2003 JEEP GRAND CHEROKEE Prop

(6) Check for continuity between the horn switch
feed wire and the horn switch ground wire on the
driver side airbag module. There should be no conti-
nuity. If OK, go to Step 7. If not OK, replace the
faulty horn switch.
(7) Depress the center of the driver side airbag
module trim cover and check for continuity between
the horn switch feed wire and the horn switch
ground wire on the driver side airbag module. There
should now be continuity. If not OK, replace the
faulty horn switch.
REMOVAL
WARNING:
²ON VEHICLES EQUIPPED WITH AIRBAGS,
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 ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
²THE HORN SWITCH IS INTEGRAL TO THE
DRIVER SIDE AIRBAG MODULE. SERVICE OF THIS
COMPONENT SHOULD BE PERFORMED ONLY BY
CHRYSLER-TRAINED AND AUTHORIZED DEALER
SERVICE TECHNICIANS. FAILURE TO TAKE THE
PROPER PRECAUTIONS OR TO FOLLOW THE
PROPER PROCEDURES COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER AIRBAG
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the trim cover from the driver side air-
bag module. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL) for the
procedure.
(3) Remove the horn switch and tray as a unit
from the pouch on the retaining strap of the driver
side airbag module (Fig. 4).
INSTALLATION
WARNING:
²ON VEHICLES EQUIPPED WITH AIRBAGS,
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 ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.²THE HORN SWITCH IS INTEGRAL TO THE
DRIVER SIDE AIRBAG MODULE. SERVICE OF THIS
COMPONENT SHOULD BE PERFORMED ONLY BY
CHRYSLER-TRAINED AND AUTHORIZED DEALER
SERVICE TECHNICIANS. FAILURE TO TAKE THE
PROPER PRECAUTIONS OR TO FOLLOW THE
PROPER PROCEDURES COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER AIRBAG
DEPLOYMENT AND POSSIBLE OCCUPANT INJU-
RIES.
(1) Install the horn switch and tray as a unit into
the pouch on the retaining strap of the driver side
airbag module. Be certain that the tray is facing the
airbag module, that the horn switch is facing the
trim cover, that the horn switch feed wire is on the
left, and that the horn switch ground wire is on the
right.
(2) Install the trim cover onto the driver side air-
bag module. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - INSTALLATION) for
the procedure.
(3) Reconnect the battery negative cable.
Fig. 4 Horn Switch Remove/Install
1 - HORN SWITCH GROUND WIRE EYELET
2 - HORN SWITCH
3 - AIRBAG RETAINING STRAP
4 - POUCH
5 - DRIVER SIDE AIRBAG MODULE (TRIM COVER REMOVED)
6 - TRAY
7 - HORN SWITCH FEED WIRE CONNECTOR
WJHORN 8H - 7
HORN SWITCH (Continued)

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)

INSTALLATION
4.7L High-Output Engine Only
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) Thoroughly clean knock sensor mounting holes.
(2) Install sensors (Fig. 22) into cylinder block.
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. The torque for the knock senor bolt is rela-
tively light for an 8mm bolt.
NOTE: 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.
(3) Install and tighten mounting bolts.Bolt
torque is critical.Refer to torque specification.
(4) Install intake manifold. Refer to Engine sec-
tion.
(5) Connect knock sensor pigtail wiring harness to
engine wiring harness near right / rear of intake
manifold (Fig. 23).
SPARK PLUG
DESCRIPTION
Both the 4.0L 6-cylinder and the 4.7L V-8 engine
use resistor type spark plugs. Standard 4.7L V-8
engines are equipped with ªfired in suppressor sealº
type spark plugs using a copper core ground elec-
trode. High-Output (H.O.) 4.7L V-8 engines are
equipped with unique plugs using a platinum rivet
located on the tip of the center electrode.
Because of the use of an aluminum cylinder head
on the 4.7L engine, spark plug torque is very critical.
To prevent possible pre-ignition and/or mechanical
engine damage, the correct type/heat range/number
spark plug must be used.Do not substitute any
other spark plug on the 4.7L H.O. engine. Seri-
ous engine damage may occur.
Plugs on both engines have resistance values rang-
ing from 6,000 to 20,000 ohms (when checked with at
least a 1000 volt spark plug tester).Do not use an
ohmmeter to check the resistance values of thespark plugs. Inaccurate readings will result.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. A sin-
gle plug displaying an abnormal condition indicates
that a problem exists in the corresponding cylinder.
Replace spark plugs at the intervals recommended in
Group O, Lubrication and Maintenance.
EXCEPT 4.7L H.O. ENGINE :Spark plugs that
have low mileage may be cleaned and reused if not
otherwise defective, carbon or oil fouled. Also refer to
Spark Plug Conditions.4.7L H.O. ENGINE :Never
clean spark plugs on the 4.7L H.O. engine. Damage
to the platinum rivet will result.
CAUTION: EXCEPT 4.7L H.O. ENGINE : Never use a
motorized wire wheel brush to clean the spark
plugs. Metallic deposits will remain on the spark
plug insulator and will cause plug misfire.
H.O. Gap Adjustment:If equipped with the 4.7L
H.O. engine, do not use a wire-type gapping tool as
damage to the platinum rivet on the center electrode
may occur. Use a tapered-type gauge (Fig. 24).
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS
NORMAL OPERATING
The few deposits present on the spark plug will
probably be light tan or slightly gray in color. This is
evident with most grades of commercial gasoline
Fig. 24 PLUG GAP - 4.7L H.O.
1 - TAPER GAUGE
WJIGNITION CONTROL 8I - 15
KNOCK SENSOR (Continued)

EMIC also uses several hard wired inputs in order to
perform its many functions. The EMIC module incor-
porates a blue-green digital Vacuum Fluorescent Dis-
play (VFD) for displaying odometer and trip
odometer information.
The EMIC houses six analog gauges and has pro-
visions for up to twenty indicators (Fig. 2). The
EMIC includes the following analog gauges:
²Coolant Temperature Gauge
²Fuel Gauge
²Oil Pressure Gauge
²Speedometer
²Tachometer
²Voltage Gauge
Some of the EMIC indicators are automatically
configured when the EMIC is connected to the vehi-
cle electrical system for compatibility with certain
optional equipment or equipment required for regula-
tory purposes in certain markets. While each EMIC
may have provisions for indicators to support every
available option, the configurable indicators will not
be functional in a vehicle that does not have the
equipment that an indicator supports. The EMIC
includes provisions for the following indicators (Fig.
2):
²Airbag Indicator (with Airbags only)
²Antilock Brake System (ABS) Indicator
²Brake Indicator
²Check Gauges Indicator
²Coolant Low Indicator (with Diesel Engine
only)
²Cruise Indicator
²Four-Wheel Drive Part Time Indicator
(with Selec-Trac NVG-242 Transfer Case only)
²Front Fog Lamp Indicator (with Front Fog
Lamps only)
²High Beam Indicator
²Low Fuel Indicator
²Malfunction Indicator Lamp (MIL)
²Overdrive-Off Indicator (except Diesel
Engine)
²Rear Fog Lamp Indicator (with Rear Fog
Lamps only)
²Seatbelt Indicator
²Sentry Key Immobilizer System (SKIS)
Indicator
²Transmission Overtemp Indicator (except
Diesel Engine)²Turn Signal (Right and Left) Indicators
²Wait-To-Start Indicator (with Diesel Engine
only)
²Water-In-Fuel Indicator (with Diesel Engine
only)
Many indicators in the EMIC are illuminated by a
dedicated Light Emitting Diode (LED) that is sol-
dered onto the EMIC electronic circuit board. The
LEDs are not available for service replacement and,
if damaged or faulty, the entire EMIC must be
replaced. Base cluster illumination is accomplished
by dimmable incandescent back lighting, which illu-
minates the gauges for visibility when the exterior
lighting is turned on. Premium cluster illumination
is accomplished by a dimmable electro-luminescent
lamp that is serviced only as a unit with the EMIC.
Each of the incandescent bulbs is secured by an inte-
gral bulb holder to the electronic circuit board from
the back of the cluster housing. The incandescent
bulb/bulb holder units are available for service
replacement.
Hard wired circuitry connects the EMIC to the
electrical system of the vehicle. These hard wired cir-
cuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system
and to the EMIC through the use of a combination of
soldered splices, splice block connectors, and many
different types of wire harness terminal connectors
and insulators. Refer to the appropriate wiring infor-
mation. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
The EMIC modules for this model are serviced only
as complete units. The EMIC module cannot be
adjusted or repaired. If a gauge, an LED indicator,
the VFD, the electronic circuit board, the circuit
board hardware, the cluster overlay, the electro-lumi-
nescent lamp (premium model only) or the EMIC
housing are damaged or faulty, the entire EMIC mod-
ule must be replaced. The cluster lens, hood and
mask unit and the individual incandescent lamp
bulbs with holders are available for service replace-
ment.
WJINSTRUMENT CLUSTER 8J - 3
INSTRUMENT CLUSTER (Continued)

certain conditions or inputs to provide the vehicle
operator with an audible alert to supplement a visual
indication.
The EMIC circuitry operates on battery current
received through fused B(+) fuses in the Power Dis-
tribution Center (PDC) and the Junction Block (JB)
on a non-switched fused B(+) circuit, and on battery
current received through a fused ignition switch out-
put (run-start) fuse in the JB on a fused ignition
switch output (run-start) circuit. This arrangement
allows the EMIC to provide some features regardless
of the ignition switch position, while other features
will operate only with the ignition switch in the On
or Start positions. The EMIC circuitry is grounded
through two separate ground circuits of the instru-
ment panel wire harness. These ground circuits
receive ground through take outs of the instrument
panel wire harness with eyelet terminal connectors
that are secured by a nut to a ground stud located on
the floor panel transmission tunnel beneath the cen-
ter floor console, just forward of the Airbag Control
Module (ACM).
The EMIC also has a self-diagnostic actuator test
capability, which will test each of the PCI bus mes-
sage-controlled functions of the cluster by lighting
the appropriate indicators (except the airbag indica-
tor), sweeping the gauge needles across the gauge
faces from their minimum to their maximum read-
ings, and stepping the odometer display sequentially
from all zeros through all nines. (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). The self-diagnostic actuator test
can be initialized manually or using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the EMIC.
GAUGES
All gauges receive battery current through the
EMIC circuitry when the ignition switch is in the On
or Start positions. With the ignition switch in the Off
position battery current is not supplied to any
gauges, and the EMIC circuitry is programmed to
move all of the gauge needles back to the low end of
their respective scales. Therefore, the gauges do not
accurately indicate any vehicle condition unless the
ignition switch is in the On or Start positions. All of
the EMIC gauges, except the odometer, are air core
magnetic units. Two fixed electromagnetic coils are
located within each gauge. These coils are wrapped
at right angles to each other around a movable per-
manent magnet. The movable magnet is suspended
within the coils on one end of a pivot shaft, while the
gauge needle is attached to the other end of the
shaft. One of the coils has a fixed current flowingthrough it to maintain a constant magnetic field
strength. Current flow through the second coil
changes, which causes changes in its magnetic field
strength. The current flowing through the second coil
is changed by the EMIC circuitry in response to mes-
sages received over the PCI data bus. The gauge nee-
dle moves as the movable permanent magnet aligns
itself to the changing magnetic fields created around
it by the electromagnets.
The gauges are diagnosed using the EMIC self-di-
agnostic actuator test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the PCI data bus, and
the data bus message inputs to the EMIC that con-
trol each gauge requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
Specific operation details for each gauge may be
found elsewhere in this service information.
VACUUM-FLUORESCENT DISPLAY
The Vacuum-Fluorescent Display (VFD) module is
soldered to the EMIC circuit board. The display is
active with the ignition switch in the On or Start
positions, and inactive when the ignition switch is in
any other position. The illumination intensity of the
VFD is controlled by the EMIC circuitry based upon
electronic dimming level messages received from the
BCM over the PCI data bus, and is synchronized
with the illumination intensity of other VFDs in the
vehicle. The BCM provides dimming level messages
based upon internal programming and inputs it
receives from the control knob and control ring on
the control stalk of the left (lighting) multi-function
switch on the steering column.
The VFD has several display capabilities including
odometer and trip odometer information. An odome-
ter/trip odometer switch on the EMIC circuit board is
used to control the display modes. This switch is
actuated manually by depressing the odometer/trip
odometer switch button that extends through the
lower edge of the cluster lens, just right of the speed-
ometer. Actuating this switch momentarily with the
ignition switch in the On position will toggle the
VFD between the odometer and trip odometer modes.
The EMIC microprocessor remembers which display
mode is active when the ignition switch is turned to
the Off position, and returns the display to that
mode when the ignition switch is turned On again.
Depressing the switch button for about two seconds
while the VFD is in the trip odometer mode will
reset the trip odometer value to zero. Holding this
switch depressed while turning the ignition switch
from the Off position to the On position will initiate
the EMIC self-diagnostic actuator test. Refer to the
appropriate diagnostic information for additional
details on this VFD function.
WJINSTRUMENT CLUSTER 8J - 5
INSTRUMENT CLUSTER (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)

an input from the auto headlamp light sensor to
determine the ambient light levels. If the BCM
decides that the exterior lighting is turned on in the
daylight, it overrides the selected panel dimmer
switch signal by sending a message over the PCI
data bus to illuminate all vacuum fluorescent dis-
plays at full brightness for improved visibility in day-
time light levels. The automatic parade mode has no
effect on the incandescent bulb illumination intensity.
The hard wired cluster illumination circuits
between the left (lighting) multi-function switch and
the BCM may be diagnosed using conventional diag-
nostic tools and methods. The electro-luminescent
lamp is diagnosed using the EMIC self-diagnostic
actuator test. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING).
However, proper testing of the EMIC and the elec-
tronic dimming level messages sent by the BCM over
the PCI data bus requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
CHIME SERVICE
The EMIC is programmed to request chime service
from the Body Control Module (BCM) when certain
indicators are illuminated. The EMIC chime request
for illumination of the low fuel indicator is a cus-
tomer programmable feature. When the programmed
conditions are met, the EMIC generates an electronic
chime request message and sends it over the PCI
data bus to the BCM. Upon receiving the proper
chime request, the BCM activates an integral chime
tone generator to provide the audible chime tone to
the vehicle operator. (Refer to 8 - ELECTRICAL/
CHIME WARNING SYSTEM - OPERATION). Proper
testing of the PCI data bus and the electronic chime
request message outputs from the EMIC requires the
use of a DRBIIItscan tool. Refer to the appropriate
diagnostic information.
DIAGNOSIS AND TESTING - INSTRUMENT
CLUSTER
If all of the instrument cluster gauges and/or indi-
cators are inoperative, refer to PRELIMINARY
DIAGNOSIS . If an individual gauge or Programma-
ble Communications Interface (PCI) data bus mes-
sage-controlled indicator is inoperative, refer to
ACTUATOR TEST . If an individual hard wired indi-
cator is inoperative, refer to the diagnosis and testing
information for that specific indicator. If the base
instrument cluster incandescent illumination lighting
is inoperative, refer to CLUSTER ILLUMINATION
DIAGNOSIS . If the premium instrument cluster
electro-luminescent illumination lighting is inopera-
tive, refer to ACTUATOR TEST . Refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connectorrepair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, splices and grounds.
NOTE: Occasionally, a condition may be encoun-
tered where the gauge pointer for the speedometer
or the tachometer becomes caught on the wrong
side of the pointer stop. To correct this condition,
the technician should use a DRBIIITscan tool and
the appropriate diagnostic information to perform
the instrument cluster self-diagnostic actuator test
procedure. When performed, the actuator test pro-
cedure will automatically return the pointer to the
correct side of the pointer stop.
PRELIMINARY DIAGNOSIS
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SIDE CURTAIN AIRBAG,
FRONT IMPACT SENSOR, SIDE IMPACT SENSOR,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: ON VEHICLES EQUIPPED WITH THE
PREMIUM INSTRUMENT CLUSTER, THE CLUSTER
CIRCUITRY PROVIDES AN ALTERNATING CURRENT
TO SUPPLY POWER TO THE ELECTRO-LUMINES-
CENT ILLUMINATION LAMP THROUGH A PIGTAIL
WIRE AND CONNECTOR THAT IS ACCESSIBLE AT
THE BACK OF THE CLUSTER HOUSING. USE
PROPER PRECAUTIONS WHEN HANDLING THIS
UNIT DURING DIAGNOSIS OR SERVICE TO AVOID
ELECTRICAL SHOCK AND POSSIBLE PERSONAL
INJURY.
(1) Check the fused B(+) fuse (Fuse 17 - 10
ampere) in the Junction Block (JB). If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
(Fuse 17 - 10 ampere) in the JB. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit between
WJINSTRUMENT CLUSTER 8J - 7
INSTRUMENT CLUSTER (Continued)

the JB and the Power Distribution Center (PDC) as
required.
(3) Check the fused ignition switch output (run-
start) fuse (Fuse 22 - 10 ampere) in the JB. If OK, go
to Step 4. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run-start) fuse (Fuse 22 - 10 ampere) in the
JB. If OK, go to Step 5. If not OK, repair the open
fused ignition switch output (run-start) circuit
between the JB and the ignition switch as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster. Reconnect the bat-
tery negative cable. Check for battery voltage at the
fused B(+) circuit cavity of the instrument panel wire
harness connector for the instrument cluster. If OK,
go to Step 6. If not OK, repair the open fused B(+)
circuit between the instrument cluster and the JB as
required.
(6) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run-start) circuit cavity of the instrument
panel wire harness connector for the instrument clus-
ter. If OK, go to Step 7. If not OK, repair the open
fused ignition switch output (run-start) circuit
between the instrument cluster and the JB as
required.
(7) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Check for continuity between each of the ground cir-
cuit cavities of the instrument panel wire harness
connector for the instrument cluster and a good
ground. There should be continuity. If OK, refer to
the ACTUATOR TEST . If not OK, repair the open
ground circuit(s) between the instrument cluster and
ground (G200) as required.
ACTUATOR TEST
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SIDE CURTAIN AIRBAG,
FRONT IMPACT SENSOR, SIDE IMPACT SENSOR,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: ON VEHICLES EQUIPPED WITH THE
PREMIUM INSTRUMENT CLUSTER, THE CLUSTER
CIRCUITRY PROVIDES AN ALTERNATING CURRENT
TO SUPPLY POWER TO THE ELECTRO-LUMINES-
CENT ILLUMINATION LAMP THROUGH A PIGTAIL
WIRE AND CONNECTOR THAT IS ACCESSIBLE AT
THE BACK OF THE CLUSTER HOUSING. USE
PROPER PRECAUTIONS WHEN HANDLING THIS
UNIT DURING DIAGNOSIS OR SERVICE TO AVOID
ELECTRICAL SHOCK AND POSSIBLE PERSONAL
INJURY.
The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a self-
diagnostic test that will confirm that the instrument
cluster circuitry, the gauges, the PCI data bus mes-
sage controlled indicators, and the electro-lumines-
cent illumination lamp (if equipped) are capable of
operating as designed. During the actuator test the
instrument cluster circuitry will sweep each of the
gauge needles across the gauge faces, illuminate each
of the segments in the Vacuum-Fluorescent Display
(VFD), turn all of the PCI data bus message-con-
trolled indicators on and off again, and turn the elec-
tro-luminescent illumination lamp (if equipped) on
and off again.
Successful completion of the actuator test will con-
firm that the instrument cluster is operational. How-
ever, there may still be a problem with the PCI data
bus, the Powertrain Control Module, the Airbag Con-
trol Module (ACM), the Body Control Module (BCM),
the Controller Anti-lock Brake (CAB), the Sentry Key
Immobilizer Module (SKIM), or the inputs to one of
these electronic control modules. Use a DRBIIItscan
tool to diagnose these components. Refer to the
appropriate diagnostic information.
If an individual indicator lamp or the electro-lumi-
nescent illumination lamp do not illuminate during
the actuator test, the instrument cluster should be
removed. However, check that the incandescent lamp
bulb is not faulty, that the bulb holder is properly
installed on the instrument cluster electronic circuit
board, or that the electro-luminescent lamp pigtail
wire connector is properly connected to the instru-
ment cluster electronic circuit board before consider-
ing instrument cluster replacement. If the bulb and
bulb holder, or the electro-luminescent lamp connec-
tion check OK, replace the faulty instrument cluster
unit.
(1) Begin the test with the ignition switch in the
Off position.
(2) Depress the odometer/trip odometer switch but-
ton.
8J - 8 INSTRUMENT CLUSTERWJ
INSTRUMENT CLUSTER (Continued)