2002 JEEP GRAND CHEROKEE cylinder head

SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
31). The increase in electrode gap will be consider-
ably in excess of 0.001 inch per 2000 miles of opera-
tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.
CAUTION: If the engine is equipped with copper
core ground electrode, or platinum tipped spark
plugs, they must be replaced with the same type/
number spark plug as the original. If another spark
plug is substituted, pre-ignition will result.
REMOVAL
CAUTION: If equipped with a 4.7L H.O. (High-Out-
put) engine, never substitute the original platinum
tipped spark plug with a different part number. Seri-
ous engine damage may result.
On the 4.0L 6±cylinder engine, the spark plugs are
located below the coil rail assembly. On the 4.7L V±8
engine, each individual spark plug is located under
each ignition coil.
(1) 4.0L 6±Cylinder Engine: Prior to removing
spark plug, spray compressed air around spark plug
hole and area around spark plug. This will help pre-
vent foreign material from entering combustion
chamber.
(2) 4.7L V±8 Engine: Prior to removing spark plug,
spray compressed air around base of ignition coil at
cylinder head. This will help prevent foreign material
from entering combustion chamber.
(3) On the 4.0L engine the coil rail assembly must
be removed to gain access to any/all spark plug.
Refer to Ignition Coil Removal/Installation. On the4.7L V-8 engine each individual ignition coil must be
removed to gain access to each spark plug. Refer to
Ignition Coil Removal/Installation.
(4) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert. If
equipped with a 4.7L V-8 engine, also check condition
of coil o-ring and replace as necessary.
(5) Inspect spark plug condition. Refer to Spark
Plug Conditions.
CLEANING
Except 4.7L H.O. Engine:The plugs may be
cleaned using commercially available spark plug
cleaning equipment. After cleaning, file center elec-
trode flat with a small point file or jewelers file
before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean spark plugs. Metallic deposits will remain
on spark plug insulator and will cause plug misfire.
4.7L H.O. Engine:Never clean spark plugs on the
4.7L H.O. engine. Damage to the platinum rivet on
the center electrode will result.
INSTALLATION
CAUTION: The standard 4.7L V-8 engine is
equipped with copper core ground electrode spark
plugs. They must be replaced with the same type/
number spark plug as the original. If another spark
plug is substituted, pre-ignition will result.
CAUTION: If equipped with a 4.7L H.O. (High-Out-
put) engine, never substitute the original platinum
tipped spark plug with a different type/part number.
Serious engine damage may result.
Special care should be taken when installing spark
plugs into cylinder head spark plug wells. Be sure
plugs do not drop into plug wells as ground straps
may be bent resulting in a change in plug gap, or
electrodes can be damaged.
Always tighten spark plugs to specified torque. Over
tightening can cause distortion resulting in a change
in spark plug gap or a cracked porcelain insulator.
(1) Start spark plug into cylinder head by hand to
avoid cross threading.
(2) 4.0L 6±Cylinder Engine: Tighten spark plugs to
35-41 N´m (26-30 ft. lbs.) torque.
(3) 4.7L V±8 Engine: Tighten spark plugs to 27
N´m (20 ft. lbs.) torque.
(4)
4.7L V±8 Engine: Before installing coil(s), check
condition of coil o-ring and replace as necessary. To aid
in coil installation, apply silicone to coil o-ring.
(5) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.
Fig. 31 SPARK PLUG OVERHEATING
1 - BLISTERED WHITE OR GRAY COLORED INSULATOR
8I - 18 IGNITION CONTROLWJ
SPARK PLUG (Continued)

²RETRAIN TIRE SENSORS?- This program-
mable feature only applies to vehicles equipped with
the optional tire pressure monitoring system. The
options include Yes and No. The default is No. When
Yes is selected and the menu button is depressed, the
EVIC will enter the training mode starting with the
left front tire.
²EASY EXIT SEAT?- This programmable fea-
ture only applies to vehicles equipped with the
optional memory system. The options include Yes and
No. The default is No. When Yes is selected, the
driver seat moves rearward about 55 millimeters
(two inches) or to the farthest rearward position,
whichever comes first, when the key is removed from
the ignition switch lock cylinder. This provides addi-
tional ease for exiting from the vehicle. The seat will
automatically return to the memory system setting
position when the Driver 1 or Driver 2 button of the
memory switch on the door panel is depressed or, if
theREMOTE LINKED TO MEMORYprogramma-
ble feature is enabled, when the RKE Unlock button
is depressed. While not automatic, an easy entry fea-
ture can be obtained by enabling theEASY EXIT
SEATfeature and disabling theREMOTE LINKED
TO MEMORYfeature. Then theEASY EXIT SEAT
feature will move the seat back, but the RKE unlock
event will not reposition the seat. Thus, the seat
remains positioned for easy entry, and the memory
switch on the door panel can be depressed after
entering the vehicle to return the seat to the desired
memory position.
STANDARD PROCEDURE - COMPASS
DEMAGNETIZING
A degaussing tool (Special Tool 6029) is used to
demagnetize, or degauss, the overhead console for-
ward mounting screw and the roof panel above the
overhead console. Equivalent units must be rated as
continuous duty for 110/115 volts and 60 Hz. They
must also have a field strength of over 350 gauss at 7
millimeters (0.25 inch) beyond the tip of the probe.
To demagnetize the roof panel and the overhead
console forward mounting screw, proceed as follows:
(1) Be certain that the ignition switch is in the Off
position, before you begin the demagnetizing proce-
dure.
(2) Connect the degaussing tool to an electrical
outlet, while keeping the tool at least 61 centimeters
(2 feet) away from the compass unit.
(3) Slowly approach the head of the overhead con-
sole forward mounting screw with the degaussing
tool connected.
(4) Contact the head of the screw with the plastic
coated tip of the degaussing tool for about two sec-
onds.(5) With the degaussing tool still energized, slowly
back it away from the screw. When the tip of the tool
is at least 61 centimeters (2 feet) from the screw
head, disconnect the tool.
(6) Place a piece of paper approximately 22 by 28
centimeters (8.5 by 11 inches), oriented on the vehicle
lengthwise from front to rear, on the center line of
the roof at the windshield header (Fig. 3). The pur-
pose of the paper is to protect the roof panel from
scratches, and to define the area to be demagnetized.
(7) Connect the degaussing tool to an electrical
outlet, while keeping the tool at least 61 centimeters
(2 feet) away from the compass unit.
(8) Slowly approach the center line of the roof
panel at the windshield header, with the degaussing
tool connected.
(9) Contact the roof panel with the plastic coated
tip of the degaussing tool. Be sure that the template
is in place to avoid scratching the roof panel. Using a
slow, back-and-forth sweeping motion, and allowing
13 millimeters (0.50 inch) between passes, move the
tool at least 11 centimeters (4 inches) to each side of
the roof center line, and 28 centimeters (11 inches)
back from the windshield header.
(10) With the degaussing tool still energized,
slowly back it away from the roof panel. When the
Fig. 3 Roof Demagnetizing Pattern
8M - 4 MESSAGE SYSTEMSWJ
OVERHEAD CONSOLE (Continued)

²Ten-way power drivers and passenger seats
with Memory- This power seat option is standard
on Overland models and optional on Limited models.
This option includes a six-way adjustable seat cush-
ion track with power seat back recliners and power
lumbar supports. Heated Seats are standard with
this option.
Refer toHeated Seat Systemfor more informa-
tion on the heated seat option. Refer toMemory
Systemin the Memory System section of this group
for more information on the memory system.
The power seat system includes the following com-
ponents:
²Power lumbar adjuster (ten-way power seat
only)
²Power lumbar switch (ten-way power seat only)
²Power seat recliner (ten-way power seat only)
²Power seat switch
²Power seat track.
Refer toPower Seatin Wiring Diagrams for com-
plete circuit diagrams. Following are general descrip-
tions of the major components in the power seat/
memory seat system.
DESCRIPTION - MEMORY SYSTEM
An electronic memory system is standard equip-
ment on the Limited model. The memory system is
able to store and recall the driver side power seat
positions (including the power recliner position), and
both outside power mirror positions for two drivers.
For vehicles with a radio connected to the Program-
mable Communications Interface (PCI) data bus net-
work, the memory system is also able to store and
recall up to twenty - ten AM and ten FM - radio sta-
tion presets for two drivers. The memory system also
will store and recall the last station listened to for
each driver, even if it is not one of the twenty preset
stations.
The memory system will automatically return to
all of these settings when the corresponding num-
bered and color-coded button (Driver 1 - Black, or
Driver 2 - Gray) of the memory switch on the driver
side front door trim panel is depressed, or when the
doors are unlocked using the corresponding num-
bered and color-coded (Driver 1 - Black, or Driver 2 -
Gray) Remote Keyless Entry (RKE) transmitter. A
customer programmable feature of the memory sys-
tem allows the RKE recall of memory features to be
disabled in cases where there are more than two
drivers of the vehicle.
The memory system also has a customer program-
mable easy exit feature that will move the driver
seat rearward 55 millimeters (two inches) or to the
end of its travel, whichever occurs first, when the key
is removed from the ignition switch lock cylinder.A Memory Seat Module (MSM) or Memory Heated
Seat Module (MHSM) are used on this model to con-
trol and integrate the many electronic functions and
features included in the memory system. On vehicles
equipped with the heated seat system option, the
MHSM also controls the functions and features of
that system.
The memory system includes the following compo-
nents:
²Memory seat module (or memory heated seat
module)
²Memory switch
²Position potentiometers on both outside power
mirrors
²Position potentiometers on the driver side power
seat track and power seat recliner motors.
²Radio receiver (if PCI data bus capable).
Certain functions and features of the memory sys-
tem rely upon resources shared with other electronic
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. The
PCI data bus network allows the sharing of sensor
information. This helps to reduce wire harness com-
plexity, internal controller hardware, and component
sensor current loads. At the same time, this system
provides increased reliability, enhanced diagnostics,
and allows the addition of many new feature capabil-
ities. For diagnosis of these electronic modules or of
the PCI data bus network, the use of a DRBtscan
tool and the proper Diagnostic Procedures manual
are recommended.
The other electronic modules that may affect mem-
ory system operation are as follows:
²Body Control Module (BCM)- Refer toBody
Control Modulein Electronic Control Modules for
more information.
²Driver Door Module (DDM)- Refer toDoor
Modulein Electronic Control Modules for more
information.
²Electronic Vehicle Information Center
(EVIC)- Refer toElectronic Vehicle Information
Centerin Overhead Console Systems for more infor-
mation.
²Passenger Door Module (PDM)- Refer to
Door Modulein Electronic Control Modules for
more information.
²Powertrain Control Module (PCM)- Refer to
Powertrain Control Modulein Electronic Control
Modules for more information.
²Radio Receiver- Refer toRadio Receiverin
Audio Systems for more information.
Refer toHeated Seat Systemfor more informa-
tion on this system. Refer toRemote Keyless Entry
Systemin Power Lock Systems for more information
on the RKE system. Refer toPower Mirrorin
Power Mirror Systems for more information on the
WJPOWER SEAT SYSTEM 8N - 19
POWER SEAT SYSTEM (Continued)

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)

switch, or when the ªLockº button on the Remote
Keyless Entry (RKE) transmitter is depressed. The
powerlock switch will not initiate the pre-arming
sequence if the key is in the ignition switch. When
the VTA is pre-armed, the arming sequence is
delayed until all of the doors, the tailgate and the
flip-up glass are closed.
ARMING
Passive arming of the VTSS occurs when the vehi-
cle is exited with the key removed from the ignition
switch, the headlamps are turned off, and the doors
are locked while they are open using the power lock
switch. The power lock switch will not function if the
key is in the ignition switch or the headlamps are
turned on with the driver side front door open. The
VTSS will not arm if the driver side front door is
locked using the key in the lock cylinder or using the
mechanical lock button. Active arming of the VTSS
occurs when the ªLockº button on the Remote Key-
less Entry (RKE) transmitter is depressed to lock the
vehicle, even if the doors and/or the liftgate are open
when the RKE transmitter Lock button is depressed.
However, the VTSS arming will not be complete until
all of the doors, the liftgate and the liftgate flip-up
glass are closed. On vehicles equipped with the hood
ajar switch, VTSS arming will complete if the hood is
open, but the underhood area will not be protected
unless the hood is closed when the VTSS is armed.
Following successful passive or active VTSS arm-
ing, the VTSS indicator on the top of the instrument
panel will flash rapidly for about sixteen seconds
after the illuminated entry system times out. This
indicates that VTSS arming is in progress. Once the
sixteen second arming function is successfully com-
pleted, the indicator will flash at a slower rate, indi-
cating that the VTSS is armed.
DISARMING
Passive disarming of the VTSS occurs when the
vehicle is unlocked using the key to unlock the driver
side front door. Active disarming of the VTSS occurs
when the vehicle is unlocked by depressing the
ªUnlockº button of the Remote Keyless Entry (RKE)
transmitter. Once the alarm has been activated,
either disarming method will also deactivate the
alarm. Depressing the ªPanicº button on the RKE
transmitter will also disarm the VTSS, but the horn
will continue to pulse and the exterior lamps will
continue to flash for about three minutes as part of
the Panic feature function. The Panic feature is over-
ridden if the ªPanicº button is depressed a second
time, or if a vehicle speed of about 24 kilometers-per-
hour (15 miles-per-hour) is attained.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 technician or vehicle operator
will have to actively or passively disarm the alarm
system after the battery is reconnected. The pow-
er-up mode will also apply if the battery goes dead
while the system is armed, and battery jump-starting
is then attempted. The VTSS will be armed until it is
actively or passively disarmed. If the VTSS is in the
disarmed mode prior to a battery disconnect or fail-
ure, it will remain disarmed after the battery is
reconnected or replaced, or if jump-starting is
attempted.
ALARM
The VTA alarm output varies by the version of the
VTA with which the vehicle is equipped. In all cases,
the alarm provides both visual and audible outputs;
however, the time intervals of these outputs vary by
the requirements of the market for which the vehicle
is manufactured. In all cases, the visual output will
be a flashing of the exterior lamps. For vehicles
equipped with North American or the base version of
the VTA, the audible output will be the pulsing of the
horn. For vehicles with the premium version of the
VTA, the audible output will be the cycling of the
siren. The inputs that will trigger the alarm include
the door ajar switch, the flip-up glass ajar switch,
and in vehicles built for certain markets where they
are required, the hood ajar switch and the Intrusion
Transceiver Module (ITM).
TAMPER ALERT
The VTSS tamper alert feature will sound the horn
(or the alarm siren for the premium version) three
times upon VTA disarming, if the alarm was trig-
gered and has since timed-out (about eighteen min-
utes). This feature alerts the vehicle operator that
the VTA alarm was activated while the vehicle was
unattended.
INTRUSION ALARM
The Intrusion Alarm is an exclusive feature of the
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 movement. If motion is detected, the
ITM sends a message to the BCM over the PCI bus
to invoke the visual alarm feature, and sends a mes-
sage to the alarm siren over a dedicated serial bus to
invoke the audible alarm feature. The motion detec-
WJVEHICLE THEFT SECURITY 8Q - 3
VEHICLE THEFT SECURITY (Continued)

The ITM microprocessor continuously monitors
inputs from its on-board motion sensor as well as
inputs from the BCM and the alarm siren module.
The ITM motion sensor 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 mov-
ing 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 indi-
cator is still flashing rapidly or by cycling the key in
the driver door cylinder from the center to the lock
position. 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 mes-
sage to the BCM over the PCI data bus to flash the
exterior lighting and send a 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
message to the ITM and the ITM sends an message
to the BCM over the PCI data bus to flash the exte-
rior lighting and send a 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 reoccur for fifty ignition cycles, the ITM will
automatically erase the stored DTC.
The ITM is connected to the vehicle electrical sys-
tem through the overhead wire harness. The ITM
receives battery voltage on a B(+) circuit through a
fuse in the Junction Block (JB), and is grounded to
the chassis at G303. 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 con-
ventional diagnostic tools and procedures. However,
conventional diagnostic methods will not prove con-
clusive in the diagnosis of the ITM, the PCI data bus
network, or the electronic message inputs to and out-
puts from the ITM. The most reliable, efficient, and
accurate means to diagnose the ITM, the PCI data
bus network, and the message inputs to and outputsfrom the ITM requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) While pulling downward lightly on the rear cor-
ner 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 release the two integral rear latch features
of the module from the mounting bracket above the
headliner (Fig. 7).
(3) Pull the ITM trim cover rearward far enough
to disengage the two front latch features of the mod-
ule 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.
(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.
(3) Align the two front latch features of the ITM
with the two front latch receptacles of the mounting
bracket above the headliner (Fig. 8).
(4) Push the ITM trim cover forward far enough to
insert the two rear latch features of the module into
Fig. 7 INTRUSION TRANSCEIVER MODULE
REMOVE
1 - SMALL SCREWDRIVER
2 - HEADLINER
3 - SERVICE HOLES
4 - ITM
8Q - 12 VEHICLE THEFT SECURITYWJ
INTRUSION TRANSCEIVER MODULE (Continued)

cluster circuitry that controls the lamp, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). If the instrument cluster turns
on the SKIS indicator lamp after the bulb test, either
solid or flashing, it indicates that a SKIS malfunction
has occurred or that the SKIS is inoperative. For
proper diagnosis of the SKIS, the PCI data bus, or
the message inputs to the instrument cluster that
control the SKIS indicator lamp, a DRBIIItscan tool
and the appropriate diagnostic information are
required.
TRANSPONDER KEY
DESCRIPTION
Each ignition key used in the Sentry Key Immobi-
lizer System (SKIS) has an integral transponder chip
(Fig. 10). 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 transponder
chip is concealed beneath the molded rubber cap,
where it is molded into the head of the metal key.
Each new Sentry Key has a unique transponder iden-
tification code permanently programmed into it by
the manufacturer. The Sentry Key transponder if
faulty or damaged, 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 waits for a RF response from the
transponder through the same antenna. The Sentry
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.
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).
VTSS INDICATOR
DESCRIPTION
The Vehicle Theft Security System (VTSS) indica-
tor consists of a red Light-Emitting Diode that is
mounted and integral to the automatic headlamp
light sensor photo diode unit, which is located on the
top of the instrument panel. The remainder of the
housing including the mount and the electrical con-
nection are concealed beneath the instrument panel
top cover.
The VTSS indicator cannot be adjusted or repaired
the entire automatic headlamp light sensor/VTSS
indicator must be replaced. (Refer to 8 - ELECTRI-
CAL/LAMPS/LIGHTING - EXTERIOR/AUTO HEAD-
LAMP SENSOR - REMOVAL).
Fig. 10 Sentry Key Immobilizer Transponder
1 - MOLDED CAP
2 - TRANSPONDER CHIP
3 - MOLDED CAP REMOVED
4 - TRANSPONDER KEY
WJVEHICLE THEFT SECURITY 8Q - 15
SKIS INDICATOR LAMP (Continued)

8W-02 COMPONENT INDEX
Component Page
A/C Compressor Clutch................. 8W-42
A/C Pressure Transducer................ 8W-42
Accelerator Pedal Position Sensor......... 8W-30
Accessory Delay Relay.................. 8W-64
Adjustable Pedals..................... 8W-30
Airbags............................. 8W-43
Ambient Temperature Sensor............ 8W-45
Antennas............................ 8W-47
Ash Receiver Lamp.................... 8W-44
Auto Shut Down Relay................. 8W-30
Automatic Day/Night Mirror............. 8W-49
Automatic Headlamp Light Sensor/VTSS
LED.............................. 8W-39
Automatic Zone Control Module.......... 8W-42
Back-Up Lamp Relay................... 8W-51
Battery Temperature Sensor............. 8W-30
Battery............................. 8W-20
Blend Door Motor/Actuator.............. 8W-42
Blower Motor......................... 8W-42
Body Control Module................... 8W-45
Boost Pressure Sensor.................. 8W-30
Brake Lamp Switch.................... 8W-33
Camshaft Position Sensor............... 8W-30
Capacitors........................... 8W-30
Cargo Lamp.......................... 8W-44
Center High Mounted Stop Lamp......... 8W-51
Cigar Lighter......................... 8W-41
Circuit Breakers...................... 8W-12
Clockspring.................. 8W-33, 41, 43, 47
Coil On Plugs......................... 8W-30
Coil Rail............................. 8W-30
Combination Flasher................... 8W-52
Compact Disc Changer.................. 8W-47
Controller Antilock Brake............... 8W-35
Coolant Level Sensor................... 8W-45
Courtesy Lamps....................... 8W-44
Crankcase Heater..................... 8W-30
Crankshaft Position Sensor.............. 8W-30
Cylinder Lock Switches................. 8W-61
Data Link Connector................... 8W-18
Diagnostic Junction Port................ 8W-18
EGR Solenoid......................... 8W-30
Electric Brake........................ 8W-54
Electronic Speed Control Servo........... 8W-33
Engine Control Module................. 8W-30
Engine Coolant Temperature Sensor...... 8W-30
Engine Oil Pressure Sensor.............. 8W-30
Engine Starter Motor................... 8W-21
EVAP/Purge Solenoid................... 8W-30
Fog Lamps........................ 8W-50, 51
Fuel Injectors......................... 8W-30
Fuel Pressure Sensor................... 8W-30Component Page
Fuel Pressure Solenoid................. 8W-30
Fuel Pump........................... 8W-30
Fuel Tank Module..................... 8W-30
Fuses............................ 8W-10, 12
Fusible Link....................... 8W-10, 20
Grounds............................. 8W-15
Generator......................... 8W-20, 30
Glove Box Lamp...................... 8W-44
Glow Plugs........................... 8W-30
Headlamp Leveling Motor............... 8W-50
Heated Seats......................... 8W-63
High Beam Headlamps................. 8W-50
Hood Ajar Switch...................... 8W-39
Horns............................... 8W-41
Hydraulic Cooling Module............ 8W-30, 42
Idle Air Control Motor.................. 8W-30
Ignition Switch....................... 8W-10
Impact Sensors....................... 8W-43
Input Speed Sensor.................... 8W-31
Instrument Cluster.................... 8W-40
Intake Air Temperature Sensor........... 8W-30
Intake Port Swirl Actuator.............. 8W-30
Intrusion Transceiver Module............ 8W-49
Junction Block........................ 8W-12
Knock Sensor......................... 8W-30
Lamp Assemblies................... 8W-51, 52
Leak Detection Pump.................. 8W-30
License Lamps........................ 8W-51
Liftgate............................. 8W-61
Line Pressure Sensor................... 8W-31
Low Beam Headlamps.................. 8W-50
Low Beam Relay...................... 8W-50
Low Beam/Daytime Running Lamp Relay . . . 8W-50
Lumbar Motor........................ 8W-63
Lumbar Switch....................... 8W-63
Manifold Absolute Pressure Sensor........ 8W-30
Manual Temperature Control............. 8W-42
Mass Air Flow Sensor.................. 8W-30
Memory Set Switch................. 8W-62, 63
Mode Door Motor/Actuator............... 8W-42
Multi-Function Switch............... 8W-50, 53
Output Speed Sensor................... 8W-31
Overhead Map/Courtesy Lamp........... 8W-44
Oxygen Sensors....................... 8W-30
Park Brake Switch..................... 8W-40
Park Lamp........................... 8W-50
Park/Neutral Position Switch............ 8W-31
Park/Turn Signal Lamps................ 8W-50
Power Amplifier....................... 8W-47
Power Connector...................... 8W-41
Power Distribution Center............... 8W-10
Power Mirrors........................ 8W-62
WJ8W-02 COMPONENT INDEX 8W - 02 - 1