Power control DODGE RAM 1500 1998 2.G Repair Manual

(4) Remove coil mounting nut from mounting stud
(Fig. 17).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
5.7L V-8
Before removing or disconnecting any spark plug
cables, note their original position. Remove cables
one-at-a-time. To prevent ignition crossfire, spark
plug cablesMUSTbe placed in cable tray (routing
loom) into their original position.
An individual ignition coil (Fig. 18) is used at each
cylinder. The coil mounts to the top of the valve cover
with 2 bolts (Fig. 19). The bottom of the coil is
equipped with a rubber boot to seal the spark plug to
the coil. Inside each rubber boot is a spring. The
spring is used for a mechanical contact between the
coil and the top of the spark plug.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Unlock electrical connector (Fig. 19) by moving
slide lock first. Press on release lock (Fig. 19) while
pulling electrical connector from coil.
(3) Disconnect secondary high-voltage cable from
coil with a twisting action.
(4) Clean area at base of coil with compressed air
before removal.
(5) Remove 2 mounting bolts (note that mounting
bolts are retained to coil).
(6) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(7) Remove coil from vehicle.
(8) Before installing spark plug cables to either the
spark plugs or coils, or before installing a coil to a
spark plug, apply dielectric grease to inside of boots.
INSTALLATION
3.7L V-6
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Do this while guiding coil
base over mounting stud.
(4) Install coil mounting stud nut. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) If necessary, install throttle body air tube.
4.7L V-8
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Do this while guiding coil
base over mounting stud.
(4) Install coil mounting stud nut. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) If necessary, install throttle body air tube.
5.7L V-8
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Before installing spark plug cables to either the
spark plugs or coils, or before installing a coil to a
spark plug, apply dielectric grease to inside of boots.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Twist coil into position.
(4) Install 2 coil mounting bolts. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) Install cable to coil. To prevent ignition cross-
fire, spark plug cablesMUSTbe placed in cable tray
(routing loom) into their original position. Refer to
Spark Plug Cable Removal for a graphic.
(7) If necessary, install throttle body air tube.
KNOCK SENSOR
DESCRIPTION
The sensors are used only with 3.7L V-6, 4.7L V-8
and 5.7L V-8 engines. On 3.7L V-6 and 4.7L V-8
engines, the 2 knock sensors are bolted into the cyl-
inder block under the intake manifold.
On 5.7L V-8 engines, 2 knock sensors are also
used. These are bolted into each side of the cylinder
block (outside) under the exhaust manifold.
OPERATION
3.7L V-6 / 4.7L V-8 / 5.7L V-8 Engines Only
Two knock sensors are used; one for each cylinder
bank. When the knock sensor detects a knock in one
of the cylinders on the corresponding bank, it sends
an input signal to the Powertrain Control Module
(PCM). In response, the PCM retards ignition timing
for all cylinders by a scheduled amount.
8I - 14 IGNITION CONTROLDR
IGNITION COIL (Continued)

Knock sensors contain a piezoelectric material
which constantly vibrates and sends an input voltage
(signal) to the PCM while the engine operates. As the
intensity of the crystal's vibration increases, the
knock sensor output voltage also increases.
The voltage signal produced by the knock sensor
increases with the amplitude of vibration. The PCM
receives the knock sensor voltage signal as an input.
If the signal rises above a predetermined level, the
PCM will store that value in memory and retard
ignition timing to reduce engine knock. If the knock
sensor voltage exceeds a preset value, the PCM
retards ignition timing for all cylinders. It is not a
selective cylinder retard.
The PCM ignores knock sensor input during engine
idle conditions. Once the engine speed exceeds a
specified value, knock retard is allowed.
Knock retard uses its own short term and long
term memory program.
Long term memory stores previous detonation
information in its battery-backed RAM. The maxi-
mum authority that long term memory has over tim-
ing retard can be calibrated.
Short term memory is allowed to retard timing up
to a preset amount under all operating conditions (as
long as rpm is above the minimum rpm) except at
Wide Open Throttle (WOT). The PCM, using short
term memory, can respond quickly to retard timing
when engine knock is detected. Short term memory
is lost any time the ignition key is turned off.
NOTE: Over or under tightening the sensor mount-
ing bolts will affect knock sensor performance, pos-
sibly causing improper spark control. Always use
the specified torque when installing the knock sen-
sors.
REMOVAL
3.7L V-6 / 4.7L V-8
The 2 knock sensors are bolted into the cylinder
block under the intake manifold (Fig. 20). or (Fig.
21).
NOTE: The left sensor is identified by an identifica-
tion tag (LEFT). It is also identified by a larger bolt
head. The Powertrain Control Module (PCM) must
have and know the correct sensor left/right posi-
tions. Do not mix the sensor locations.
(1) Disconnect knock sensor dual pigtail harness
from engine wiring harness. This connection is made
near rear of engine.
(2) Remove intake manifold. Refer to Engine sec-
tion.(3) Remove sensor mounting bolts (Fig. 20), or
(Fig. 21). Note foam strip on bolt threads. This foam
is used only to retain the bolts to sensors for plant
assembly. It is not used as a sealant. Do not apply
any adhesive, sealant or thread locking compound to
these bolts.
(4) Remove sensors from engine.
5.7L V8
Two sensors are used. Each sensor is bolted into
the outside of cylinder block below the exhaust man-
ifold (Fig. 22).
(1) Raise vehicle.
(2) Disconnect knock sensor electrical connector.
(3) Remove sensor mounting bolt (Fig. 22). Note
foam strip on bolt threads. This foam is used only to
retain the bolts to sensors for plant assembly. It is
not used as a sealant. Do not apply any adhesive,
sealant or thread locking compound to these bolts.
(4) Remove sensor from engine.
INSTALLATION
3.7L V-6 / 4.7L V-8
NOTE: The left sensor is identified by an identifica-
tion tag (LEFT). It is also identified by a larger bolt
head. The Powertrain Control Module (PCM) must
have and know the correct sensor left/right posi-
tions. Do not mix the sensor locations.
Fig. 20 KNOCK SENSOR Ð 3.7L V-6
1 - KNOCK SENSORS (2)
2 - MOUNTING BOLTS
DRIGNITION CONTROL 8I - 15
KNOCK SENSOR (Continued)

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 RKE interface connector,
the gauges, a Light Emitting Diode (LED) for each
cluster indicator, two VFD units, an audible tone
generator, the cluster overlay, the gauge pointers, the
odometer/trip odometer switch and the switch button.
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
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 for each of the various indicators and the
incandescent illumination lamps behind it to be visi-
ble through the outer layer of the overlay only
through predetermined stencil-like cutouts. A rectan-
gular opening in the overlay at the base of both the
speedometer and tachometer dial faces has a smoked
clear lens through which the illuminated VFD units
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 8 - 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:
²Audible Warnings- The EMIC electronic cir-
cuit board is equipped with an audible tone generator
and programming that allows it to provide various
audible alerts to the vehicle operator, including
chime tones and beep tones. An electromechanical
relay is also soldered onto the circuit board to pro-duce audible clicks that emulate the sound of a con-
ventional turn signal or hazard warning flasher.
(Refer to 8 - ELECTRICAL/CHIME/BUZZER -
DESCRIPTION).
²Brake Lamp Control- The EMIC provides
electronic brake lamp request messages to the Front
Control Module (FCM) located on the Integrated
Power Module (IPM) for brake lamp control, exclud-
ing control of the Center High Mounted Stop Lamp
(CHMSL), which remains controlled by a direct hard
wired output of the brake lamp switch.
²Brake Transmission Shift Interlock Control
- The EMIC monitors inputs from the brake lamp
switch, ignition switch, and the Transmission Range
Sensor (TRS), then controls a high-side driver output
to operate the Brake Transmission Shift Interlock
(BTSI) solenoid that locks and unlocks the automatic
transmission gearshift selector lever on the steering
column.
²Cargo Lamp Control- The EMIC provides
direct control of cargo lamp operation with a load
shedding (battery saver) feature which will automat-
ically turn off the cargo lamp if it remains on after a
timed interval.
²Central Locking- The EMIC provides support
for the central locking feature of the power lock sys-
tem. This feature will lock or unlock all doors based
upon the input from the door cylinder lock switch.
Door cylinder lock switches are used only on models
equipped with the optional Vehicle Theft Security
System (VTSS).
²Door Lock Inhibit- The EMIC inhibits locking
of the doors with the power lock switch when the key
is in the ignition switch and the driver side front
door is ajar. However, operation of the door locks is
not inhibited under the same conditions when the
Lock button of the optional RKE transmitter is
depressed.
²Enhanced Accident Response- The EMIC
monitors an input from the Airbag Control Module
(ACM) and, following an airbag deployment, will
immediately disable the power lock output, unlock all
doors by activating the power unlock output, then
enables the power lock output. This feature, like all
other enhanced accident response features, is depen-
dent upon a functional vehicle electrical system fol-
lowing the vehicle impact event.
²Exterior Lighting Control- The EMIC pro-
vides electronic head lamp and/or park lamp request
messages to the Front Control Module (FCM) located
on the Integrated Power Module (IPM) for the appro-
priate exterior lamp control of standard head and
park lamps, as well as optional front fog lamps. This
includes support for headlamp beam selection and
the optical horn feature, also known as flash-to-pass.
DRINSTRUMENT CLUSTER 8J - 3
INSTRUMENT CLUSTER (Continued)

²Exterior Lighting Fail-safe- In the absence of
a headlamp switch input, the EMIC will turn on the
cluster illumination lamps and provide electronic
headlamp low beam and park lamp request messages
to the Front Control Module (FCM) located on the
Integrated Power Module (IPM) for default exterior
lamp operation. The FCM will also provide default
park lamp and headlamp low beam operation and the
EMIC will turn on the cluster illumination lamps if
there is a failure of the electronic data bus commu-
nication between the EMIC and the FCM.
²Heated Seat Control- The EMIC monitors
inputs from the ignition switch and electronic engine
speed messages from the Powertrain Control Module
(PCM) to control a high side driver output to the
heated seat switch Light Emitting Diode (LED) indi-
cators. This input allows the heated seat switches to
wake up the heated seat module if the switch is actu-
ated. The EMIC will de-energize the heated seat
switch LED indicators, which deactivates the heated
seat system, if the ignition switch is turned to any
position except On or Start, or if the engine speed
message indicates zero. (Refer to 8 - ELECTRICAL/
HEATED SEATS - DESCRIPTION).
²Interior 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 fifteen minutes.
²Interior Lamps - Enhanced Accident
Response- The EMIC monitors inputs from the Air-
bag Control Module (ACM) and the Powertrain Con-
trol Module (PCM) to automatically turn on the
interior lighting after an airbag deployment event
ten seconds after the vehicle speed is zero. The inte-
rior lighting remains illuminated until the key is
removed from the ignition switch lock cylinder, at
which time the interior lighting returns to normal
operation and control. This feature, like all other
enhanced accident response features, is dependent
upon a functional vehicle electrical system following
the vehicle impact event.
²Interior Lighting Control- The EMIC moni-
tors inputs from the interior lighting switch, the door
ajar switches, the cargo lamp switch, the reading
lamp switches, and the Remote Keyless Entry (RKE)
module to provide courtesy lamp control. This
includes support for timed illuminated entry with
theater-style fade-to-off and courtesy illumination
defeat features.
²Lamp Out Indicator Control- The EMIC
monitors electronic lamp outage messages from the
Front Control Module (FCM) located on the Inte-
grated Power Module (IPM) in order to provide lamp
out indicator control for the headlamps (low and high
beams), turn signal lamps, and the brake lamps
(excluding CHMSL).²Panel Lamps Dimming Control- The EMIC
provides a hard wired 12-volt Pulse-Width Modulated
(PWM) output that synchronizes the dimming level
of all hard wired panel lamps dimmer controlled
lamps with that of the cluster illumination lamps.
²Parade Mode- The EMIC provides a parade
mode (also known as funeral mode) that allows all
Vacuum-Fluorescent Display (VFD) units in the vehi-
cle to be illuminated at full (daytime) intensity while
driving during daylight hours with the exterior
lamps turned on.
²Power Locks- The EMIC monitors inputs from
the power lock switches and the Remote Keyless
Entry (RKE) receiver module (optional) to provide
control of the power lock motors through high side
driver outputs to the power lock motors. This
includes support for rolling door locks (also known as
automatic door locks), automatic door unlock, a door
lock inhibit mode, and central locking (with the
optional Vehicle Theft Security System only). (Refer
to 8 - ELECTRICAL/POWER LOCKS - DESCRIP-
TION).
²Remote Keyless Entry- The EMIC supports
the optional Remote Keyless Entry (RKE) system fea-
tures, including support for the RKE Lock, Unlock
(with optional driver-door-only unlock, and unlock-
all-doors), Panic, audible chirp, optical chirp, illumi-
nated entry modes, an RKE programming mode, as
well as optional Vehicle Theft Security System
(VTSS) arming (when the proper VTSS arming con-
ditions are met) and disarming.
²Remote Radio Switch Interface- The EMIC
monitors inputs from the optional remote radio
switches and then provides the appropriate electronic
data bus messages to the radio to select the radio
operating mode, volume control, preset station scan
and station seek features.
²Rolling Door Locks- The EMIC provides sup-
port for the power lock system rolling door locks fea-
ture (also known as automatic door locks). This
feature will automatically lock all unlocked doors
each time the vehicle speed reaches twenty-four kilo-
meters-per-hour (fifteen miles-per-hour). Following
an automatic lock event, if the driver side front door
is opened first after the ignition is turned to the Off
position, all doors will be automatically unlocked.
²Turn Signal & Hazard Warning Lamp Con-
trol- The EMIC provides electronic turn and hazard
lamp request messages to the Front Control Module
(FCM) located on the Integrated Power Module (IPM)
for turn and hazard lamp control. The EMIC also
provides an audible click at one of two rates to emu-
late normal and bulb out turn or hazard flasher oper-
ation based upon electronic lamp outage messages
from the FCM, and provides an audible turn signal
on chime warning if a turn is signalled continuously
8J - 4 INSTRUMENT CLUSTERDR
INSTRUMENT CLUSTER (Continued)

for more than about 1.6 kilometers (one mile) and
the vehicle speed remains greater than about twenty-
four kilometers-per-hour (fifteen miles-per-hour).
²Vacuum Fluorescent Display Synchroniza-
tion- The EMIC transmits electronic panel lamp
dimming level messages which allows all other elec-
tronic modules on the PCI data bus with Vacuum
Fluorescent Display (VFD) units to coordinate their
illumination intensity with that of the EMIC VFD
units.
²Vehicle Theft Security System- The EMIC
monitors inputs from the door cylinder lock
switch(es), the door ajar switches, the ignition
switch, and the Remote Keyless Entry (RKE) receiver
module, then provides electronic horn and lighting
request messages to the Front Control Module (FCM)
located on the Integrated Power Module (IPM) for
the appropriate VTSS alarm output features.
²Wiper/Washer System Control- The EMIC
provides electronic wiper and/or washer request mes-
sages to the Front Control Module (FCM) located on
the Integrated Power Module (IPM) for the appropri-
ate wiper and washer system features. (Refer to 8 -
ELECTRICAL/WIPERS/WASHERS - DESCRIP-
TION).
The EMIC houses six analog gauges and has pro-
visions for up to twenty-three indicators (Fig. 3) or
(Fig. 4). The EMIC includes the following analog
gauges:
²Coolant Temperature Gauge
²Fuel Gauge
²Oil Pressure Gauge
²Speedometer
²Tachometer
²Voltage 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-
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) or (Fig. 4):
²Airbag Indicator (with Airbag System only)
²Antilock Brake System (ABS) Indicator
(with ABS or Rear Wheel Anti-Lock [RWAL]
brakes only)
²Brake Indicator
²Cargo Lamp Indicator
²Check Gauges Indicator
²Cruise Indicator (with Speed Control only)
²Door Ajar Indicator²Electronic Throttle Control (ETC) Indicator
(with 5.7L Gasoline Engine only)
²Gear Selector Indicator (with Automatic
Transmission only)
²High Beam Indicator
²Lamp Out Indicator
²Low Fuel Indicator
²Malfunction Indicator Lamp (MIL)
²Seatbelt Indicator
²Security Indicator (with Sentry Key Immo-
bilizer & Vehicle Theft Security Systems only)
²Service Four-Wheel Drive Indicator (with
Four-Wheel Drive only)
²Tow/Haul Indicator (with Automatic Trans-
mission only)
²Transmission Overtemp Indicator (with
Automatic Transmission only)
²Turn Signal (Right and Left) Indicators
²Upshift Indicator (with Manual Transmis-
sion only)
²Washer Fluid Indicator
²Wait-To-Start Indicator (with Diesel Engine
only)
²Water-In-Fuel Indicator (with Diesel Engine
only)
Each indicator in the EMIC, except those located
within one of the VFD units, is illuminated by a ded-
icated 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
lighting, which illuminates 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.
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
DRINSTRUMENT CLUSTER 8J - 5
INSTRUMENT CLUSTER (Continued)

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 individual ser-
vice 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 and is sometimes referred to as the Cab
Compartment Node or CCN. The following informa-
tion deals primarily with the instrument cluster
functions of this unit. Additional details of the elec-
tronic body control functions 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 ofthe 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 Communi-
cations Interface (PCI) data bus network. (Refer to 8
Fig. 3 Gauges & Indicators - Gasoline Engine
1 - MALFUNCTION INDICATOR LAMP 13 - ELECTRONIC THROTTLE CONTROL (ETC) INDICATOR
2 - VOLTAGE GAUGE 14 - ENGINE TEMPERATURE GAUGE
3 - LEFT TURN INDICATOR 15 - SECURITY INDICATOR
4 - TACHOMETER 16 - GEAR SELECTOR INDICATOR DISPLAY (INCLUDES
CRUISE & UPSHIFT INDICATORS)
5 - AIRBAG INDICATOR 17 - CHECK GAUGES INDICATOR
6 - HIGH BEAM INDICATOR 18 - BRAKE INDICATOR
7 - SEATBELT INDICATOR 19 - ABS INDICATOR
8 - SPEEDOMETER 20 - ODOMETER/TRIP ODOMETER DISPLAY (INCLUDES
ENGINE HOURS, WASHER FLUID, LAMP OUTAGE, TOW/HAUL
& SERVICE 4x4 INDICATORS)
9 - RIGHT TURN INDICATOR 21 - ODOMETER/TRIP ODOMETER SWITCH BUTTON
10 - OIL PRESSURE GAUGE 22 - FUEL GAUGE
11 - CARGO LAMP INDICATOR 23 - LOW FUEL INDICATOR
12 - DOOR AJAR INDICATOR 24 - TRANSMISSION OVERTEMP INDICATOR
8J - 6 INSTRUMENT CLUSTERDR
INSTRUMENT CLUSTER (Continued)

- 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 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 audible tone
generator to provide distinct visual and audible indi-
cations of a problem to the vehicle operator. The
instrument cluster circuitry may also produce audi-
ble warnings for other electronic modules in the vehi-
cle based upon electronic tone request messages
received over the PCI data bus. Each audible warn-ing 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 a fused B(+) fuse in the Integrated
Power Module (IPM) on a non-switched fused B(+)
circuit, and on battery current received through a
fused ignition switch output (run-start) fuse in the
IPM on a fused ignition switch output (run-start) cir-
cuit. This arrangement allows the EMIC to provide
some features regardless of the ignition switch posi-
tion, while other features will operate only with the
ignition switch in the On or Start positions. 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 ground screw to a ground location near the center
of the instrument panel structural support.
The EMIC also has a self-diagnostic actuator test
capability, which will test each of the PCI bus mes-
Fig. 4 Gauges & Indicators - Diesel Engine
1 - MALFUNCTION INDICATOR LAMP 14 - ENGINE TEMPERATURE GAUGE
2 - VOLTAGE GAUGE 15 - SECURITY INDICATOR
3 - LEFT TURN INDICATOR 16 - GEAR SELECTOR INDICATOR DISPLAY (INCLUDES
CRUISE & UPSHIFT INDICATORS)
4 - TACHOMETER 17 - WATER-IN-FUEL INDICATOR
5 - AIRBAG INDICATOR 18 - BRAKE INDICATOR
6 - HIGH BEAM INDICATOR 19 - WAIT-TO-START INDICATOR
7 - SEATBELT INDICATOR 20 - ODOMETER/TRIP ODOMETER DISPLAY (INCLUDES
ENGINE HOURS, WASHER FLUID, LAMP OUTAGE, TOW/HAUL
& SERVICE 4x4 INDICATORS)
8 - SPEEDOMETER 21 - ODOMETER/TRIP ODOMETER SWITCH BUTTON
9 - RIGHT TURN INDICATOR 22 - FUEL GAUGE
10 - OIL PRESSURE GAUGE 23 - LOW FUEL INDICATOR
11 - CARGO LAMP INDICATOR 24 - TRANSMISSION OVERTEMP INDICATOR
12 - DOOR AJAR INDICATOR 25 - CHECK GAUGES INDICATOR
13 - ABS INDICATOR
DRINSTRUMENT CLUSTER 8J - 7
INSTRUMENT CLUSTER (Continued)

INDICATORS
Indicators are located in various positions within
the EMIC and are all connected to the EMIC elec-
tronic circuit board. The cargo lamp indicator, door
ajar indicator, high beam indicator, and turn signal
indicators operate based upon hard wired inputs to
the EMIC. The brake indicator is controlled by PCI
data bus messages from the Controller Antilock
Brake (CAB) as well as by hard wired park brake
switch inputs to the EMIC. The seatbelt indicator is
controlled by the EMIC programming, PCI data bus
messages from the Airbag Control Module (ACM),
and a hard wired seat belt switch input to the EMIC.
The Malfunction Indicator Lamp (MIL) is normally
controlled by PCI data bus messages from the Pow-
ertrain Control Module (PCM); however, if the EMIC
loses PCI data bus communication, the EMIC cir-
cuitry will automatically turn the MIL on until PCI
data bus communication is restored. The EMIC uses
PCI data bus messages from the Front Control Mod-
ule (FCM), the PCM, the diesel engine only Engine
Control Module (ECM), the ACM, the CAB, and the
Sentry Key Immobilizer Module (SKIM) to control all
of the remaining indicators.
The various EMIC indicators are controlled by dif-
ferent strategies; some receive fused ignition switch
output from the EMIC circuitry and have a switched
ground, while others are grounded through the EMIC
circuitry and have a switched battery feed. However,
all indicators are completely controlled by the EMIC
microprocessor based upon various hard wired and
electronic message inputs. All indicators are illumi-
nated at a fixed intensity, which is not affected by
the selected illumination intensity of the EMIC gen-
eral illumination lamps.
In addition, certain indicators in this instrument
cluster are automatically configured or self-config-
ured. This feature allows the configurable indicators
to be enabled by the EMIC circuitry for compatibility
with certain optional equipment. The EMIC defaults
for the ABS indicator and airbag indicator are
enabled, and these configuration settings must be
programmatically disabled in the EMIC using a
DRBIIItscan tool for vehicles that do not have this
equipment. The automatically configured or self-con-
figured indicators remain latent in each EMIC at all
times and will be active only when the EMIC
receives the appropriate PCI message inputs for that
optional system or equipment.
The hard wired indicator inputs may be diagnosed
using conventional diagnostic methods. However, the
EMIC circuitry and PCI bus message controlled indi-
cators are diagnosed using the EMIC self-diagnosticactuator test. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING).
Proper testing of the PCI data bus and the electronic
message inputs to the EMIC that control an indicator
requires the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information. Specific details of
the operation for each indicator may be found else-
where in this service information.
CLUSTER ILLUMINATION
The EMIC has several illumination lamps that are
illuminated when the exterior lighting is turned on
with the headlamp switch. The illumination intensity
of these lamps is adjusted when the interior lighting
thumbwheel on the headlamp switch is rotated (down
to dim, up to brighten) to one of six available minor
detent positions. The EMIC monitors a resistor mul-
tiplexed input from the headlamp switch on a dim-
mer input circuit. In response to that input, the
EMIC electronic circuitry converts a 12-volt input it
receives from a fuse in the Integrated Power Module
(IPM) on a hard wired panel lamps dimmer switch
signal circuit into a 12-volt Pulse Width Modulated
(PWM) output. The EMIC uses this PWM output to
power the cluster illumination lamps and the VFD
units on the EMIC circuit board, then provides a syn-
chronized PWM output on the various hard wired
fused panel lamps dimmer switch signal circuits to
control and synchronize the illumination intensity of
other incandescent illumination lamps in the vehicle.
The cluster illumination lamps are grounded at all
times.
The EMIC also sends electronic dimming level
messages over the PCI data bus to other electronic
modules in the vehicle to control and synchronize the
illumination intensity of their VFD units to that of
the EMIC VFD units. In addition, the thumbwheel
on the headlamp switch has a Parade Mode position
to provide a parade mode. The EMIC monitors the
request for this mode from the headlamp switch,
then sends an electronic dimming level message over
the PCI data bus to illuminate all VFD units in the
vehicle at full (daytime) intensity for easier visibility
when driving in daylight with the exterior lighting
turned on.
The hard wired headlamp switch and EMIC panel
lamps dimmer inputs and outputs may be diagnosed
using conventional diagnostic methods. However,
proper testing of the PWM output of the EMIC and
the electronic dimming level messages sent by the
EMIC over the PCI data bus requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
DRINSTRUMENT CLUSTER 8J - 9
INSTRUMENT CLUSTER (Continued)

INPUT AND OUTPUT CIRCUITS
HARD WIRED INPUTS
The hard wired inputs to the EMIC include the fol-
lowing:
²Brake Lamp Switch Output
²Driver Cylinder Lock Switch Sense
²Driver Door Ajar Switch Sense
²Driver Door Lock Switch MUX - with
Power Locks
²Fused B(+) - Ignition-Off Draw
²Fused B(+) - Power Lock Feed - with Power
Locks
²Fused Ignition Switch Output (Accessory-
Run)
²Fused Ignition Switch Output (Off-Run-
Start)
²Fused Ignition Switch Output (Run-Start)
²Headlamp Dimmer Switch MUX
²Headlamp Switch MUX
²Horn Relay Control
²Key-In Ignition Switch Sense
²Left Rear Door Ajar Switch Sense
²Panel Lamps Dimmer Switch Signal
²Park Brake Switch Sense
²Passenger Door Ajar Switch Sense
²Passenger Door Lock Switch MUX - with
Power Locks
²Radio Control MUX
²Right Rear Door Ajar Switch Sense
²RKE Supply - with RKE
²Seat Belt Switch Sense
²Transmission Range Sensor MUX - with
Auto Trans
²Turn/Hazard Switch MUX
²Washer/Beam Select Switch MUX
²Wiper Switch MUX
Refer to the appropriate wiring information for
additional details.
HARD WIRED OUTPUTS
The hard wired outputs of the EMIC include the
following:
²Accessory Switch Bank Illumination Driver
²BTSI Driver - with Auto Trans
²Cargo Lamp Driver
²Dome/Overhead Lamp Driver
²Driver Door Unlock Driver - with Power
Locks
²Headlamp Switch Illumination Driver
²Heated Seat Switch Indicator Driver - with
Heated Seats
²Heater-A/C Control Illumination Driver
²Left Door Lock Driver - with Power Locks
²Left Rear Door Unlock Driver - with Power
Locks²Map/Glove Box Lamp Driver
²Radio Illumination Driver
²Right Door Lock Driver - with Power Locks
²Right Door Unlock Driver - with Power
Locks
²Transfer Case Switch Illumination Driver -
with Four-Wheel Drive
Refer to the appropriate wiring information for
additional details.
GROUNDS
The EMIC receives and supplies a ground path to
several switches and sensors through the following
hard wired circuits:
²Ground - Illumination (2 Circuits)
²Ground - Power Lock - with Power Locks
²Ground - Signal
²Headlamp Switch Return
²Multi-Function Switch Return
²Transmission Range Sensor Return - with
Auto Trans
Refer to the appropriate wiring information for
additional details.
COMMUNICATION
The EMIC has provisions for the following commu-
nication circuits:
²PCI Data Bus
²RKE Program Serial Data - with RKE
²RKE Transmit Serial Data - with RKE
Refer to the appropriate wiring information for
additional details.
DIAGNOSIS AND TESTING - INSTRUMENT
CLUSTER
If all of the instrument cluster gauges and/or indi-
cators are inoperative, refer to PRELIMINARY
DIAGNOSIS. If an individual gauge or Programma-
ble Communications Interface (PCI) data bus mes-
sage-controlled indicator is inoperative, refer to
ACTUATOR TEST. If an individual hard wired indi-
cator is inoperative, refer to the diagnosis and testing
information for that specific indicator.
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.
8J - 10 INSTRUMENT CLUSTERDR
INSTRUMENT CLUSTER (Continued)

CAUTION: Instrument clusters used in this model
automatically configure themselves for compatibil-
ity with the features and optional equipment in the
vehicle in which they are initially installed. The
instrument cluster is programmed to do this by
embedding the Vehicle Identification Number (VIN)
and other information critical to proper cluster
operation into electronic memory. This embedded
information is learned through electronic messages
received from other electronic modules in the vehi-
cle over the Programmable Communications Inter-
face (PCI) data bus, and through certain hard wired
inputs received when the cluster is connected to
the vehicle electrically. Once configured, the instru-
ment cluster memory may be irreparably damaged
and certain irreversible configuration errors may
occur if the cluster is connected electrically to
another vehicle; or, if an electronic module from
another vehicle is connected that provides data to
the instrument cluster (including odometer values)
that conflicts with that which was previously
learned and stored. Therefore, the practice of
exchanging (swapping) instrument clusters and
other electronic modules in this vehicle with those
removed from another vehicle must always be
avoided. Failure to observe this caution may result
in instrument cluster damage, which is not reim-
bursable under the terms of the product warranty.
Service replacement instrument clusters are pro-
vided with the correct VIN, and the certified odom-
eter and engine hours values embedded into cluster
memory, but will otherwise be automatically config-
ured for compatibility with the features and optional
equipment in the vehicle in which they are initially
installed.
NOTE: Certain indicators in this instrument cluster
are automatically configured. This feature allows
those indicators to be activated or deactivated for
compatibility with certain optional equipment. If the
problem being diagnosed involves improper illumi-
nation of the cruise indicator, the electronic throttle
control indicator, the service four-wheel drive indi-
cator, the tow/haul indicator, the transmission over-
temp indicator, the upshift indicator, the security
indicator or the gear selector indicator, disconnect
and isolate the battery negative cable. After about
five minutes, reconnect the battery negative cable
and turn the ignition switch to the On position. The
instrument cluster should automatically relearn the
equipment in the vehicle and properly configure the
configurable indicators accordingly.PRELIMINARY DIAGNOSIS
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Check the fused B(+) fuse (Fuse 51 - 20
ampere) in the Integrated Power Module (IPM). If
OK, go to Step 2. If not OK, repair the shorted circuit
or component as required and replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
(Fuse 51 - 20 ampere) in the IPM. If OK, go to Step
3. If not OK, repair the open fused B(+) circuit
between the IPM and the battery as required.
(3) Disconnect and isolate the battery negative
cable. Remove the instrument cluster. Reconnect the
battery negative cable. Check for battery voltage at
the fused B(+) circuit cavity of the instrument panel
wire harness connector (Connector C1) for the instru-
ment cluster. If OK, go to Step 4. If not OK, repair
the open fused B(+) circuit between the instrument
cluster and the IPM as required.
(4) Check for continuity between the signal ground
circuit cavity of the instrument panel wire harness
connector (Connector C1) for the instrument cluster
and a good ground. There should be continuity. If
OK, refer to ACTUATOR TEST. If not OK, repair the
open ground circuit to ground (G202) as required.
DRINSTRUMENT CLUSTER 8J - 11
INSTRUMENT CLUSTER (Continued)