2003 JEEP GRAND CHEROKEE Program key

(2) If equipped, remove Transmission Control Mod-
ule (TCM).
(3) Remove coolant reserve/overflow tank.
(4) Remove cover over electrical connectors. Cover
snaps onto PCM.
(5) Carefully unplug three 32±way connectors at
PCM.
(6) Remove three PCM bracket-to-body mounting
nuts (Fig. 13).
(7) Remove PCM/PCM bracket assembly from
vehicle.
(8) Remove 3 PCM-to-PCM bracket bolts (screws)
(Fig. 14).
INSTALLATION
USE THE DRBIIItSCAN TOOL TO REPRO-
GRAM THE NEW POWERTRAIN CONTROL
MODULE (PCM) WITH THE VEHICLES ORIGI-
NAL IDENTIFICATION NUMBER (VIN) AND
THE VEHICLES ORIGINAL MILEAGE. IF THIS
STEP IS NOT DONE, A DIAGNOSTIC TROUBLE
CODE (DTC) MAY BE SET.
The PCM is located on the cowl panel in right/rear
side of engine compartment (Fig. 12).
(1) Check pins in three 32±way electrical connec-
tors for damage. Repair as necessary.
(2) Install PCM to its mounting bracket. Tighten
three mounting bolts to 3 N´m (25 in. lbs.) torque.
(3) Install PCM/PCM bracket to body. Install 3
nuts and tighten 9 N´m (80 in. lbs.) torque.
(4) Install three 32±way connectors.(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install coolant reserve/overflow tank.
(7) If equipped, install Transmission Control Mod-
ule (TCM).
(8) Connect negative cable to battery.
(9) Use the DRBIIItscan tool to reprogram new
PCM with vehicles original Identification Number
(VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) is the
primary component of the Sentry Key Immobilizer
System (SKIS) (Fig. 15). The SKIM is located in the
steering column, below the ignition lock cylinder
housing. The SKIM has an integral halo-like antenna
ring that extends from one side.
The SKIM cannot be adjusted or repaired. If faulty
or damaged, the entire SKIM unit must be replaced.
OPERATION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM transmits RF signals to,
and receives RF signals from the Sentry Key tran-
Fig. 14 Powertrain Control Module (PCM) Mounting
Bracket
1 - PCM BRACKET
2 - PCM
3 - PCM-TO-BRACKET SCREWS (3)
Fig. 15 Sentry Key Immobilizer Module
1 - STEERING COLUMN
2 - SKIM
3 - MOUNTING SCREW
WJELECTRONIC CONTROL MODULES 8E - 17
POWERTRAIN CONTROL MODULE (Continued)

sponder through a tuned antenna ring integral to the
SKIM housing. If this antenna ring is not mounted
properly around the ignition lock cylinder housing,
communication problems between the SKIM and the
transponder may arise. These communication prob-
lems will result in Sentry Key transponder-related
faults. The SKIM also communicates over the Pro-
grammable Communications Interface (PCI) data bus
with the Powertrain Control Module (PCM), the Elec-
troMechanical Instrument Cluster (EMIC), the Body
Control Module (BCM), and/or the DRBIIItscan tool.
The SKIM retains in memory the ID numbers of
any Sentry Key transponder that is programmed into
it. A maximum of eight transponders can be pro-
grammed into the SKIM. For added system security,
each SKIM is programmed with a unique Secret Key
code. This code is stored in memory, sent over the
PCI data bus to the PCM, and is encoded to the tran-
sponder of every Sentry Key that is programmed into
the SKIM. Another security code, called a PIN, is
used to gain access to the SKIM Secured Access
Mode. The Secured Access Mode is required during
service to perform the SKIS initialization and Sentry
Key transponder programming procedures. The
SKIM also stores the Vehicle Identification Number
(VIN) in its memory, which it learns through a PCI
data bus message from the PCM during SKIS initial-
ization.
In the event that a SKIM replacement is required,
the Secret Key code can be transferred to the new
SKIM from the PCM using the DRBIIItscan tool
and the SKIS replacement procedure. Proper comple-
tion of the SKIS initialization will allow the existing
Sentry Keys to be programmed into the new SKIM so
that new keys will not be required. In the event that
the original Secret Key code cannot be recovered,
SKIM replacement will also require new Sentry
Keys. The DRBIIItscan tool will alert the technician
during the SKIS replacement procedure if new Sen-
try Keys are required.
When the ignition switch is turned to the On posi-
tion, the SKIM transmits an RF signal to the tran-
sponder in the ignition key. The SKIM then waits for
an RF signal response from the transponder. If the
response received identifies the key as valid, the
SKIM sends a valid key message to the PCM over
the PCI data bus. If the response received identifies
the key as invalid, or if no response is received from
the key transponder, the SKIM sends an invalid key
message to the PCM. The PCM will enable or disable
engine operation based upon the status of the SKIM
messages. It is important to note that the default
condition in the PCM is an invalid key; therefore, if
no message is received from the SKIM by the PCM,
the engine will be disabled and the vehicle immobi-
lized after two seconds of running.The SKIM also sends indicator light status mes-
sages to the EMIC over the PCI data bus to tell the
EMIC how to operate the SKIS indicator. This indi-
cator light status message tells the EMIC to turn the
indicator on for about three seconds each time the
ignition switch is turned to the On position as a bulb
test. After completion of the bulb test, the SKIM
sends indicator light status messages to the EMIC to
turn the indicator off, turn the indicator on, or to
flash the indicator on and off. If the SKIS indicator
lamp flashes or stays on solid after the bulb test, it
signifies a SKIS fault. If the SKIM detects a system
malfunction and/or the SKIS has become inoperative,
the SKIS indicator will stay on solid. If the SKIM
detects an invalid key or if a key transponder-related
fault exists, the SKIS indicator will flash. If the vehi-
cle is equipped with the Customer Learn transponder
programming feature, the SKIM will also send mes-
sages to the EMIC to flash the SKIS indicator lamp,
and to the BCM to generate a single audible chime
tone whenever the Customer Learn programming
mode is being utilized. (Refer to 8 - ELECTRICAL/
VEHICLE THEFT SECURITY - STANDARD PRO-
CEDURE - SENTRY KEY 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) in SKIM memory if a system
malfunction is detected. The SKIM can be diagnosed,
and any stored DTC's can be retrieved using a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the steering column opening cover
from the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - REMOVAL).
8E - 18 ELECTRONIC CONTROL MODULESWJ
SENTRY KEY IMMOBILIZER MODULE (Continued)

(2) If testing the battery IN-THE-VEHICLE, make
certain all of the vehicle accessory loads are OFF,
including the ignition.The preferred test position
is at the battery terminal. If the battery is not
accessible, you may test using both the positive and
negative jumper posts. Select TESTING AT JUMPER
POST when connecting to that location.
(3) Connect the tester (Fig. 6) to the battery or
jumper posts, the red clamp to positive (+) and the
black clamp to negative (±).
NOTE: Multiple batteries connected in parallel must
have the ground cable disconnected to perform a
battery test. Failure to disconnect may result in
false battery test readings.
(4) Using the ARROW key selectinoroutof vehi-
cle testing and press ENTER to make a selection.
(5) If not selected, choose the Cold Cranking Amp
(CCA) battery rating. Or select the appropriate bat-
tery rating for your area (see menu). The tester will
then run its self programmed test of the battery and
display the results. Refer to the test result table
noted below.
CAUTION: If REPLACE BATTERY is the result of the
test, this may mean a poor connection between the
vehicle's cables and battery exists. After discon-
necting the vehicle's battery cables from the bat-
tery, retest the battery using the OUT-OF-VEHICLE
test before replacing.(6) While viewing the battery test result, press the
CODE button and the tester will prompt you for the
last 4 digits of the VIN. Use the UP/DOWN arrow
buttons to scroll to the correct character; then press
ENTER to select and move to the next digit. Then
press the ENTER button to view the SERVICE
CODE. Pressing the CODE button a second time will
return you to the test results.
BATTERY TEST RESULTS
GOOD BATTERY Return to service
GOOD - RECHARGE Fully charge battery and
return to service
CHARGE & RETEST Fully charge battery and
retest battery
REPLACE BATTERY Replace the battery and
retest complete system
BAD-CELL REPLACE Replace the battery and
retest complete system
NOTE: The SERVICE CODE is required on every
warranty claim submitted for battery replacement.
STANDARD PROCEDURE - BUILT-IN
INDICATOR TEST
An indicator (hydrometer) built into the top of the
battery case provides visual information for battery
testing (Fig. 7). Like a hydrometer, the built-in indi-
cator measures the specific gravity of the battery
electrolyte. The specific gravity of the electrolyte
reveals the battery state-of-charge; however, it will
not reveal the cranking capacity of the battery. A load
test must be performed to determine the battery
cranking capacity. Refer to Standard Procedures for
the proper battery load test procedures.
Fig. 6 MICRO 420 BATTERY AND CHARGING
SYSTEM TESTER
Fig. 7 Built-In Indicator
1 - SIGHT GLASS
2 - BATTERY TOP
3 - GREEN BALL
4 - PLASTIC ROD
WJBATTERY SYSTEM 8F - 11
BATTERY (Continued)

HORN
TABLE OF CONTENTS
page page
HORN SYSTEM
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - HORN SYSTEM . . . 2
HORN
DESCRIPTION..........................3
OPERATION............................3
DIAGNOSIS AND TESTING - HORN..........3
REMOVAL.............................3
INSTALLATION..........................4
HORN RELAY
DESCRIPTION..........................4OPERATION............................4
DIAGNOSIS AND TESTING - HORN RELAY....4
REMOVAL.............................5
INSTALLATION..........................5
HORN SWITCH
DESCRIPTION..........................6
OPERATION............................6
DIAGNOSIS AND TESTING - HORN SWITCH . . . 6
REMOVAL.............................7
INSTALLATION..........................7
HORN SYSTEM
DESCRIPTION
A dual-note electric horn system is standard facto-
ry-installed equipment on this model. The standard
equipment horn system features one low-note horn
unit and one high-note horn unit. The horn system
allows the vehicle operator to provide an audible
warning of the presence or approach of the vehicle to
pedestrians and the drivers of other vehicles in near
proximity. The horn system uses a non-switched
source of battery current so that the system will
remain functional, regardless of the ignition switch
position.
The horn system can also be activated by the Body
Control Module (BCM). The BCM is programmed to
activate the horns in order to provide the following
features:
²Remote Keyless Entry (RKE) system lock
request audible verification (except export)
²RKE system panic mode audible alert
²Vehicle Theft Security System (VTSS) audible
alarm.
This vehicle also offers several customer program-
mable features, which allows the selection of several
optional electronic features to suit individual prefer-
ences. Refer to Overhead Console for more informa-
tion on the customer programmable feature options.
Customer programmable feature options affecting the
horn system include:
²Sound Horn on Lock- Allows the option of
having the horn sound a short chirp as an audible
verification that the RKE system received a valid
Lock request from the RKE transmitter, or having no
audible verification.The horn system includes the following compo-
nents:
²Clockspring
²Horns
²Horn relay
²Horn switch
Certain functions and features of the horn system
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 DRB scan
tool and the proper Diagnostic Procedures manual
are recommended.
The other electronic modules that may affect horn
system operation are as follows:
²Body Control Module (BCM)(Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/BODY CONTROL/CENTRAL TIMER MODUL
- DESCRIPTION) for more information.
²Electronic Vehicle Information Center
(EVIC)(Refer to 8 - ELECTRICAL/OVERHEAD
CONSOLE/ELECTRONIC VEHICLE INFO CENTER
- DESCRIPTION) for more information.
(Refer to 8 - ELECTRICAL/RESTRAINTS/CLOCK-
SPRING - DESCRIPTION) for more information on
this component. Refer to the appropriate wiring
information. The wiring information includes wiring
diagrams, proper wire and connector repair proce-
dures, details of wire harness routing and retention,
WJHORN 8H - 1

The voltage signal produced by the knock sensor
increases with the amplitude of vibration. The PCM
receives the knock sensor voltage signal as an input.
If the signal rises above a predetermined level, the
PCM will store that value in memory and retard
ignition timing to reduce engine knock. If the knock
sensor voltage exceeds a preset value, the PCM
retards ignition timing for all cylinders. It is not a
selective cylinder retard.
The PCM ignores knock sensor input during engine
idle conditions. Once the engine speed exceeds a
specified value, knock retard is allowed.
Knock retard uses its own short term and long
term memory program.
Long term memory stores previous detonation
information in its battery-backed RAM. The maxi-
mum authority that long term memory has over tim-
ing retard can be calibrated.
Short term memory is allowed to retard timing up
to a preset amount under all operating conditions (as
long as rpm is above the minimum rpm) except at
Wide Open Throttle (WOT). The PCM, using short
term memory, can respond quickly to retard timing
when engine knock is detected. Short term memory
is lost any time the ignition key is turned off.
NOTE: Over or under tightening the sensor mount-
ing bolts will affect knock sensor performance, pos-
sibly causing improper spark control. Always use
the specified torque when installing the knock sen-
sors.
REMOVAL
4.7L High-Output Engine Only
The 2 knock sensors are bolted into the cylinder
block under the intake manifold (Fig. 22).
NOTE: The left sensor is identified by an identifica-
tion tag (LEFT). It is also identified by a larger bolt
head. The Powertrain Control Module (PCM) must
have and know the correct sensor left/right posi-
tions. Do not mix the sensor locations.
(1) Disconnect knock sensor dual pigtail harness
connector from engine wiring harness connector. This
connection is made near the right/rear of intake man-
ifold (Fig. 23).
(2) Remove intake manifold. Refer to Engine sec-
tion.
(3) Remove sensor mounting bolts (Fig. 22). Note
foam strip on bolt threads. This foam is used only to
retain the bolts to sensors for plant assembly. It is
not used as a sealant. Do not apply any adhesive,
sealant or thread locking compound to these bolts.
(4) Remove sensors from engine.
Fig. 22 KNOCK SENSOR LOCATION - 4.7L H.O.
1 - KNOCK SENSORS (2)
2 - MOUNTING BOLTS
3 - INTAKE MANIFOLD (CUTAWAY)
4 - PIGTAIL CONNECTOR
Fig. 23 KNOCK SENSOR ELEC. CONNECTOR - 4.7L
H.O.
1 - KNOCK SENSOR PIGTAIL HARNESS CONNECTOR
2 - ENGINE WIRING HARNESS
8I - 14 IGNITION CONTROLWJ
KNOCK SENSOR (Continued)

The VFD is diagnosed using the EMIC self-diag-
nostic actuator test. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the PCI data bus and
the data bus message inputs to the EMIC that con-
trol the VFD functions requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation. Specific operation details for the odometer
and trip odometer functions of the VFD may be found
elsewhere in this service information.
INDICATORS
Indicators are located in various positions within
the EMIC and are all connected to the EMIC circuit
board. The turn signal indicators are hard wired. The
brake indicator is controlled by PCI data bus mes-
sages from the Controller Antilock Brake (CAB) as
well as by hard wired park brake switch and brake
fluid level switch inputs to the EMIC. The Malfunc-
tion Indicator Lamp (MIL) is normally controlled by
PCI data bus messages from the Powertrain Control
Module (PCM); however, if the EMIC loses PCI data
bus communication, the EMIC circuitry will automat-
ically turn the MIL on until PCI data bus communi-
cation is restored. The EMIC uses PCI data bus
messages from the Airbag Control Module (ACM), the
BCM, the PCM, the CAB, the Sentry Key Immobi-
lizer Module (SKIM), and the Transmission Control
Module (TCM) to control all of the remaining indica-
tors.
The various indicators are controlled by different
strategies; some receive fused ignition switch output
from the EMIC circuitry and have a switched ground,
others are grounded through the EMIC circuitry and
have a switched battery feed, while still others are
completely controlled by the EMIC microprocessor
based upon various hard wired and electronic mes-
sage inputs. Some indicators are illuminated at a
fixed intensity, while the illumination intensity of
others is synchronized with that of the EMIC general
illumination lamps.
The hard wired indicators are diagnosed using con-
ventional diagnostic methods. The EMIC and PCI
bus message controlled indicators are diagnosed
using the EMIC self-diagnostic actuator test. (Refer
to 8 - ELECTRICAL/INSTRUMENT CLUSTER -
DIAGNOSIS AND TESTING). Proper testing of the
PCI data bus and the electronic data bus message
inputs to the EMIC that control each indicator
require the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information. Specific details of
the operation for each indicator may be found else-
where in this service information.CLUSTER ILLUMINATION
Two types of general cluster illumination are avail-
able in this model. Base versions of the EMIC have
several incandescent illumination lamps, while pre-
mium versions of the EMIC have a single electro-lu-
minescent lamp. Both types of lamps provide cluster
back lighting whenever the exterior lighting is
turned On with the control knob on the left (lighting)
multi-function switch control stalk. The illumination
intensity of these lamps is adjusted by the EMIC
microprocessor based upon electronic dimming level
messages received from the Body Control Module
(BCM) over the PCI data bus. The BCM provides
electronic dimming level messages to the EMIC
based upon internal programming and inputs it
receives when the control ring on the left (lighting)
multi-function switch control stalk is rotated (down
to dim, up to brighten) to one of six available minor
detent positions.
The incandescent illumination lamps receive bat-
tery current at all times, while the ground for these
lamps is controlled by a 12-volt Pulse Width Modu-
lated (PWM) output of the EMIC electronic circuitry.
The illumination intensity of these bulbs and of the
vacuum-fluorescent electronic display are controlled
by the instrument cluster microprocessor based upon
dimming level messages received from the Body Con-
trol Module (BCM) over the PCI data bus. The BCM
uses inputs from the headlamp and panel dimmer
switches within the left (lighting) multi-function
switch control stalk and internal programming to
decide what dimming level message is required. The
BCM then sends the proper dimming level messages
to the EMIC over the PCI data bus.
The electro-luminescent lamp unit consists of lay-
ers of phosphor, carbon, idium tin oxide, and dielec-
tric applied by a silk-screen process between two
polyester membranes and includes a short pigtail
wire and connector. The lamp pigtail wire is con-
nected to a small connector receptacle on the EMIC
circuit board through a small clearance hole in the
cluster housing rear cover. The EMIC electronic cir-
cuitry also uses a PWM strategy to control the illu-
mination intensity of this lamp; however, the EMIC
powers this lamp with an Alternating Current (AC)
rated at 80 volts rms (root mean squared) and 415
Hertz, which excites the phosphor particles causing
them to luminesce.
The BCM also has several hard wired panel lamp
driver outputs and sends the proper panel lamps
dimming level messages over the PCI data bus to
coordinate the illumination intensity of all of the
instrument panel lighting and the VFDs of other
electronic modules on the PCI data bus. Vehicles
equipped with the Auto Headlamps option have an
automatic parade mode. In this mode, the BCM uses
8J - 6 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)

SHIFT INDICATOR (TRANSFER
CASE)
DESCRIPTION
A part time indicator is standard equipment on all
instrument clusters, but is only functional on vehi-
cles equipped with the standard equipment Selec-
Trac four-wheel drive system. The part time indicator
is located near the right edge of the instrument clus-
ter, to the right of the speedometer. The part time
indicator consists of the words ªPART TIMEº
imprinted on an amber lens. The lens is located
behind a cutout in the opaque layer of the instru-
ment cluster overlay. The dark outer layer of the
overlay prevents the indicator from being clearly vis-
ible when it is not illuminated. The words ªPART
TIMEº appear silhouetted against an amber field
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by a
replaceable incandescent bulb and bulb holder unit
located on the instrument cluster electronic circuit
board. The part time indicator lens is serviced as a
unit with the instrument cluster lens, hood and mask
unit.
OPERATION
The part time indicator gives an indication to the
vehicle operator that a four-wheel drive part time
operating mode of the transfer case is selected. On
vehicles with the standard equipment Selec-Trac
four-wheel drive system, the part time indicator illu-
minates when the NV-242 transfer case is engaged in
either the4X4Part Time or 4 Lo positions. This
indicator is controlled by a transistor on the instru-
ment cluster electronic circuit board based upon clus-
ter programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The part time indicator
bulb is completely controlled by the instrument clus-
ter logic circuit, and that logic will only allow this
indicator to operate when the instrument cluster
receives a battery current input on the fused ignition
switch output (run-start) circuit. Therefore, the indi-
cator will always be off when the ignition switch is in
any position except On or Start. The bulb only illu-
minates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the part time indicator for the following
reasons:
²Part Time Indicator Lamp-On Message-
Each time the cluster receives a part time indicator
lamp-on message from the PCM indicating that a
four-wheel drive part time position of the transfer
case has been selected, the part time indicator will beilluminated. The indicator remains illuminated until
the cluster receives a part time indicator lamp-off
message from the PCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the part time indicator will
be turned on for the duration of the test to confirm
the functionality of the bulb and the cluster control
circuitry.
The PCM continually monitors the transfer case
switch to determine the driveline operating mode.
The PCM then sends the proper part time indicator
lamp-on and lamp-off messages to the instrument
cluster. If the part time indicator fails to light during
the actuator test, replace the bulb with a known good
unit. For further diagnosis of the part time indicator
or the instrument cluster circuitry that controls the
indicator, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). For
proper diagnosis of the transfer case switch, the
PCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the part
time indicator, a DRBIIItscan tool is required. Refer
to the appropriate diagnostic information.
SKIS INDICATOR
DESCRIPTION
A Sentry Key Immobilizer System (SKIS) indicator
is standard equipment on all instrument clusters, but
is only operational on vehicles equipped with the
optional SKIS. The SKIS indicator is located in the
upper right corner of the instrument cluster, to the
right of the speedometer. The SKIS indicator consists
of a graphical representation or icon of a circled and
crossed-out key imprinted on an amber lens. The lens
is located behind a cutout in the opaque layer of the
instrument cluster overlay. The dark outer layer of
the overlay prevents the indicator from being clearly
visible when it is not illuminated. The icon appears
silhouetted against an amber field through the trans-
lucent outer layer of the overlay when it is illumi-
nated from behind by an incandescent bulb and bulb
holder unit located on the instrument cluster elec-
tronic circuit board. The SKIS indicator lens is ser-
viced as a unit with the instrument cluster lens, hood
and mask unit.
OPERATION
The Sentry Key Immobilizer System (SKIS) indica-
tor gives an indication to the vehicle operator of the
status of the SKIS. This indicator is controlled by a
transistor on the instrument cluster electronic circuit
board based upon cluster programming and elec-
tronic messages received by the cluster from the Sen-
try Key Immobilizer Module (SKIM) over the
WJINSTRUMENT CLUSTER 8J - 29

Programmable Communications Interface (PCI) data
bus. The SKIS indicator bulb is completely controlled
by the instrument cluster logic circuit, and that logic
will only allow this indicator to operate when the
instrument cluster receives a battery current input
on the fused ignition switch output (run-start) cir-
cuit. Therefore, the indicator will always be off when
the ignition switch is in any position except On or
Start. The bulb only illuminates when it is switched
to ground by the instrument cluster transistor. The
instrument cluster will turn on the SKIS indicator
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 SKIS indicator for about three sec-
onds as a bulb test.
²SKIS Indicator Lamp-On Message- Each
time the cluster receives a SKIS indicator lamp-on
message from the SKIM, the SKIS indicator will be
illuminated. The indicator can be flashed on and off,
or illuminated solid, as dictated by the SKIM mes-
sage. For more information on the SKIS and the
SKIS indicator control parameters, (Refer to 8 -
ELECTRICAL/VEHICLE THEFT SECURITY -
OPERATION). The indicator remains illuminated
until the cluster receives a SKIS indicator lamp-off
message from the SKIM, or until the ignition switch
is turned to the Off position, whichever occurs first.
²Communication Error- If the cluster receives
no SKIS indicator lamp-on or lamp-off messages from
the SKIM for twenty consecutive seconds, the SKIS
indicator is illuminated by the instrument cluster.
The indicator remains controlled and illuminated by
the cluster until a valid SKIS indicator lamp-on or
lamp-off message is received from the SKIM.
²Actuator Test- Each time the cluster is put
through the actuator test, the SKIS indicator will be
turned on for the duration of the test to confirm the
functionality of the bulb and the cluster control cir-
cuitry.
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
and whether a valid key is present in the ignition
lock cylinder. The SKIM then sends the proper SKIS
indicator lamp-on or lamp-off messages to the instru-
ment cluster. If the SKIS indicator fails to light dur-
ing the bulb test, replace the bulb with a known good
unit. For further diagnosis of the SKIS indicator or
the instrument cluster circuitry that controls the
indicator, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). If the
instrument cluster flashes the SKIS indicator upon
ignition On, or turns on the SKIS indicator solid
after the bulb test, it indicates that a SKIS malfunc-
tion has occurred or that the SKIS is inoperative. Forproper diagnosis of the SKIS, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the SKIS indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
SPEEDOMETER
DESCRIPTION
A speedometer is standard equipment on all instru-
ment clusters. The speedometer is located to the
right of the tachometer in the instrument cluster.
The speedometer consists of a movable gauge needle
or pointer controlled by the instrument cluster cir-
cuitry, and a fixed 255 degree primary scale on the
gauge dial face that reads left-to-right either from 0
to 120 mph, from 0 to 200 km/h, or from 0 to 220
km/h, depending upon the market for which the vehi-
cle is manufactured. Most models also have a smaller
secondary inner scale on the gauge dial face that pro-
vides the equivalent opposite measurement units
from the primary scale. Text appearing in the center
of the gauge dial face just beneath the hub of the
speedometer needle abbreviates the unit of measure
for the primary scale in all upper case letters (i.e.:
MPH or KM/H). On models with a secondary scale,
the abbreviation for that scale follows the abbrevia-
tion for the primary scale in all lower case letters
(i.e.: mph or km/h).
The speedometer graphics are either white, gray
and orange against a black gauge dial face (base
cluster) or black and gray against a taupe gauge dial
face (premium cluster), making them clearly visible
within the instrument cluster in daylight. When illu-
minated from behind by the panel lamps dimmer
controlled cluster illumination lighting with the exte-
rior lamps turned On, the base cluster white gauge
graphics appear blue-green and the orange graphics
still appear orange, while the premium cluster taupe
gauge dial face appears blue-green with the black
graphics silhouetted against the illuminated back-
ground. The gray gauge graphics for both versions of
the cluster are not illuminated. The orange gauge
needle in the base cluster gauge is internally illumi-
nated, while the black gauge needle in the premium
cluster gauge is not.
Base cluster gauge illumination is provided by
replaceable incandescent bulb and bulb holder units
located on the instrument cluster electronic circuit
board. Premium cluster gauge illumination is pro-
vided by an integral electro-luminescent lamp that is
serviced as a unit with the instrument cluster. The
speedometer is serviced as a unit with the instru-
ment cluster.
8J - 30 INSTRUMENT CLUSTERWJ
SKIS INDICATOR (Continued)