2003 JEEP GRAND CHEROKEE Oil pressure switch

not attach the wire harness connectors until the cur-
ing process is complete.
(11) Check the operation of the rear glass heating
grid.
REAR WINDOW DEFOGGER
RELAY
DESCRIPTION
The rear window defogger relay is an electrome-
chanical device that switches fused battery current to
the rear glass heating grid and the Light-Emitting
Diode (LED) indicator of the rear window defogger
switch, when the Body Control Module (BCM) rear
window defogger timer and logic circuitry grounds
the relay coil. The rear window defogger relay is
located in the junction block, under the left end of
the instrument panel in the passenger compartment.
The rear window defogger relay is a International
Standards Organization (ISO) relay. Relays conform-
ing to the ISO specifications have common physical
dimensions, current capacities, terminal patterns,
and terminal functions.
The rear window defogger relay cannot be repaired
or adjusted and, if faulty or damaged, it must be
replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER RELAY
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 AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
RELAY TEST
The rear window defogger relay (Fig. 4) is located
in the junction block, under the left end of the instru-
ment panel in the passenger compartment. Remove
the rear window defogger relay from the junction
block to perform the following tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   10 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, refer to theRelay Circuit Test.If
not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
fused B(+) circuit to the Power Distribution Center
(PDC) fuse as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
Fig. 4 REAR WINDOW DEFOGGER RELAY
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
WJHEATED GLASS 8G - 5
REAR WINDOW DEFOGGER GRID (Continued)

(6) Remove both horns and the mounting bracket
from the right extension of the radiator closure
assembly as a unit.
INSTALLATION
(1) Position both horns and the mounting bracket
onto the right extension of the radiator closure
assembly as a unit.
(2) Install and tighten the screw that secures the
horn mounting bracket to the right extension of the
radiator closure assembly. Tighten the screw to 11.3
N´m (100 in. lbs.).
(3) Reconnect the two right headlamp and dash
wire harness connectors to the horn connector recep-
tacles. Be certain to engage the connector lock tabs
after reconnecting them to the horn connector recep-
tacles.
(4) Install the lower front half of the inner liner to
the right front fender wheel house. (Refer to 23 -
BODY/EXTERIOR/FRONT FENDER - INSTALLA-
TION) for the procedure.
(5) Lower the vehicle.
(6) Reconnect the battery negative cable.
HORN RELAY
DESCRIPTION
The horn relay is a electromechanical device that
switches battery current to the horn when the horn
switch grounds the relay coil. The horn relay is
located in the Power Distribution Center (PDC) inthe engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location.
The horn relay is a International Standards Orga-
nization (ISO) micro-relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The ISO micro-relay terminal functions
are the same as a conventional ISO relay. However,
the ISO micro-relay terminal pattern (or footprint) is
different, the current capacity is lower, and the phys-
ical dimensions are smaller than those of the conven-
tional ISO relay.
The horn relay cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
DIAGNOSIS AND TESTING - HORN RELAY
The horn relay (Fig. 2) is located in the Power Dis-
tribution Center (PDC) between the battery and the
right inner fender shield on the passenger side of the
engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location. For complete circuit diagrams, refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
Fig. 1 Horns Remove/Install
1 - RADIATOR CLOSURE ASSEMBLY
2 - HORNS AND MOUNTING BRACKET
3 - RIGHT HEADLAMP AND DASH WIRE HARNESS
CONNECTORS
8H - 4 HORNWJ
HORN (Continued)

OPERATION
The ElectroMechanical Instrument Cluster (EMIC)
is designed to allow the vehicle operator to monitor
the conditions of many of the vehicle components and
operating systems. The gauges and indicators in the
EMIC provide valuable information about the various
standard and optional powertrains, fuel and emis-
sions systems, cooling systems, lighting systems,
safety systems and many other convenience items.
The EMIC is installed in the instrument panel so
that all of these monitors can be easily viewed by the
vehicle operator when driving, while still allowing
relative ease of access for service. The microproces-
sor-based EMIC hardware and software uses various
inputs to control the gauges and indicators visible on
the face of the cluster. Some of these inputs are hard
wired, but most are in the form of electronic mes-
sages that are transmitted by other electronic mod-ules over the Programmable Communications
Interface (PCI) data bus network. (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/COMMUNICATION - OPERATION).
The EMIC microprocessor smooths the input data
using algorithms to provide gauge readings that are
accurate, stable and responsive to operating condi-
tions. These algorithms are designed to provide
gauge readings during normal operation that are con-
sistent with customer expectations. However, when
abnormal conditions exist, such as low or high bat-
tery voltage, low oil pressure or high coolant temper-
ature, the algorithm can drive the gauge pointer to
an extreme position and the microprocessor turns on
the Check Gauges indicator to provide a distinct
visual indication of a problem to the vehicle operator.
The instrument cluster circuitry also sends electronic
chime tone request messages over the PCI data bus
to the Body Control Module (BCM) when it monitors
Fig. 2 EMIC Gauges & Indicators
1 - BRAKE INDICATOR 15 - TRANSMISSION OVERTEMP INDICATOR
2 - REAR FOG LAMP INDICATOR 16 - PART TIME 4WD INDICATOR
3 - WATER-IN-FUEL INDICATOR 17 - CHECK GAUGES INDICATOR
4 - VOLTAGE GAUGE 18 - ENGINE TEMPERATURE GAUGE
5 - LEFT TURN INDICATOR 19 - ODOMETER/TRIP ODOMETER SWITCH BUTTON
6 - TACHOMETER 20 - ODOMETER/TRIP ODOMETER DISPLAY
7 - HIGH BEAM INDICATOR 21 - WAIT-TO-START INDICATOR
8 - AIRBAG INDICATOR 22 - OVERDRIVE-OFF INDICATOR
9 - SPEEDOMETER 23 - SEATBELT INDICATOR
10 - RIGHT TURN INDICATOR 24 - ABS INDICATOR
11 - OIL PRESSURE GAUGE 25 - FUEL GAUGE
12 - SKIS INDICATOR 26 - FRONT FOG LAMP INDICATOR
13 - MALFUNCTION INDICATOR LAMP (MIL) 27 - LOW FUEL INDICATOR
14 - CRUISE INDICATOR 28 - COOLANT LOW INDICATOR
8J - 4 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)

lens is serviced as a unit with the instrument cluster
lens, hood and mask unit.
OPERATION
The check gauges indicator gives an indication to
the vehicle operator when certain instrument cluster
gauge readings reflect a condition requiring immedi-
ate attention. This indicator is controlled by a tran-
sistor on the instrument cluster circuit board based
upon cluster programming and electronic messages
received by the cluster from the Powertrain Control
Module (PCM) over the Programmable Communica-
tions Interface (PCI) data bus. The check gauges
indicator Light Emitting Diode (LED) 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 cur-
rent input on the fused ignition switch output (run-
start) circuit. Therefore, the indicator will always be
off when the ignition switch is in any position except
On or Start. The LED only illuminates when it is
provided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
check gauges indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the check gauges indicator
is illuminated for about three seconds as a bulb test.
²Engine Temperature High/Critical Message
- Each time the cluster receives a message from the
PCM indicating the engine coolant temperature is
high or critical [above about 127É C (261É F) for gas-
oline engines except Gulf Coast Country (GCC), 129É
C (264É F) for GCC gasoline engines, and 118É C
(244É F) for diesel engines], the check gauges indica-
tor is illuminated. The indicator remains illuminated
until the cluster receives a message indicating the
engine coolant temperature is not high or critical
[about 125É C (255É F) or below for all gasoline
engines, or 115É C (239É F) for all diesel engines].
²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is about 0.28
kg/cm or lower (about 4 psi or lower), the check
gauges indicator is illuminated. The indicator
remains illuminated until the cluster receives a mes-
sage from the PCM indicating that the engine oil
pressure is about 0.56 kg/cm or higher (about 8 psi
or higher). The cluster will only turn the indicator on
in response to an engine oil pressure low message if
the ignition switch is in the On position and the
engine speed is 300 rpm or greater.
²System Voltage Low Message- Each time the
cluster receives a message from the PCM indicating
a low system voltage condition (system voltage is
about eleven volts or lower), the check gauges indica-
tor is illuminated. The indicator remains illuminateduntil the cluster receives a message from the PCM
indicating there is no low system voltage condition
(system voltage is above about eleven volts, but lower
than about sixteen volts).
²System Voltage High Message- Each time
the cluster receives a message from the PCM indicat-
ing a high system voltage condition (system voltage
is about sixteen volts or higher), the check gauges
indicator is illuminated. The indicator remains illu-
minated until the cluster receives a message from
the PCM indicating there is no high system voltage
condition (system voltage is below about sixteen
volts, but higher than about eleven volts).
²Actuator Test- Each time the cluster is put
through the actuator test, the check gauges indicator
will be turned on for the duration of the test to con-
firm the functionality of the LED and the cluster con-
trol circuitry.
The PCM continually monitors the engine temper-
ature, oil pressure, and electrical system voltage,
then sends the proper messages to the instrument
cluster. For further diagnosis of the check gauges
indicator or the instrument cluster circuitry that con-
trols the indicator, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the PCM, the PCI
data bus, or the electronic message inputs to the
instrument cluster that control the check gauges
indicator, a DRBIIItscan tool is required. Refer to
the appropriate diagnostic information.
COOLANT LOW INDICATOR
DESCRIPTION
A coolant low indicator is only found in the instru-
ment clusters of vehicles equipped with an optional
diesel engine. The coolant low indicator should not be
confused with the coolant level low indication pro-
vided by the Electronic Vehicle Information Center
(EVIC) of vehicles equipped with a gasoline engine,
although they do perform the same function. The
coolant low indicator is located in the lower left cor-
ner of the instrument cluster, to the left of the
tachometer. The coolant low indicator consists of an
International Control and Display Symbol icon for
ªLow Coolantº 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 the indicator
is illuminated from behind by a replaceable incandes-
cent bulb and bulb holder unit located on the instru-
ment cluster electronic circuit board. When the
WJINSTRUMENT CLUSTER 8J - 17
CHECK GAUGES INDICATOR (Continued)

nated at full brightness if the exterior lamps are
turned On during daylight hours.
The VFD, the trip odometer switch, and the trip
odometer switch button are serviced as a unit with
the instrument cluster.
OPERATION
The odometer and trip odometer give an indication
to the vehicle operator of the distance the vehicle has
traveled. This gauge is controlled by the instrument
cluster electronic circuitry based upon cluster pro-
gramming and electronic messages received by the
cluster from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus. The odometer and trip odometer
information is displayed by the instrument cluster
Vacuum Fluorescent Display (VFD). The VFD will
only display odometer or trip odometer information
after the ignition switch is turned to the On or Start
positions, and will display the information in the
odometer or trip odometer mode based upon the
selection that was active when the ignition switch
was last turned to the Off position. The instrument
cluster circuitry controls the VFD and provides the
following features:
²Odometer/Trip Odometer Display Toggling-
Actuating the trip odometer reset switch button
momentarily with the ignition switch in the On posi-
tion will toggle the display between the odometer and
trip odometer information. Each time the ignition
switch is turned to the On or Start positions, the dis-
play will automatically return to the last mode
selected (odometer or trip odometer) before the igni-
tion switch was turned to the Off position.
²Trip Odometer Reset- When the trip odome-
ter reset switch button is depressed and held for
longer than about two seconds with the ignitions
switch in the On or Start positions, the trip odometer
will be reset to 000.0 kilometers (miles). The VFD
must be displaying the current trip odometer infor-
mation in order for the trip odometer information to
be reset.
²Communication Error- If the cluster fails to
receive a distance message during normal operation,
it will hold and display the last data received until
the ignition switch is turned to the Off position. If
the cluster does not receive a distance message
within one second after the ignition switch is turned
to the On position, it will display the last distance
message stored in the cluster memory. If it is deter-
mined that the distance information stored in the
cluster memory is corrupt, it will display ª------º in
the VFD. If the cluster is unable to display distance
information due to an error internal to the cluster,
the VFD display will be blank.²Actuator Test- Each time the cluster is put
through the actuator test, the VFD will step sequen-
tially through a display of ª000000º through
ª999999º, then display the cluster software version
number to confirm the functionality of the VFD and
the cluster control circuitry.
The PCM continually monitors the vehicle speed
pulse information received from the vehicle speed
sensor, then sends the proper distance messages to
the instrument cluster. For further diagnosis of the
odometer/trip odometer or the instrument cluster cir-
cuitry that controls these functions, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
vehicle speed sensor, the PCM, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the odometer/trip odometer, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
OIL PRESSURE GAUGE
DESCRIPTION
An oil pressure gauge is standard equipment on all
instrument clusters. The oil pressure gauge is located
in the upper right corner of the instrument cluster, to
the right of the speedometer. The oil pressure gauge
consists of a movable gauge needle or pointer con-
trolled by the instrument cluster circuitry and a fixed
90 degree scale on the gauge dial face that reads left-
to-right from 0 kg/cm to 5.4 kg/cm (metric cluster
for gasoline engines), from 0 kg/cm to 8.3 kg/cm
(metric cluster for diesel engines), or from 0 psi to 80
psi (U.S. cluster), depending upon the market for
which the vehicle is manufactured. An International
Control and Display Symbol icon for ªEngine Oilº is
located on the gauge dial face.
The oil pressure gauge 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.
WJINSTRUMENT CLUSTER 8J - 25
ODOMETER (Continued)

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
oil pressure gauge is serviced as a unit with the
instrument cluster.
OPERATION
The oil pressure gauge gives an indication to the
vehicle operator of the engine oil pressure. This
gauge is controlled by the instrument cluster circuit
board based upon cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus. The
oil pressure gauge is an air core magnetic unit that
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (run-start) circuit whenever the igni-
tion switch is in the On or Start positions. The clus-
ter is programmed to move the gauge needle back to
the low end of the scale after the ignition switch is
turned to the Off position. The instrument cluster
circuitry controls the gauge needle position and pro-
vides the following features:
²Engine Oil Pressure Normal Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is within the nor-
mal operating range [above 0.28 kg/cm (above 4
psi), the gauge needle is moved to the relative pres-
sure position of the gauge scale.
²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is about 0.28
kg/cm or lower (about 4 psi or lower), the gauge
needle is moved to the far left (low) end of the gauge
scale. The gauge needle remains at the low end of
the scale until the cluster receives a message from
the PCM indicating that the engine oil pressure is
about 0.56 kg/cm or higher (about 8 psi or higher).
²Communication Error- If the cluster fails to
receive an engine oil pressure message, it will hold
the gauge needle at the last indication for about
twelve seconds or until a new engine oil pressure
message is received, whichever occurs first. After
twelve seconds, the cluster will return the gauge nee-
dle to the low end of the gauge scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
swept across the entire gauge scale and back in order
to confirm the functionality of the gauge and the
cluster control circuitry.
The PCM continually monitors the engine oil pres-
sure sensor to determine the engine oil pressure. ThePCM then sends the proper engine oil pressure mes-
sages to the instrument cluster. For further diagnosis
of the oil pressure gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster turns on
the check gauges indicator due to a low oil pressure
gauge reading, it may indicate that the engine or the
engine oiling system requires service. For proper
diagnosis of the engine oil pressure sensor, the PCM,
the PCI data bus, or the electronic message inputs to
the instrument cluster that control the oil pressure
gauge, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
OVERDRIVE OFF INDICATOR
DESCRIPTION
An overdrive off indicator is standard equipment
on all gasoline engine instrument clusters. The over-
drive off indicator is located in the lower edge of the
tachometer gauge dial face in the instrument cluster.
The overdrive off indicator consists of the words ªO/D
OFFº imprinted on an amber lens. The lens is
located behind a cutout in the opaque layer of the
tachometer gauge dial face overlay. The dark outer
layer of the gauge dial face overlay prevents the indi-
cator from being clearly visible when it is not illumi-
nated. The words ªO/D OFFº appear silhouetted
against an amber field through the translucent outer
layer of the gauge dial face overlay when the indica-
tor is illuminated from behind by a replaceable
incandescent bulb and bulb holder unit located on
the instrument cluster electronic circuit board. When
the exterior lighting is turned On, the illumination
intensity of the overdrive off indicator is dimmable,
which is adjusted using the panel lamps dimmer con-
trol ring on the control stalk of the left multi-func-
tion switch. The overdrive off indicator lens is
serviced as a unit with the instrument cluster.
OPERATION
The overdrive off indicator gives an indication to
the vehicle operator when the Off position of the
overdrive off switch has been selected, disabling the
electronically controlled overdrive feature of the auto-
matic transmission. This indicator is controlled by a
transistor on the instrument cluster circuit board
based upon cluster programming and electronic mes-
sages received by the cluster over the Programmable
Communications Interface (PCI) data bus. These
messages are sent by the Powertrain Control Module
(PCM) or by the Transmission Control Module
(TCM), depending on the model of the automatic
transmission. The overdrive off indicator bulb is com-
8J - 26 INSTRUMENT CLUSTERWJ
OIL PRESSURE GAUGE (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)

WASHER SYSTEM
The washer system components should be
inspected periodically, not just when washer perfor-
mance problems are experienced. This inspection
should include the following points:
(1) Check for ice or other foreign material in the
washer reservoir. If contaminated, clean and flush
the washer system. (Refer to 8 - ELECTRICAL/
FRONT WIPERS/WASHERS - CLEANING).
(2) Inspect the washer plumbing for pinched, leak-
ing, deteriorated, or incorrectly routed hoses and
damaged or disconnected hose fittings. Replace dam-
aged or deteriorated hoses and hose fittings. Leaking
washer hoses can sometimes be repaired by cutting
the hose at the leak and splicing it back together
using an in-line connector fitting. Similarly, sections
of deteriorated hose can be cut out and replaced by
splicing in new sections of hose using in-line connec-
tor fittings. Whenever routing a washer hose or a
wire harness containing a washer hose, it must be
routed away from hot, sharp, or moving parts. Also,
sharp bends that might pinch the washer hose must
be avoided.
FRONT CHECK VALVE
DESCRIPTION
A front washer system check valve is standard
equipment on this model. The front check valve is
integral to the front washer nozzle plumbing wye fit-
ting located in the cowl plenum beneath the cowl ple-
num cover/grille panel near the base of the
windshield. The check valve consists of a molded
plastic body with a round center section. Three
barbed hose nipples are formed in a wye configura-
tion on the outside circumference of the center sec-
tion of the valve body. Within the check valve body, a
small check valve operated by a small coiled spring
restricts flow through the unit until the valve is
unseated by a predetermined inlet fluid pressure.
The front check valve cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced.
OPERATION
The front check valve provides more than one func-
tion in this application. It serves as a wye connector
fitting between the cowl grille panel and washer noz-
zle sections of the front washer supply hose. It also
prevents washer fluid from draining out of the front
washer supply hoses back to the washer reservoir.
This drain-back would result in a lengthy delay from
when the front washer switch is actuated until
washer fluid was dispensed through the front washer
nozzles, because the front washer pump would have
to refill the front washer plumbing from the reservoir
to the nozzles. Finally, the front check valve prevents
washer fluid from siphoning through the front
washer nozzles after the front washer system is
turned Off. When the front washer pump pressurizes
and pumps washer fluid from the reservoir through
the front washer plumbing, the fluid pressure over-
rides the spring pressure applied to the check valve
and unseats the valve, allowing washer fluid to flow
toward the front washer nozzles. When the front
washer pump stops operating, spring pressure seats
the check valve and fluid flow in either direction
within the front washer plumbing is prevented.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the wiper arms from the wiper pivots.
(Refer to 8 - ELECTRICAL/FRONT WIPERS/WASH-
ERS/FRONT WIPER ARMS - REMOVAL).
(3) Open the hood and pull the hood to plenum
seal off of the forward flanges of the cowl grille cover
and the plenum panel.
Fig. 2 Wiper Blade Inspection
1 - WORN OR UNEVEN EDGES
2 - ROAD FILM OR FOREIGN MATERIAL DEPOSITS
3 - HARD, BRITTLE, OR CRACKED
4 - DEFORMED OR FATIGUED
5 - SPLIT
6 - DAMAGED SUPPORT COMPONENTS
WJFRONT WIPERS/WASHERS 8R - 9
FRONT WIPERS/WASHERS (Continued)