2003 JEEP GRAND CHEROKEE oil system

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)

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)

switch is turned to the Off position, whichever occurs
first.
²Actuator Test- Each time the cluster is put
through the actuator test, the transmission over-tem-
perature 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 or TCM continually monitors the trans-
mission temperature sensor to determine the trans-
mission operating condition. The PCM or TCM then
sends the proper trans over-temp indicator lamp-on
or lamp-off messages to the instrument cluster. If the
transmission over-temperature indicator fails to light
during the bulb test, replace the bulb with a known
good unit. If the instrument cluster turns on the
transmission over-temperature indicator due to a
high transmission oil temperature condition, it may
indicate that the transmission or the transmission
cooling system are being overloaded or that they
require service. For further diagnosis of the trans-
mission over-temperature indicator or the instrument
cluster circuitry that controls the indicator, (Refer to
8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAG-
NOSIS AND TESTING). For proper diagnosis of the
transmission temperature sensor, the PCM, the
TCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the
transmission over-temperature indicator, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
TURN SIGNAL INDICATOR
DESCRIPTION
Two turn signal indicators, one right and one left,
are standard equipment on all instrument clusters.
The turn signal indicators are located near the upper
edge of the instrument cluster, the left one is left of
the tachometer, and the right one is right of the
speedometer. Each turn signal indicator consists of
an International Control and Display Symbol icon for
ªTurn Warningº imprinted on a green lens. Each lens
is located behind a dedicated cutout in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents these icons from
being clearly visible when they are not illuminated.
The icons appear silhouetted against a green 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 turn signal indicator lenses are serviced
as a unit with the instrument cluster lens, hood and
mask unit.
OPERATION
The turn signal indicators give an indication to the
vehicle operator that the turn signal (left or right
indicator flashing) or hazard warning (both left and
right indicators flashing) have been selected and are
operating. These indicators are controlled by two
individual hard wired inputs from the combination
flasher circuitry to the instrument cluster electronic
circuit board. Each turn signal indicator bulb is
grounded on the instrument cluster electronic circuit
board at all times; therefore, these indicators remain
functional regardless of the ignition switch position.
Each indicator bulb will only illuminate when it is
provided with battery current by the combination
flasher in the Junction Block (JB).
The turn signal indicators are connected in parallel
with the other turn signal circuits. This arrangement
allows the turn signal indicators to remain func-
tional, regardless of the condition of the other cir-
cuits in the turn signal and hazard warning systems.
The combination flasher outputs to the instrument
cluster turn signal indicator inputs can be diagnosed
using conventional diagnostic tools and methods. For
more information on the turn signal and hazard
warning system, (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR - OPERATION - TURN
SIGNAL & HAZARD WARNING SYSTEM).
DIAGNOSIS AND TESTING - TURN SIGNAL
INDICATOR
The diagnosis found here addresses an inoperative
turn signal indicator condition. If the problem being
diagnosed is related to inoperative turn signal or
hazard warning lamps, be certain to repair the turn
signal and hazard warning system before attempting
to diagnose or repair the turn signal indicators.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR - DIAGNOSIS AND TESTING - TURN
SIGNAL & HAZARD WARNING SYSTEM). If no
turn signal and hazard warning system problem is
found, the following procedure will help locate an
open in the turn signal indicator circuit. Refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector 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.
WJINSTRUMENT CLUSTER 8J - 33
TRANS TEMP INDICATOR (Continued)

INSTALLATION - BULB
CAUTION: Do not touch the bulb glass with fingers
or other oily surfaces. Reduced bulb life will result.
(1) Position the bulb into socket and push into
place.
(2) Position the bulb socket in headlamp and turn
the bulb socket one quarter turn clockwise.
(3) Install the headlamp.
HEADLAMP SWITCH
DESCRIPTION
The headlamp switch is part of the left multi-func-
tion switch. A knob on the end of the multi-function
switch control stalk controls all of the exterior light-
ing switch functions. The exterior lighting switch is
hard wired to the Body Control Module (BCM).
The exterior lighting switch cannot be adjusted or
repaired and, if faulty or damaged, the entire left
multi-function switch unit must be replaced. (Refer
to 8 - ELECTRICAL/LAMPS/LIGHTING - EXTERI-
OR/TURN SIGNAL/HAZARD SWITCH - REMOVAL)
for the service procedures. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/BODY
CONTROL/CENTRAL TIMER MODUL - DESCRIP-
TION) for more information on this component.
OPERATION
The exterior lighting switch uses a hard wired five
volt reference circuit from the BCM, resistor multi-
plexing and a hard wired switch output circuit to
provide the BCM with a zero to five volt signal thatindicates the status of all of the exterior lighting
switch settings. The BCM then uses control outputs
to energize the headlamp and park lamp relays that
activate the exterior lighting circuits.
The BCM monitors the exterior lighting switch sta-
tus, then sends the proper switch status messages to
other modules over the Programmable Communica-
tions Interface (PCI) data bus network. The exterior
lighting switch status is also used by the BCM as an
input for chime warning system operation.
DIAGNOSIS AND TESTING Ð HEADLAMP
SWITCH
Before testing the headlamp switch, turn on the
exterior lighting and open the driver side front door.
If the exterior lamps of the vehicle operate, but there
is no chime warning issued with the driver side front
door open, (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - INTERIOR/DOOR AJAR SWITCH -
DIAGNOSIS AND TESTING). If the exterior lamps
of the vehicle are inoperative, but the chime warning
is issued, (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR - DIAGNOSIS AND TESTING).
If the exterior lamps and the chime warning are
both inoperative, test the left multi-function switch.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR - DIAGNOSIS AND TESTING). If the
multi-function switch tests OK, proceed as follows.
The following tests will help to locate a short or open
in the hard wired circuits between the multi-function
switch and the Body Control Module (BCM). For
complete circuit diagrams, refer to the appropriate
wiring information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector from the left multi-function switch connec-
tor. Disconnect the instrument panel wire harness
connector from the Body Control Module (BCM).
Check for continuity between the headlamp switch
mux circuit of the instrument panel wire harness
connector for the multi-function switch and a good
ground. There should be no continuity. If OK, go to
Step 2. If not OK, repair the shorted headlamp
switch mux circuit.
(2) Check for continuity between the headlamp
switch mux circuit of the instrument panel wire har-
Fig. 13 Headlamp Bulb
1 - HIGH BEAM BULB
2 - LOW BEAM BULB
3 - MARKER BULB
4 - PARK/TURN SIGNAL BULB
WJLAMPS/LIGHTING - EXTERIOR 8L - 15
HEADLAMP (Continued)

The RKE system includes two transmitters when
the vehicle is shipped from the factory, but the sys-
tem can retain the vehicle access codes of up to four
transmitters. The transmitter codes are retained in
the RKE receiver memory, even if the battery is dis-
connected. If an RKE transmitter is faulty or lost,
new transmitter vehicle access codes can be pro-
grammed into the system using a DRBIIItscan tool
and the appropriate diagnostic information.
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 8 - ELECTRICAL/OVERHEAD CON-
SOLE/ELECTRONIC VEHICLE INFO CENTER -
DESCRIPTION). Customer programmable feature
options affecting the RKE system include:
²Remote Unlock- Allows the option of having
only the driver side front door unlock when the RKE
transmitter Unlock button is depressed the first time
and the remaining doors and the liftgate unlock
when the button is depressed a second time, or hav-
ing all doors and the liftgate unlock upon the first
depression of the RKE transmitter Unlock button.
²Remote Linked to Memory- If the vehicle is
equipped with the Memory System, this feature
allows the option of having the RKE transmitter
Unlock button activate the recall of the stored set-
tings, or having the recall function assigned solely to
the memory switch on the driver side front door trim
panel.
²Sound Horn on Lock- Allows the option of
having the horn sound a short chirp as an audible
verification that the doors have locked, or having no
audible verification.
²Flash Lights with Lock- Allows the option of
having the lights flash as an optical verification that
the doors have locked, or having no optical verifica-
tion.
This group covers the following components of the
RKE system:
²RKE Receiver
²RKE Transmitter
Certain functions and features of the RKE 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 DRBIIItscan
tool and the appropriate diagnostic information are
required.The other electronic modules that may affect RKE
system operation are as follows:
²Body Control Module (BCM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/BODY CONTROL/CENTRAL TIMER MOD-
ULE - DESCRIPTION).
²Driver Door Module (DDM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DOOR MODULE - DESCRIPTION).
²Electronic Vehicle Information Center
(EVIC)- (Refer to 8 - ELECTRICAL/OVERHEAD
CONSOLE/ELECTRONIC VEHICLE INFO CENTER
- DESCRIPTION).
²Passenger Door Module (PDM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DOOR MODULE - DESCRIPTION).
²Powertrain Control Module (PCM)- (Refer
to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION).
Hard wired circuitry connects the RKE system
components via the PDM to the electrical system of
the vehicle. These hard wired circuits are integral to
several wire harnesses, which are routed throughout
the vehicle and retained by many different methods.
These circuits may be connected to each other, to the
vehicle electrical system and to the RKE system com-
ponents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. 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
harness connectors, splices and grounds.
COMBINATION FLASHER
The combination flasher is a smart relay that func-
tions as both the turn signal system and the hazard
warning system flasher. The combination flasher con-
tains active electronic Integrated Circuitry (IC) ele-
ments. This flasher can be energized by the BCM to
flash all of the park/turn signal/front side marker
lamps as an optical alert for the RKE panic function
and, if the Flash Lights with Lock programmable fea-
ture is enabled, as an optical verification for the RKE
lock event. (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR/COMBINATION FLASHER
- DESCRIPTION).
HORN RELAY
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) in
WJPOWER LOCKS 8N - 3
POWER LOCKS (Continued)

the engine compartment. This relay can be energized
by the BCM to sound the horns as an audible alert
for the RKE panic function and, if the Sound Horn
on Lock programmable feature is enabled, as an
audible verification for the RKE lock event. (Refer to
8 - ELECTRICAL/HORN/HORN RELAY - DESCRIP-
TION).
LOW BEAM HEADLAMP RELAY
The low beam headlamp relay is a electromechan-
ical device that switches battery current to the head-
lamp low beams when the BCM grounds the relay
coil. The low beam headlamp relay is located in the
junction block in the passenger compartment. This
relay can be energized by the BCM to flash the head-
lamp low beams as an optical alert for the RKE panic
function. (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR/HEADLAMP - DESCRIPTION).
DESCRIPTION - LIFTGATE FLIP-UP GLASS
POWER RELEASE SYSTEM
A power operated liftgate flip-up glass release sys-
tem is standard factory installed equipment on this
model. The liftgate flip-up glass power release system
allows the flip-up glass latch to be released electri-
cally by depressing a switch located on the bottom of
the liftgate license plate lamp housing unit, above
the license plate on the outside of the liftgate.
The liftgate flip-up glass release system operates
on non-switched battery current supplied through a
fuse in the junction block so that the system remains
functional, regardless of the ignition switch position.
However, a limit switch that is integral to the liftgate
latch actuator unit opens to prevent the flip-up glass
latch from being actuated when the liftgate latch is
locked.
The liftgate flip-up glass power release system
includes the following components:
²Liftgate Flip-Up Glass Limit Switch- The
liftgate flip-up glass limit switch is integral to the
liftgate latch unit. (Refer to 23 - BODY/DECKLID/
HATCH/LIFTGATE/TAILGATE/LATCH - REMOVAL)
and (Refer to 23 - BODY/DECKLID/HATCH/LIFT-
GATE/TAILGATE/LATCH - INSTALLATION).
²Liftgate Flip-Up Glass Release Motor- The
liftgate flip-up glass release motor is integral to the
liftgate flip-up glass latch unit. (Refer to 23 - BODY/
DECKLID/HATCH/LIFTGATE/TAILGATE/FLIP-UP
GLASS LATCH - REMOVAL) and (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
FLIP-UP GLASS LATCH - INSTALLATION).
²Liftgate Flip-Up Glass Release Switch- The
liftgate flip-up glass release switch is integral to the
liftgate license plate lamp housing. (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
FLIP-UP GLASS SWITCH - REMOVAL) and (Referto 23 - BODY/DECKLID/HATCH/LIFTGATE/TAIL-
GATE/FLIP-UP GLASS SWITCH - INSTALLATION).
Hard wired circuitry connects the liftgate flip-up
glass power release system components to the electri-
cal system of the vehicle. These hard wired circuits
are integral to several wire harnesses, which are
routed throughout the vehicle and retained by many
different methods. These circuits may be connected to
each other, to the vehicle electrical system and to the
liftgate flip-up glass power release system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. 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
harness connectors, splices and grounds.OPERATION
OPERATION - POWER LOCK SYSTEM
The Passenger Door Module (PDM) contains the
power door lock control logic and a power lock switch.
The Driver Door Module (DDM) contains a power
lock switch and controls the output to the driver side
front door power lock motor, while the PDM controls
the output to the power lock motors for the remain-
ing doors and the liftgate.
When the power lock switch on the DDM is used to
lock or unlock the doors, the DDM sends a control
output to the driver side front door power lock motor
and sends lock or unlock request messages to the
PDM over the Programmable Communications Inter-
face (PCI) data bus. The PDM responds to these mes-
sages by sending control outputs to the power lock
motors of the remaining doors and the liftgate. When
the power lock switch on the PDM is used to lock or
unlock the doors, the PDM sends control outputs to
the power lock motors in the passenger side front
door, both rear doors and the liftgate, then sends lock
or unlock request messages to the DDM over the Pro-
grammable Communications Interface (PCI) data
bus. The DDM responds to these messages by send-
ing control outputs to the power lock motor of the
driver side front door.
In order to support the auto door locks and unlock
on exit features, if enabled, the power lock system
logic in the PDM needs to know the door ajar switch
status, vehicle speed, and transmission gear selector
lever position. The passenger side front door ajar
switch is the only hard wired input to the PDM. The
PDM obtains the remaining information from mes-
sages it receives from other electronic modules over
the PCI data bus network.
8N - 4 POWER LOCKSWJ
POWER LOCKS (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)