• Brake Indicator
• Check Gauges Indicator
• Cruise Indicator (Odometer VFD)
• Front Fog Lamps Indicator
• High Beam Indicator
• Low Coolant Indicator (Diesel Only)
• Low Fuel Indicator
• Malfunction Indicator Lamp (MIL)
• Overdrive-Off Indicator
• Part-Time Indicator (Selec-Trac Four-Wheel
Drive Only)
• Rear Fog Lamps Indicator
• Seatbelt Indicator
• Sentry Key Immobilizer System (SKIS)
Indicator
• Transmission Overtemp Indicator
• Turn Signal (Right and Left) Indicators
• Wait-To-Start Indicator (Diesel Only)
• Water-In-Fuel Indicator (Diesel Only)
Cluster illumination is accomplished by adjustable
incandescent back lighting, which illuminates the
gauges for visibility when the exterior lighting is
turned on. Each of the EMIC indicator lamps is also
illuminated by a dedicated incandescent bulb. Each
of the incandescent bulbs is secured by an integral
bulb holder to the circuit board from the back of the
cluster 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.
Several component parts of the EMIC for this
model are available for service. The cluster lens, the
cluster hood and mask unit, the major gauges, the
two minor gauge sets, the trip odometer reset knob,
the cluster housing which includes the electronic cir-
cuit board and rear housing cover, and the incandes-
cent lamp bulbs and bulb holders are available for
individual service replacement.
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 indicator lamps
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 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 drives 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 chime tone
requests over the PCI data bus to the Body Control
Module (BCM) when it monitors certain conditions or
inputs to provide the vehicle operator with an audi-
ble alert.
The EMIC circuitry operates on battery current
received through a fuse in the Power Distribution
Center (PDC) and a fuse in the Junction Block (JB)
on a non-switched fused B(+) circuit, and also on bat-
tery current received through a fuse in the JB on a
fused ignition switch output (start-run) 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 Start or On positions. The EMIC cir-
cuitry is grounded through two separate ground cir-
cuits of the instrument panel wire harness. These
ground circuits receive ground through with an eye-
let terminal connector of the instrument panel wire
harness that is secured by a nut to a ground stud
located on the floor panel transmission tunnel
beneath the center 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 indicator lamps (except for the air-
WG
INSTRUMENT CLUSTER
8Js - 3
INSTRUMENT CLUSTER (Continued)
2001 JEEP GRAND CHEROKEE