troMechanical Instrument Cluster (EMIC) 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 concealed within
the instrument panel behind the cluster bezel.
Besides analog gauges and indicators, the EMIC
module incorporates a blue-green digital Vacuum
Fluorescent Display (VFD) unit for displaying odom-
eter/trip odometer information and certain diagnostic
information. The instrument cluster for this model
also includes the hardware and software necessary to
serve as an electronic body control module.

The EMIC gauges and indicators are visible

through a dedicated opening in the cluster bezel on
the instrument panel and are protected by a clear
plastic cluster lens (Fig. 2). Eight integral latch for-
mations around the outer perimeter of the lens
secure the lens unit to the cluster hood and the clus-
ter housing. On the lower edge of the cluster lens
just right of center, a small molded rubber boot cov-
ers the odometer/trip odometer switch button and
seals a dedicated pocketed hole in the lens through
which the switch button protrudes. Just behind the
cluster lens is the cluster hood and an integral clus-
ter mask, which are constructed of molded black
plastic. The cluster hood serves as a visor and shields
the face of the cluster from ambient light and reflec-
tions to reduce glare, while the cluster mask trims
the outside perimeter of the cluster overlay. The clus-
ter hood and mask unit is secured to the cluster

housing with five integral latch formations around its
perimeter.

The rear of the cluster housing and the EMIC elec-

tronic circuitry are protected by a molded plastic rear
cover, which is secured to the cluster housing with
two screws, eight integral latch formations around its
perimeter, and a single latch that is integral to the
cluster housing. The rear cover includes clearance
holes for service access to each of the five general
illumination lighting and the one high beam indica-
tor incandescent bulb and bulb holder units installed
on the cluster circuit board, and for the two color-
coded cluster connector receptacles. The connector
receptacles on the back of the cluster electronic cir-
cuit board connect the EMIC to the vehicle electrical
system through two take outs with color-coded con-
nectors from the instrument panel wire harness.

Sandwiched between the rear cover and the lens,

hood and mask unit is the cluster housing. The
molded plastic cluster housing serves as the carrier
for the cluster circuit board and circuitry, the cluster
connector receptacles, the gauges, a Light Emitting
Diode (LED) for each cluster indicator, the VFD unit,
an audible tone generator, the cluster overlay, the
gauge pointers, the odometer/trip odometer switch
and the switch button. The molded plastic EMIC
housing has four integral mounting tabs, two on the
lower outboard edges of the housing and one on each
side. A screw through each of these four mounting
tabs secures the EMIC to the instrument panel struc-
tural support.

The cluster overlay is a laminated plastic unit. The

dark, visible, outer surface of the overlay is marked
with all of the gauge dial faces and graduations, but

Fig. 1 Instrument Cluster

1 - CLUSTER BEZEL
2 - INSTRUMENT CLUSTER

Fig. 2 Instrument Cluster Components

1 - REAR COVER
2 - CLUSTER HOUSING
3 - CLUSTER HOOD & MASK
4 - CLUSTER LENS
5 - SWITCH BUTTON BOOT

8J - 2

INSTRUMENT CLUSTER

this layer is also translucent. The darkness of this
outer layer prevents the cluster from appearing clut-
tered 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 LED or incandescent lamp for each of the various
indicators and the incandescent illumination lamps
behind it to be visible through the outer layer of the
overlay only through predetermined stencil-like cut-
outs. A rectangular opening near the base of the
overlay between the speedometer and tachometer
dial faces has a smoked clear lens through which the
illuminated VFD unit can be viewed.

Several versions of the EMIC module are offered

on this model. These versions accommodate all of the
variations of optional equipment and regulatory
requirements for the various markets in which the
vehicle will be offered. The microprocessor-based
EMIC utilizes integrated circuitry and information
carried on the Programmable Communications Inter-
face (PCI) data bus network along with several hard
wired analog and multiplexed inputs to monitor sen-
sors and switches throughout the vehicle. In response
to those inputs, the internal circuitry and program-
ming of the EMIC allow it to control and integrate
many electronic functions and features of the vehicle
through both hard wired outputs and the transmis-
sion of electronic message outputs to other electronic
modules in the vehicle over the PCI data bus. (Refer
to

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/COMMUNICATION - DESCRIPTION -
PCI BUS).

Besides typical instrument cluster gauge and indi-

cator support, the electronic functions and features
that the EMIC supports or controls include the fol-
lowing:

• Audible Warnings - The EMIC electronic cir-

cuit board is equipped with an audible tone generator
and programming that allows it to provide various
audible chime tone alerts to the vehicle operator.
(Refer

ELECTRICAL/CHIME/BUZZER

DESCRIPTION).

• Audio System Cabin Equalization - The

EMIC stores the cabin equalization curves for vari-
ous optional speaker system architectures for use by
the radio. The EMIC provides this information when
requested by the radio over the PCI data bus. Chang-
ing the cabin equalization settings of the EMIC
requires the use of a DRBIII

t scan tool. Refer to the

appropriate diagnostic information.

• Axle Locker Control - The EMIC provides the

logic that controls the operation of the rear and front
axle locker feature found on models equipped with
the optional off-road package.

• Electronic Pinion Factor - The EMIC stores

the tire size, axle ratio, and transfer case type infor-
mation for use in calibrating the proper vehicle speed
and distance values for display by the speedometer
and odometer, as well as for use by other electronic
modules in the vehicle. The EMIC provides this
information when requested by other modules over
the PCI data bus. Changing the electronic pinion fac-
tor settings of the EMIC requires the use of a
DRBIII

t scan tool. Refer to the appropriate diagnos-

tic information.

• Interior Lamp Load Shedding - The EMIC

provides a battery saver feature which will automat-
ically turn off all interior lamps that remain on after
a timed interval of about twenty minutes.

• Interior Lighting Control - The EMIC moni-

tors inputs from the interior lighting switch and the
door ajar switches to provide courtesy lamp control.
This includes support for a timed illuminated entry
with a theater-style fade-to-off feature.

• Panel Lamps Dimming Control - The EMIC

provides a hard wired 12-volt Pulse-Width Modulated
(PWM) output that synchronizes the dimming level
of all panel lamps dimmer controlled lamps with that
of the cluster illumination lamps. This includes pro-
viding features such as VFD unit illumination when
a door is ajar (rental car mode), radio illumination
control, a parade mode, and one step dimmable front
and rear lock, cruise, and four-wheel drive indicators.

• Rear Window Defogger Control - The EMIC

provides control and timer functions for the output to
the rear window defogger on vehicles so equipped,
which eliminates the need for a separate control and
timer module for the rear window defogger system.
(Refer to 8 - ELECTRICAL/WINDOW DEFOGGER -
DESCRIPTION).

• Vacuum Fluorescent Display Synchroniza-

tion - The EMIC transmits electronic panel lamp
dimming level messages which allows all other elec-
tronic modules with Vacuum Fluorescent Display
(VFD) units on the PCI data bus to coordinate their
illumination intensity with that of the EMIC VFD
unit.

The EMIC houses six analog gauges and has pro-

visions for up to seventeen indicators (Fig. 3). The
EMIC includes the following analog gauges:

• Coolant Temperature Gauge

• Fuel Gauge

• Oil Pressure Gauge

• Speedometer

• Tachometer

• Voltage 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-

INSTRUMENT CLUSTER

8J - 3

INSTRUMENT CLUSTER (Continued)

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.
3):

• Airbag Indicator (with Airbag System only)

• Antilock Brake System (ABS) Indicator

(with ABS brakes only)

• Brake Indicator

• Check Gauges Indicator

• Cruise Indicator (with Speed Control only)

• Fog Lamp Indicator (with Front or Rear

Fog Lamps only)

• Four-Wheel Drive (4WD) Indicator

• Front Lock Indicator (with Off-Road Pack-

age only)

• High Beam Indicator

• Low Fuel Indicator

• Malfunction Indicator Lamp (MIL)

• Rear Lock Indicator (with Off-Road Pack-

age only)

• Seatbelt Indicator

• Sentry Key Immobilizer System (SKIS)

Indicator (with SKIS only)

• Turn Signal (Right and Left) Indicators
The EMIC high beam indicator is illuminated by a

dedicated incandescent bulb. Each remaining indica-
tor in the EMIC is illuminated by a dedicated LED
that is soldered onto the EMIC electronic circuit
board. The LED units 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 light-
ing, which illuminates the gauges for visibility when
the exterior lighting is turned on. Each of the incan-
descent bulbs is secured by an integral bulb holder to
the electronic circuit board from the back of the clus-
ter housing.

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, a
VFD unit, 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, the cluster
hood and mask unit, the cluster housing rear cover,
the odometer/trip odometer switch button boot, and
the incandescent lamp bulbs with holders are avail-
able for individual service replacement.

OPERATION

The ElectroMechanical Instrument Cluster (EMIC)

in this model also includes the hardware and soft-
ware necessary to serve as the electronic body control
module. The following information deals primarily
with the instrument cluster functions of this unit.
Additional details of the electronic body control func-
tions of this unit may be found within the service
information for the system or component that the
EMIC controls. For example: Additional details of the
audible warning functions of the EMIC are found
within the Chime/Buzzer service information.

The EMIC is designed to allow the vehicle operator

to monitor the conditions of many of the vehicle com-
ponents and operating systems. The gauges and indi-
cators in the EMIC provide valuable information
about the various standard and optional powertrains,
fuel and emissions 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 allow-
ing relative ease of access for service. The micropro-
cessor-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 messages that are transmitted by other
electronic modules over the Programmable Commuta-
tions 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/high battery
voltage, low oil pressure, or high coolant tempera-
ture, the algorithm can drive the gauge pointer to an
extreme position and the microprocessor can turn on
the Check Gauges indicator and/or sound a chime
through the on-board tone generator to provide dis-

8J - 4

INSTRUMENT CLUSTER

INSTRUMENT CLUSTER (Continued)

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