2003 JEEP GRAND CHEROKEE security key

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 Driver Door Module
(DDM) when either front door key lock cylinder is in
the Lock, or Unlock positions. The DDM 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. 2).
(4) Remove the lock lever from the pin on the back
of the door lock cylinder.
Fig. 1 DOOR CYLINDER LOCK SWITCH
1 - SWITCH
2 - OUTSIDE DOOR HANDLE
3 - DOOR LOCK CYLINDER
Fig. 2 LOCK CYLINDER LEVER RETAINER RE
1 - LEVER
2 - RETAINER
3 - LOCK CYLINDER
4 - SWITCH
5 - PLIERS
6 - OUTSIDE DOOR HANDLE
8Q - 8 VEHICLE THEFT SECURITYWJ
DOOR CYLINDER LOCK SWITCH (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)

message inputs to and outputs from the alarm siren
module requires the use of a DRBIIItscan tool.
Refer to the appropriate diagnostic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the alarm siren module wiring har-
ness connector. (Fig. 9).
(3) Remove the screws that secure the alarm siren
module to the left frame rail.
(4) Remove the alarm siren module.
INSTALLATION
(1) Position the alarm siren module on to the left
frame rail. (Fig. 9).
(2) Install and tighten the screws that secure the
alarm siren moduleto the frame rail. Tighten the
screws to 6 N´m (50 in. lbs.).
(3) Reconnect the alarm siren module wiring har-
ness connector.
(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 requiredto configure the alarm siren module settings in the
ITM. Refer to the appropriate diagnostic informa-
tion.
SKIS INDICATOR LAMP
DESCRIPTION
A Sentry Key Immobilizer System (SKIS) indicator
lamp is standard equipment on all instrument clus-
ters, but is only functional on vehicles equipped with
the optional SKIS. The amber SKIS indicator lamp is
located to the right of the oil pressure gauge.
OPERATION
The Sentry Key Immobilizer System (SKIS) indica-
tor lamp gives an indication to the vehicle operator of
the status of the SKIS. This lamp is controlled by a
transistor on the instrument cluster circuit board
based upon messages received by the cluster from
the Sentry Key Immobilizer Module (SKIM) over the
Programmable Communications Interface (PCI) data
bus. The SKIS indicator lamp bulb receives battery
current on the instrument cluster circuit board
through the fused ignition switch output (st-run) cir-
cuit whenever the ignition switch is in the On or
Start positions. The lamp bulb only illuminates when
it is provided a path to ground by the instrument
cluster transistor. The instrument cluster will turn
on the SKIS indicator lamp for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position, the SKIM tells the cluster
to illuminate the lamp for about three seconds.
²SKIS Lamp-On Message- Each time the clus-
ter receives a SKIS lamp-on message from the SKIM,
the lamp will be illuminated. The lamp can be
flashed on and off, or illuminated solid, as dictated
by the message from the SKIM. For more informa-
tion on the SKIS and the SKIS lamp control param-
eters, (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY - OPERATION - SENTRY KEY IMMO-
BILIZER SYSTEM). The lamp remains illuminated
until the cluster receives a lamp-off message from
the SKIM or until the ignition switch is turned to the
Off position, whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the lamp will be turned on
for the duration of the test to confirm the functional-
ity of the lamp and the cluster.
The SKIM performs a self-test each time the igni-
tion switch is turned to the On position to decide
whether the system is in good operating condition.
The SKIM then sends a message to the instrument
cluster. If the SKIS indicator lamp fails to light dur-
ing the bulb test, replace the bulb. For further diag-
nosis of the SKIS indicator lamp or the instrument
Fig. 9 Siren Remove/Install
1 - SIREN
2 - FRAME
8Q - 14 VEHICLE THEFT SECURITYWJ
SIREN (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-39 VEHICLE THEFT SECURITY SYSTEM
Component Page
Automatic Headlamp Light
Sensor/VTSS LED.................. 8W-39-3
Body Control Module . . . 8W-39-2, 3, 4, 5, 7, 8, 9, 10
Clockspring....................... 8W-39-7, 8
Diagnostic Junction Port............... 8W-39-9
Driver Cylinder Lock Switch............ 8W-39-6
Driver Door Lock Motor/Ajar Switch...... 8W-39-6
Driver Door Module................ 8W-39-6, 11
Engine Starter Motor Relay............ 8W-39-2
Fuse 7........................ 8W-39-3, 9, 11
Fuse 8............................. 8W-39-2
Fuse 18.......................... 8W-39-7, 8
Fuse 22.......................... 8W-39-2, 9
Fuse 28............................ 8W-39-2
G106............................. 8W-39-10
G108............................ 8W-39-7, 8
G200.............................. 8W-39-9
G300............................ 8W-39-5, 6Component Page
G301....................... 8W-39-4, 5, 6, 11
Hood Ajar Switch................... 8W-39-10
Horn No. 1....................... 8W-39-7, 8
Horn No. 2....................... 8W-39-7, 8
Horn Relay....................... 8W-39-7, 8
Horn Switch...................... 8W-39-7, 8
Ignition Switch...................... 8W-39-2
Junction Block........ 8W-39-2, 3, 4, 5, 7, 8, 9, 11
Left Liftgate Ajar Switch.............. 8W-39-4
Left Rear Door Lock Motor/Ajar Switch . . . 8W-39-5
Liftgate Flip-Up Ajar Switch............ 8W-39-4
Passenger Door Lock Motor/Ajar Switch . . . 8W-39-6
Passenger Door Module............... 8W-39-6
Power Distribution Center......... 8W-39-2, 7, 8
Remote Keyless Module.............. 8W-39-11
Right Liftgate Ajar Switch............. 8W-39-4
Right Rear Door Lock Motor/Ajar Switch . . 8W-39-5
Sentry Key Immobilizer Module......... 8W-39-9
WJ8W-39 VEHICLE THEFT SECURITY SYSTEM 8W - 39 - 1