2002 JEEP LIBERTY instrument panel

HORN
TABLE OF CONTENTS
page page
HORN SYSTEM
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - HORN SYSTEM . . . 1
HORN
DIAGNOSIS AND TESTING - HORN..........2
REMOVAL.............................3
INSTALLATION..........................3HORN RELAY
DIAGNOSIS AND TESTING - HORN RELAY....3
REMOVAL.............................3
INSTALLATION..........................3
HORN SWITCH
DESCRIPTION..........................4
DIAGNOSIS AND TESTING - HORN SWITCH . . . 4
HORN SYSTEM
DESCRIPTION
A dual-note electric horn system is standard facto-
ry-installed equipment on this model (Fig. 1).
The dual-note horn system features dual electro-
magnetic horn units. The horn system includes the
following major components:
²Horn- The two horns are located below the
Power Distribution Center (PDC).
²Horn Relay- The horn relay is located in the
Junction Block (JB).²Horn Switch- The horn switch is molded into
the driver airbag assembly.OPERATION
The horn system operates on battery current
received through fuse 3 in the Junction Block (JB).
The horn system circuit is designed so that the sys-
tem will remain operational, regardless of the igni-
tion switch position.
DIAGNOSIS AND TESTING - HORN SYSTEM
In most cases, any problem involving continually
sounding horns can be quickly alleviated by removing
the horn relay from the Junction Block (JB). Refer to
horn relay for the removal procedure. Refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, further details on wire
harness routing and retention, as well as pin-out and
location views for the various wire harness connec-
tors, splices and grounds.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
Fig. 1 HORN LOCATION
1 - HIGH NOTE HORN
2 - LOW NOTE HORN
KJHORN 8H - 1

HORN SYSTEM DIAGNOSIS TABLE
CONDITION POSSIBLE CAUSES CORRECTION
BOTH HORNS
INOPERATIVE1. Faulty fuse. 1. Check the fuse in the Junction Block (JB).
Replace the fuse and repair the shorted circuit or
component, if required.
2. Faulty horn relay. 2. Refer to horn relay for the proper diagnosis
and testing procedures. Replace the horn relay or
repair the open horn relay circuit, if required.
3. Faulty horn switch. 3. Refer to horn switch for the proper diagnosis
and testing procedure. Replace the horn switch or
repair the open horn switch circuit, if required.
4. Faulty horns. 4. Refer to horn for the proper diagnosis and
testing procedure. Replace the horns or repair the
open horn circuit, if required.
ONE HORN INOPERATIVE 1. Faulty horn. 1. Refer to horn for the proper diagnosis and
testing procedures. Replace the horn or repair the
open horn circuit, if required.
HORN SOUNDS
CONTINUOUSLY1. Faulty horn relay. 1. Refer to horn relay for the proper diagnosis
and testing procedure. Replace the horn relay or
repair the shorted horn relay control circuit, if
required.
2. Faulty horn switch. 2. Refer to horn switch for the proper diagnosis
and testing procedure. Replace the horn switch or
repair the shorted horn switch circuit, if required.
HORN
DIAGNOSIS AND TESTING - HORN
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices and grounds.(1) Disconnect the wire harness connector from the
horn. Measure the resistance between the horn
ground circuit cavity of the wire harness connector
and a good ground. There should be no measurable
resistance. If OK, go to Step 2. If not OK, replace
wiring as necessary.
(2) Check for battery voltage at the horn relay out-
put circuit cavity of the wire harness connector for
the horn. There should be zero volts. If OK, go to
Step 3. If not OK, refer to horn relay and horn relay
circuit for the proper diagnosis and testing proce-
dures.
(3) Depress the horn switch. There should now be
battery voltage at the horn relay output circuit cavity
of the wire harness connector for the horn. If OK, but
the horn does not sound, replace the faulty horn. If
not OK, refer to horn relay and horn relay circuit for
the proper diagnosis and testing procedures.
8H - 2 HORNKJ
HORN SYSTEM (Continued)

REMOVAL
(1)Disconnect and isolate the battery negative cable.
(2) Disconnect the electrical harness connector
from the horns.
(3) Remove the mounting bolt (Fig. 2).
(4) Remove the horns.
INSTALLATION
(1) Install the horns.
(2) Install the mounting bolt. Tighten bolt to 25
N´m (19 lb. ft.).
(3) Connect the electrical harness connector to the
horns
(4) Connect the battery negative cable.
HORN RELAY
DIAGNOSIS AND TESTING - HORN RELAY
(1) Remove horn relay (Refer to 8 - ELECTRICAL/
HORN/HORN RELAY - REMOVAL).
(2) Using ohmmeter, test between relay connector
terminals 85 to 86 for 75   8 ohms resistance. If
resistance not OK, replace relay (Fig. 3).
(3) Test for continuity between ground and termi-
nal 85 of horn relay.
(a) When the horn switch is not depressed, no
continuity should be present.
(b) Continuity to ground when horn switch is
depressed.
(c) If continuity is not correct replace horn
switch or wiring as necessary, refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connec-
tor repair procedures, details of wire harness rout-ing and retention, connector pin-out information
and location views for the various wire harness
connectors, splices and grounds.
(4) Using voltmeter, test voltage at:
(a) Terminals 30 and 86 of the horn relay to
body ground.
(b) If NO voltage check fuse 3 of the Junction
Block (JB).
(c) If incorrect voltage, repair as necessary. Refer
to the appropriate wiring information. The wiring
information 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 connectors, splices and grounds.
(5) Insert a jumper wire between terminal 30 and
87 of the Junction Block (JB).
(a) If horn sounds replace relay.
(b) If the horn does not sound, install horn relay
and test horn (Refer to 8 - ELECTRICAL/HORN/
HORN - DIAGNOSIS AND TESTING).
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the instrument panel end cap.
(3) Locate and pull the horn relay from the Junc-
tion Block (JB).
INSTALLATION
(1) Locate proper connector, and press relay into
position.
(2) Install instrument panel end cap.
(3) Connect battery negative cable.
Fig. 2 HORN MOUNTING
1 - POWER DISTRIBUTION CENTER
2 - LOW NOTE HORN
3 - HIGH NOTE HORN
Fig. 3 Horn Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJHORN 8H - 3
HORN (Continued)

HORN SWITCH
DESCRIPTION
The horn switch is molded into the driver airbag
assembly. The horn switch can not be serviced sepa-
rately. For service procedures, (Refer to 8 - ELEC-
TRICAL/RESTRAINTS/DRIVER AIRBAG -
REMOVAL).
DIAGNOSIS AND TESTING - HORN SWITCH
For complete circuit diagrams, refer to the appro-
priate wiring information. The wiring information
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 connec-
tors, splices and grounds.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the steering column opening cover.
(3) Check for continuity between the metal steer-
ing column jacket and a good ground. There should
be continuity. If OK, go to Step 4. If not OK,(Refer to
19 - STEERING/COLUMN - INSTALLATION) for
proper installation of the steering column.
(4) Remove the driver side airbag module from the
steering wheel (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL). Discon-
nect the horn switch wire harness connectors from
the driver side airbag module (Fig. 4).
(5) Remove the horn relay from the Junction Block
(JB). Check for continuity between the steering col-umn half of the horn switch feed wire harness con-
nector and a good ground. There should be no
continuity. If OK, go to Step 6. If not OK, repair the
shorted horn relay control circuit to the horn relay in
the Junction Block as required.
(6) Check for continuity between the steering col-
umn half of the horn switch feed wire harness con-
nector and the horn relay control circuit cavity for
the horn relay in the Junction Block. There should be
continuity. If OK, go to Step 7. If not OK, repair the
open horn relay control circuit to the horn relay in
the Junction Block as required.
(7) 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 8. If not OK, replace the
faulty horn switch.
(8) 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 (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL).
Fig. 4 Driver Airbag Housing
1 - HOUSING
2 - HORN SWITCH GROUND WIRE
3 - HORN SWITCH FEED WIRE
4 - INFLATOR
5 - TRIM COVER
8H - 4 HORNKJ

TURN SIGNAL INDICATOR
DESCRIPTION.........................34
OPERATION...........................34
WAIT-TO-START INDICATOR
DESCRIPTION.........................35
OPERATION...........................35
WASHER FLUID INDICATOR
DESCRIPTION.........................35OPERATION...........................36
DIAGNOSIS AND TESTING - WASHER FLUID
INDICATOR..........................36
WATER-IN-FUEL INDICATOR
DESCRIPTION.........................37
OPERATION...........................37
INSTRUMENT CLUSTER
DESCRIPTION
The instrument cluster for this model is an Elec-
troMechanical Instrument Cluster (EMIC) module
that is located in the instrument panel above the
steering column opening, directly in front of the
driver (Fig. 1). The remainder of the EMIC, including
the mounts and the electrical connections, are con-
cealed behind the cluster bezel. The EMIC gauges
and indicators are protected by an integral clear
plastic cluster lens, and are visible through a dedi-
cated opening in the cluster bezel on the instrument
panel. Just behind the cluster lens is the cluster hood
and an integral cluster mask, which are constructed
of molded black plastic. Two cluster masks are used;
a base black version is used on base models, while a
premium black version features a chrome trim ring
around the perimeter of each gauge opening is used
on premium models. The cluster hood serves as a
visor and shields the face of the cluster from ambient
light and reflections to reduce glare, while the cluster
mask serves to separate and define the individual
gauges and indicators of the EMIC. On the lower
edge of the cluster lens just right of the speedometer,
the black plastic odometer/trip odometer switch but-
ton protrudes through dedicated holes in the clustermask and the cluster lens. The molded plastic EMIC
lens, hood and mask unit has three integral mount-
ing tabs, one each on the lower outboard corners of
the unit and one on the upper surface of the hood
near the center. These mounting tabs are used to
secure the EMIC to the molded plastic instrument
panel cluster carrier with two screws at the top, and
one screw at each outboard tab. A single molded con-
nector receptacle located on the EMIC electronic cir-
cuit board is accessed from the back of the cluster
housing and is connected to the vehicle electrical sys-
tem through a single dedicated take out and connec-
tor of the instrument panel wire harness.
Behind the cluster lens, hood, and mask unit is the
cluster overlay and gauges. The overlay is a lami-
nated plastic unit. The dark, visible, outer surface of
the overlay is marked with all of the gauge dial faces
and graduations, but this layer is also translucent.
The darkness of this outer layer prevents the cluster
from appearing cluttered or busy by concealing the
cluster indicators that are not illuminated, while the
translucence of this layer allows those indicators and
icons that are illuminated to be readily visible. The
underlying layer of the overlay is opaque and allows
light from the various indicators and illumination
lamps behind it to be visible through the outer layer
of the overlay only through predetermined cutouts.
The orange gauge pointers are each illuminated
internally. The EMIC electronic circuitry is protected
by a molded plastic rear cover that features several
round access holes for service of the cluster illumina-
tion lighting and a single rectangular access hole for
the EMIC connector receptacle. The EMIC housing,
circuit board, gauges, and overlay unit are sand-
wiched between the lens, hood, and mask unit and
the rear cover with screws.
Twelve versions of the EMIC module are offered on
this model, six base and six premium. These versions
accommodate all of the variations of optional equip-
ment and regulatory requirements for the various
markets in which the vehicle will be offered. This
module utilizes integrated circuitry and information
carried on the Programmable Communications Inter-
face (PCI) data bus network for control of all gauges
and many of the indicators. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/COM-
MUNICATION - DESCRIPTION - PCI BUS). The
EMIC also uses several hard wired inputs in order to
Fig. 1 Instrument Cluster
1 - INSTRUMENT PANEL
2 - INSTRUMENT CLUSTER
8J - 2 INSTRUMENT CLUSTERKJ

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, as well as several warning
messages and certain diagnostic information. In addi-
tion to instrumentation and indicators, the EMIC has
the hardware and software needed to provide the fol-
lowing features:
²Chime Warning Service- A chime tone gener-
ator on the EMIC electronic circuit board provides
audible alerts to the vehicle operator and eliminates
the need for a separate chime module. (Refer to 8 -
ELECTRICAL/CHIME WARNING SYSTEM -
DESCRIPTION).
²Panel Lamps Dimming Service- The EMIC
provides a hard wired 12-volt Pulse-Width Modulated
(PWM) output that synchronizes the dimming level
of the radio display, gear selector indicator, heater-air
conditioner control, and all other dimmable lighting
on the panel lamps dimmer circuit with that of the
cluster illumination lamps and VFD.
The EMIC houses four analog gauges and has pro-
visions for up to twenty-four indicators (Fig. 2). The
EMIC includes the following analog gauges:
²Coolant Temperature Gauge
²Fuel Gauge
²Speedometer
²Tachometer
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 Airbag System only)
²Antilock Brake System (ABS) Indicator
(with ABS only)
²Brake Indicator
²Charging Indicator
²Coolant Low Indicator (with Diesel Engine
only)
²Cruise Indicator (with Speed Control Sys-
tem only)
²Four-Wheel Drive Full Time Indicator (with
Selec-Trac Transfer Case only)
²Four-Wheel Drive Low Mode Indicator
²Four-Wheel Drive Part Time Indicator
²Front Fog Lamp Indicator (with Front Fog
Lamps only)
²High Beam Indicator
²Low Fuel Indicator²Low Oil Pressure Indicator
²Malfunction Indicator Lamp (MIL)
²Overdrive-Off Indicator (with Automatic
Transmission only)
²Rear Fog Lamp Indicator (with Rear Fog
Lamps only)
²Seatbelt Indicator
²Security Indicator (with Vehicle Theft
Security System only)
²Sentry Key Immobilizer System (SKIS)
Indicator (with SKIS only)
²Transmission Overtemp Indicator (with
Automatic Transmission only)
²Turn Signal (Right and Left) Indicators
²Wait-To-Start Indicator (with Diesel Engine
only)
²Water-In-Fuel Indicator (with Diesel Engine
only)
Each indicator in the EMIC is 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. Cluster illumination is accomplished by
dimmable incandescent back lighting, which illumi-
nates the gauges for visibility when the exterior
lighting is turned on. Each of the incandescent bulbs
is secured by an integral 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, 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.
KJINSTRUMENT CLUSTER 8J - 3
INSTRUMENT CLUSTER (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
Fig. 2 EMIC Gauges & Indicators
1 - SKIS INDICATOR 16 - REAR FOG LAMP INDICATOR
2 - AIRBAG INDICATOR 17 - ABS INDICATOR
3 - LOW FUEL INDICATOR 18 - CHARGING INDICATOR
4 - WAIT-TO-START INDICATOR 19 - WATER-IN-FUEL INDICATOR
5 - OVERDRIVE-OFF INDICATOR 20 - ENGINE TEMPERATURE GAUGE
6 - COOLANT LOW INDICATOR 21 - ODOMETER/TRIP ODOMETER SWITCH BUTTON
7 - SEATBELT INDICATOR 22 - ODOMETER/TRIP ODOMETER DISPLAY
8 - TACHOMETER 23 - CRUISE INDICATOR
9 - LEFT TURN INDICATOR 24 - LOW OIL PRESSURE INDICATOR
10 - HIGH BEAM INDICATOR 25 - TRANSMISSION OVERTEMP INDICATOR
11 - RIGHT TURN INDICATOR 26 - PART TIME 4WD INDICATOR
12 - SPEEDOMETER 27 - BRAKE INDICATOR
13 - FRONT FOG LAMP INDICATOR 28 - FULL TIME 4WD INDICATOR
14 - 4WD LOW MODE INDICATOR 29 - SECURITY INDICATOR
15 - MALFUNCTION INDICATOR LAMP (MIL) 30 - FUEL GAUGE
8J - 4 INSTRUMENT CLUSTERKJ
INSTRUMENT CLUSTER (Continued)

gauge readings during normal operation that are con-
sistent with customer expectations. However, when
abnormal conditions exist such as high coolant tem-
perature, the algorithm can drive the gauge pointer
to an extreme position and the microprocessor can
sound a chime through the on-board chime tone gen-
erator to provide distinct visual and audible indica-
tions of a problem to the vehicle operator. The
instrument cluster circuitry may also perform chime
service for other electronic modules in the vehicle
based upon electronic chime tone request messages
received over the PCI data bus to provide the vehicle
operator with an audible alert to supplement a visual
indication. One such alert is a door ajar warning
chime, which the EMIC provides by monitoring PCI
bus messages from the Body Control Module (BCM).
The EMIC circuitry operates on battery current
received through a fused B(+) fuse in the Junction
Block (JB) on a non-switched fused B(+) circuit, and
on battery current received through a fused ignition
switch output (run-start) fuse in the JB on a fused
ignition switch output (run-start) circuit. This
arrangement allows the EMIC to provide some fea-
tures regardless of the ignition switch position, while
other features will operate only with the ignition
switch in the On or Start positions. The EMIC
receives a ground input from the BCM as a wake-up
signal in order to provide the ignition-off features.
The EMIC circuitry is grounded through a ground
circuit and take out of the instrument panel wire
harness with an eyelet terminal connector that is
secured by a nut to a ground stud located on the left
instrument panel end bracket.
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 to several calibra-
tion points across the gauge faces, and stepping the
odometer display sequentially from all ones through
all nines. (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). 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 sup-
plied to any gauges, and the EMIC circuitry is pro-
grammed 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 condi-
tion unless the ignition switch is in the On or Start
positions. All of the EMIC gauges, except the odome-
ter, are air core magnetic units. Two fixed electro-magnetic coils are located within each gauge. These
coils are wrapped at right angles to each other
around a movable permanent 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 flowing through 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 messages received over the PCI data bus.
The gauge needle 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 electronic data bus message inputs to the EMIC
that control each gauge require the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation. Specific operation details for each gauge may
be found elsewhere in this service information.
VACUUM-FLUORESCENT DISPLAY The Vacu-
um-Fluorescent Display (VFD) module is soldered to
the EMIC circuit board. The display is active when
the driver door is opened with the ignition switch in
the Off or Accessory positions (Rental Car mode), and
with the ignition switch in the On or Start positions.
The VFD is inactive when the ignition switch is in
the Off or Accessory positions and the driver door is
closed. The illumination intensity of the VFD is con-
trolled by the EMIC circuitry based upon electronic
dimming level messages received from the BCM over
the PCI data bus, and is synchronized with the illu-
mination 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 left (lighting)
control stalk of the multi-function switch on the
steering column.
The VFD has several display capabilities including
odometer, trip odometer, and warning messages
whenever the appropriate conditions exist. The VFD
warning messages include:
²ªdoorº- indicating a door is ajar.
²ªgateº- indicating the tailgate is ajar.
²ªglassº- indicating the tailgate glass is ajar.
²ªlowashº- indicating that the washer fluid
level is low.
²ªno busº- indicating there is no PCI data bus
communication detected.
An odometer/trip odometer switch on the EMIC cir-
cuit board is used to control the display modes. This
switch is actuated manually by depressing the odom-
KJINSTRUMENT CLUSTER 8J - 5
INSTRUMENT CLUSTER (Continued)