Operation - Chrysler Vehicle User Manual

TJ
INSTRUMENT CLUSTER (Continued)
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
INSTRUMENT CLUSTER
electronic messages that are transmitted by other
electronic modules over the Programmable Commuta-
tions Interface (PCI) data bus network. (Refer to 8 -
ELECTRICAL/ELECTRONIC
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-
tinct visual and/or audible indications of a problem to
the vehicle operator. The instrument cluster circuitry
may also produce audible warnings for other elec-
tronic modules in the vehicle based upon electronic
tone request messages received over the PCI data
bus. Each audible warning is intended to provide the
vehicle operator with an audible alert to supplement
a visual indication.
The EMIC circuitry operates on battery current
received through the Ignition-Off Draw (IOD) fuse in
the Power Distribution Center (PDC) on a non-
switched fused B(+) circuit, and on battery current
received through a fuse in the fuse block on a fused
ignition switch output
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 cir-
cuitry is grounded through a ground circuit and take
out of the instrument panel wire harness with an
eyelet terminal connector that is secured under a
ground screw to the back of the instrument panel
structural support near the lower left corner of the
instrument panel, just inboard of 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, positioning the gauge nee-
dles at several predetermined calibration points
across the gauge faces, and illuminating all segments
of the odometer/trip odometer Vacuum-Fluorescent
Display (VFD) unit. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND TEST-
ING). See the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the EMIC.
8J - 5
CONTROL MOD-
(run-start) circuit. This