICLE THEFT SECURITY (Continued)

²Combination Flasher- An electronic combina-
tion flasher is integral to the hazard switch located
in the center of the instrument panel above the
radio. (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR/COMBINATION FLASHER -
DESCRIPTION).
²Door Ajar Switch- A door ajar switch is inte-
gral to the latch of each door in the vehicle. (Refer to
8 - ELECTRICAL/LAMPS/LIGHTING - INTERIOR/
DOOR AJAR SWITCH - DESCRIPTION).
²Door Cylinder Lock Switch- For North
American vehicles only, a door cylinder lock switch is
located on the back of the lock cylinder of each front
door. (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY/DOOR CYLINDER LOCK SWITCH -
DESCRIPTION).
²Flip-Up Glass Ajar Switch- A flip-up glass
ajar switch is integral to the rear flip-up glass latch,
located on the top of the tailgate near the center.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
INTERIOR/FLIP-UP GLASS AJAR SWITCH -
DESCRIPTION).
²Hood Ajar Switch- A hood ajar switch is
located beneath the hood panel on the right inner
fender side shield of vehicles built for sale in certain
markets where it is required equipment. (Refer to 8 -
ELECTRICAL/VEHICLE THEFT SECURITY/HOOD
AJAR SWITCH - DESCRIPTION).
²Horn Relay- A horn relay is located on the
Junction Block (JB) under the driver side outboard
end of the instrument panel. (Refer to 8 - ELECTRI-
CAL/HORN/HORN RELAY - DESCRIPTION).
²Intrusion Transceiver Module- An Intrusion
Transceiver Module (ITM) is located near the center
of the headliner in the passenger compartment of
vehicles built for sale in certain markets where it is
required equipment. (Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/UK SECURITY SYSTEM
MODULE - DESCRIPTION).
²Security Indicator- A security indicator is
located in the ElectroMechanical Instrument Cluster
(EMIC) on the instrument panel in front of the driver
side front seat. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER/SECURITY INDICATOR -
DESCRIPTION).
²Siren- An alarm siren is located on the front
extension of the right front wheel house panel in the
engine compartment of vehicles built for sale in cer-
tain markets where it is required equipment. (Refer
to 8 - ELECTRICAL/VEHICLE THEFT SECURITY/
SIREN - DESCRIPTION).
²Tailgate Ajar Switch- A tailgate ajar switch is
integral to the latch for the tailgate in the vehicle.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
INTERIOR/TAILGATE AJAR SWITCH - DESCRIP-
TION).SENTRY KEY IMMOBILIZER SYSTEM The Sen-
try Key Immobilizer System (SKIS) is available as a
factory-installed option on this model. Vehicles
equipped with the Vehicle Theft Alarm (VTA) are also
equipped with SKIS. The SKIS provides passive vehi-
cle protection by preventing the engine from operat-
ing unless a valid electronically encoded key is
detected in the ignition lock cylinder. The SKIS
includes the following major components, which are
described in further detail elsewhere in this service
information:
²Powertrain Control Module- The Powertrain
Control Module (PCM) is located on the left inner
fender shield in the engine compartment near the
dash panel. (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/POWERTRAIN
CONTROL MODULE - DESCRIPTION).
²Sentry Key Immobilizer Module- The Sentry
Key Immobilizer Module (SKIM) is located beneath
the steering column shrouds on the right side of the
steering column near the ignition lock cylinder hous-
ing. (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/SENTRY KEY IMMOBILIZER
MODULE - DESCRIPTION).
²Sentry Key Transponder- The Sentry Key
transponder is molded into the head of the ignition
key, and concealed by a gray molded rubber cap.
(Refer to 8 - ELECTRICAL/VEHICLE THEFT SECU-
RITY/TRANSPONDER KEY - DESCRIPTION).
²SKIS Indicator- The SKIS indicator is located
in the ElectroMechanical Instrument Cluster (EMIC)
on the instrument panel in front of the driver side
front seat. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER/SPEED CONTROL INDICATOR -
DESCRIPTION).
OPERATION
The Vehicle Theft Security System (VTSS) is
divided into two basic subsystems: Vehicle Theft
Alarm (VTA) and Sentry Key Immobilizer System
(SKIS). Following are paragraphs that briefly
describe the operation of each of these two sub-
systems.
VEHICLE THEFT ALARM The Body Control Mod-
ule (BCM) is used on this model to control and inte-
grate many of the electronic functions and features
included in the Vehicle Theft Alarm (VTA). The BCM
receives hard wired inputs indicating the status of
the door ajar switches, the door cylinder lock
switches, the ignition switch, the tailgate ajar switch,
the tailgate cylinder lock switch, the flip-up glass
ajar switch, the power lock switches and, in vehicles
built for certain markets where it is required, 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-
KJVEHICLE THEFT SECURITY 8Q - 3
VEHICLE THEFT SECURITY (Continued)

these outputs vary by the requirements of the mar-
ket for which the vehicle is manufactured. In all
cases, the visual output will be a flashing on and off
of the exterior lamps. For vehicles equipped with the
North American or the ROW base version of the
VTA, the audible output will be a pulsing of the horn.
For vehicles with the ROW premium version of the
VTA, the audible output will be a cycling of the
alarm siren. See the owner's manual in the vehicle
glove box for details of the alarm output require-
ments of the specific market for which the vehicle
was manufactured. The inputs that will trigger the
alarm include the door ajar switches, the tailgate
ajar switch, the flip-up glass ajar switch, and in vehi-
cles built for certain markets where they are
required, the hood ajar switch and the Intrusion
Transceiver Module (ITM).
²TAMPER ALERT- The VTA tamper alert fea-
ture will pulse the horn (or the alarm siren for the
ROW premium version of the VTA) three times upon
VTA disarming, if the alarm was triggered and has
since timed-out. This feature alerts the vehicle oper-
ator that the VTA alarm was activated while the
vehicle was unattended.
²INTRUSION ALARM- The intrusion alarm is
an exclusive feature of the ROW premium version of
the VTA, which is only available in certain markets
where it is required. When the VTA is armed, a
motion sensor in the Intrusion Transceiver Module
(ITM) monitors the interior of the vehicle for move-
ment. If motion is detected, the ITM sends an elec-
tronic message to the BCM over the PCI data bus to
invoke the visual alarm feature, and sends an elec-
tronic message to the alarm siren in the engine com-
partment over a dedicated serial bus to invoke the
audible alarm feature. The motion detect feature of
the ITM can be disabled by depressing the ªLockº
button on the RKE transmitter three times within
fifteen seconds during VTA arming, while the secu-
rity indicator is still flashing rapidly. The VTA pro-
vides a single short siren ªchirpº as an audible
confirmation 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 logic in the ITM keeps its intrusion
alarm function dormant until it is enabled using a
DRBIIItscan tool. The intrusion alarm function of
the ITM is enabled on vehicles equipped with thisoption at the factory, but a service replacement ITM
must be configured and enabled by the dealer using a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
SENTRY KEY IMMOBILIZER SYSTEM The Sen-
try Key Immobilizer System (SKIS) is designed to
provide passive protection against unauthorized vehi-
cle use by disabling the engine after about two sec-
onds 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 customer inter-
vention. The SKIS uses Radio Frequency (RF) com-
munication to obtain confirmation that the key in the
ignition switch is a valid key for operating the vehi-
cle. The microprocessor-based SKIS hardware and
software also use electronic messages to communi-
cate with other electronic modules in the vehicle over
the Programmable Communications Interface (PCI)
data bus. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/COMMUNICATION - OPER-
ATION).
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 Diagnostic
Trouble Codes (DTC's) if a system malfunction is
detected. The SKIS can be diagnosed, and any stored
DTC's can be retrieved using a DRBIIItscan tool.
Refer to the appropriate diagnostic information.
KJVEHICLE THEFT SECURITY 8Q - 5
VEHICLE THEFT SECURITY (Continued)

continuity. If OK, go to Step 6. If not OK, repair the
open ground circuit(s) to ground (G202) as required.
(6) Reconnect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
instrument panel wire harness connector for the
SKIM. If OK, go to Step 7. If not OK, repair the open
fused B(+) circuit between the SKIM and the JB as
required.
(7) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run-start) circuit cavity of the instrument
panel wire harness connector for the SKIM. If OK,
use a DRBIIItscan tool to complete the diagnosis of
the SKIS. Refer to the appropriate diagnostic infor-
mation. If not OK, repair the open fused ignition
switch output (run-start) circuit between the SKIM
and the JB as required.
SKIS INDICATOR FLASHES UPON IGNITION ªONº OR
LIGHTS SOLID FOLLOWING BULB TEST
A SKIS indicator that flashes following the ignition
switch being turned to the On position indicates that
an invalid key has been detected, or that a key-re-
lated fault has been set. A SKIS indicator that lights
solid following a successful bulb test indicates that
the SKIM has detected a system malfunction or that
the SKIS is inoperative. In either case, fault informa-
tion will be stored in the SKIM memory. For retrieval
of this fault information and further diagnosis of the
SKIS, the PCI data bus, the SKIM electronic mes-
sage outputs to the instrument cluster that control
the SKIS indicator and chime, or the electronic mes-
sage inputs and outputs between the SKIM and the
Powertrain Control Module (PCM) that control
engine operation, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information. Fol-
lowing are preliminary troubleshooting guidelines to
be followed during diagnosis using a DRBIIItscan
tool:
(1) Using the DRBIIItscan tool, read and record
the faults as they exist in the SKIM when you first
begin your diagnosis of the vehicle. It is important to
document these faults because the SKIM does not
differentiate between historical faults (those that
have occurred in the past) and active faults (those
that are currently present). If this problem turns out
to be an intermittent condition, this information may
become invaluable to your diagnosis.
(2) Using the DRBIIItscan tool, erase all of the
faults from the SKIM.
(3) Cycle the ignition switch to the Off position,
then back to the On position.
(4) Using the DRBIIItscan tool, read any faults
that are now present in the SKIM. These are the
active faults.(5) Using this active fault information, refer to the
proper procedure in the appropriate diagnostic infor-
mation for the specific additional diagnostic steps.
STANDARD PROCEDURE
STANDARD PROCEDURE - SKIS
INITIALIZATION
The Sentry Key Immobilizer System (SKIS) must
be initialized following a Sentry Key Immobilizer
Module (SKIM) replacement. SKIS initialization
requires the use of a DRBIIItscan tool. Initialization
will also require that you have access to the unique
four-digit PIN code that was assigned to the original
SKIM. The PIN codemustbe used to enter the
Secured Access Mode in the SKIM. This PIN number
may be obtained from the vehicle owner, from the
original vehicle invoice, or from the DaimlerChrysler
Customer Center. (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES - STANDARD PRO-
CEDURE - PCM/SKIM PROGRAMMING).
NOTE: If a Powertrain Control Module (PCM) is
replaced on a vehicle equipped with the Sentry Key
Immobilizer System (SKIS), the unique Secret Key
data must be transferred from the Sentry Key
Immobilizer Module (SKIM) to the new PCM using
the PCM replacement procedure. This procedure
also requires the use of a DRBIIITscan tool and the
unique four-digit PIN code to enter the Secured
Access Mode in the SKIM. Refer to the appropriate
diagnostic information for the proper PCM replace-
ment procedures.
STANDARD PROCEDURE - SENTRY KEY
TRANSPONDER PROGRAMMING
All Sentry Keys included with the vehicle are pre-
programmed to work with the Sentry Key Immobi-
lizer System (SKIS) when it is shipped from the
factory. The Sentry Key Immobilizer Module (SKIM)
can be programmed to recognize up to a total of eight
Sentry Keys. When programming a blank Sentry Key
transponder, the key must first be cut to match the
ignition switch lock cylinder in the vehicle for which
it will be used. Once the additional or new key has
been cut, the SKIM must be programmed to recog-
nize it as a valid key. There are two possible methods
to program the SKIM to recognize a new or addi-
tional valid key, the Secured Access Method and the
Customer Learn Method. Following are the details of
these two programming methods.
8Q - 8 VEHICLE THEFT SECURITYKJ
VEHICLE THEFT SECURITY (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)

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

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)