Operation - Jeep Wrangler 2001 Service Manual

TJ
INSTRUMENT CLUSTER (Continued)
The EMIC module incorporates a blue-green elec-
tronic digital VFD for displaying odometer, trip
odometer, and diagnostic information. The EMIC
includes the following analog gauges:
• Coolant Temperature Gauge
• Fuel Gauge
• Oil Pressure Gauge
• Speedometer
• Tachometer
• Voltage Gauge
The EMIC also includes provisions for the follow-
ing indicators:
• Airbag Indicator
• Antilock Brake System (ABS) Indicator
• Brake Indicator
• Check Gauges Indicator
• Cruise Indicator
• Fog Lamp (Front or Rear) Indicator
• Four-Wheel Drive (Part Time and/or Full
Time) Indicator
• High Beam Indicator
• Low Fuel Indicator
• Malfunction Indicator Lamp (MIL)
• Seatbelt Indicator
• Sentry Key Immobilizer System (SKIS)
Indicator
• Turn Signal (Right and Left) Indicators
• Upshift Indicator (Manual Transmission)
Some of these indicators are automatically config-
ured when the EMIC is connected to the vehicle elec-
trical system. This feature allows those indicators to
be activated or deactivated for compatibility with cer-
tain optional equipment. The EMIC uses electronic
messages received over the PCI data bus from the
Airbag Control Module (ACM), the Sentry Key Immo-
bilizer Module (SKIM), and the Powertrain Control
Module (PCM) to learn whether the vehicle is
equipped with airbags, the Sentry Key Immobilizer
System (SKIS), or cruise control; then, configures the
appropriate indicators accordingly. Once the EMIC
learns that a vehicle has these equipment options
installed, these indicators will function accordingly
for the remainder of the cluster life.
Cluster illumination is accomplished by adjustable
incandescent back lighting, which illuminates the
gauges for visibility when the exterior lighting is
turned on. The EMIC high beam indicator is illumi-
nated by a dedicated incandescent bulb. The remain-
ing indicators in the EMIC are each illuminated by a
dedicated Light Emitting Diode (LED) that is sol-
dered onto the electronic circuit board. Each of the
incandescent bulbs is secured by an integral bulb
holder to the electronic 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-
2001 JEEP WRANGLER
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, the cluster
hood and mask unit, the rear cluster housing cover,
the odometer/trip odometer switch knob boot, and the
incandescent lamp bulbs with 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 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 Commutations Interface
(PCI) data bus network. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/COMMUNI-
CATION - 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 drives the gauge pointer to an
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