wheel DODGE RAM 2003 Service Repair Manual

HORN
TABLE OF CONTENTS
page page
HORN SYSTEM
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - HORN SYSTEM . . . 1
HORN
DIAGNOSIS AND TESTING - HORN..........1REMOVAL.............................2
INSTALLATION..........................2
HORN SWITCH
DESCRIPTION..........................2
DIAGNOSIS AND TESTING - HORN SWITCH . . . 2
HORN SYSTEM
DESCRIPTION
The dual-note horn system features dual electro-
magnetic horn units. The horn system includes the
following major components:
²Horn- The two horns are located on the left
side of the engine compartment below the Integrated
Power Module (IPM).
²Horn Switch- The horn switch is molded into
the driver airbag trim cover.
OPERATION
The horn system operates on battery current
received through a fuse in the Integrated Power
Module (IPM). The horn system circuit is designed so
that the system will remain operational, regardless
of the ignition switch position.
DIAGNOSIS AND TESTING - HORN SYSTEM
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual. The DRBIIItscan
tool can provide confirmation that the PCI data
bus is functional, that all of the electronic mod-
ules are sending and receiving the proper mes-
sages on the PCI data bus, and that the horns
are being sent the proper hard wired outputs
for them to perform their functions.
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.
In most cases, any problem involving continually
sounding horns can be quickly alleviated by removing
the horn fuse from the Integrated Power Module
(IPM).WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
HORN
DIAGNOSIS AND TESTING - HORN
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual. The DRBIIItscan
tool can provide confirmation that the PCI data
bus is functional, that all of the electronic mod-
ules are sending and receiving the proper mes-
sages on the PCI data bus, and that the horns
are being sent the proper hard wired outputs
for them to perform their functions.
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.
DRHORN 8H - 1

WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the wire harness connectors from
the horns (Fig. 1).
(3) Remove mounting bolt and remove horns.
INSTALLATION
(1) Position horns and install mounting bolt.
Tighten the bolt to 10 N´m (85 in. lbs.).
(2) Connect wire harness connectors.
(3) Connect battery negative cable.
HORN SWITCH
DESCRIPTION
The horn switch is molded into the driver airbag.
The horn switch can not be serviced separately. For
service procedures, (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL).
DIAGNOSIS AND TESTING - HORN SWITCH
The most reliable, efficient, and accurate
means to diagnose the horn system requires the
use of a DRBIIItscan tool and the proper Diag-
nostic Procedures manual. The DRBIIItscan
tool can provide confirmation that the PCI data
bus is functional, that all of the electronic mod-
ules are sending and receiving the proper mes-
sages on the PCI data bus, and that the horns
are being sent the proper hard wired outputs
for them to perform their functions.
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
Fig. 1 HORN
1 - WIRE HARNESS CONNECTORS
2 - HORNS
3 - MOUNTING BOLT
8H - 2 HORNDR
HORN (Continued)

(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 5). Refer to label on PDC cover
for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
CAMSHAFT POSITION
SENSOR
DESCRIPTION
3.7L V-6
The Camshaft Position Sensor (CMP) on the 3.7L
6-cylinder engine is bolted to the right-front side of
the right cylinder head.
4.7L V-8
The Camshaft Position Sensor (CMP) on the 4.7L
V-8 engine is bolted to the right-front side of the
right cylinder head.
5.7L V-8
The Camshaft Position Sensor (CMP) on the 5.7L
V-8 engine is located below the generator on the tim-
ing chain / case cover on the right/front side of
engine.
5.9L Diesel
The Camshaft Position Sensor (CMP) on the 5.9L
diesel engine is located below the fuel injection
pump. It is bolted to the back of the timing gear
cover.
5.9L V-8 Gas
The Camshaft Position Sensor (CMP) on the 5.9L
V-8 engine is located inside the distributor.
8.0L V±10
The Camshaft Position Sensor (CMP) on the 8.0L
V-10 engine is located on the timing chain / case
cover on the left/front side of engine.
OPERATION
3.7L V-6
The Camshaft Position Sensor (CMP) sensor on the
3.7L V-6 engine contains a hall effect device referred
to as a sync signal generator. A rotating target wheel
(tonewheel) for the CMP is located at the front of the
camshaft for the right cylinder head (Fig. 6). This
sync signal generator detects notches located on a
tonewheel. As the tonewheel rotates, the notches
pass through the sync signal generator. The signal
from the CMP sensor is used in conjunction with the
Crankshaft Position Sensor (CKP) to differentiate
between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
When the leading edge of the tonewheel notch
enters the tip of the CMP, the interruption of mag-
netic field causes the voltage to switch high, result-
ing in a sync signal of approximately 5 volts.
When the trailing edge of the tonewheel notch
leaves then tip of the CMP, the change of the mag-
netic field causes the sync signal voltage to switch
low to 0 volts.
4.7L V-8
The CMP sensor on the 4.7L engine contains a hall
effect device called a sync signal generator to gener-
ate a fuel sync signal. This sync signal generator
detects notches located on a tonewheel. The tone-
wheel is located at the front of the camshaft for the
right cylinder head (Fig. 7). As the tonewheel rotates,
the notches pass through the sync signal generator.
The pattern of the notches (viewed counter-clockwise
from front of engine) is: 1 notch, 2 notches, 3 notches,
Fig. 5 PDC LOCATION
1 - BATTERY
2 - PDC (POWER DISTRIBUTION CENTER)
8I - 8 IGNITION CONTROLDR
AUTOMATIC SHUT DOWN RELAY (Continued)

3 notches, 2 notches 1 notch, 3 notches and 1 notch.
The signal from the CMP sensor is used in conjunc-
tion with the crankshaft position sensor to differenti-
ate between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
5.7L V-8
The CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders. The sensor generates electrical pulses. These
pulses (signals) are sent to the Powertrain Control
Module (PCM). The PCM will then determine crank-
shaft position from both the camshaft position sensor
and crankshaft position sensor.
The tonewheel is located at the front of the cam-
shaft (Fig. 8). As the tonewheel rotates, notches (Fig.
8) pass through the sync signal generator.
When the cam gear is rotating, the sensor will
detect the notches. Input voltage from the sensor to
the PCM will then switch from a low (approximately
0.3 volts) to a high (approximately 5 volts). When the
sensor detects a notch has passed, the input voltage
switches back low to approximately 0.3 volts.
Fig. 6 CMP OPERATION- 3.7L V-6
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CMP
4 - TONEWHEEL (TARGET WHEEL)
Fig. 7 CMP AND TONEWHEEL OPERATION - 4.7L
V-8
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CAMSHAFT POSITION SENSOR
4 - TONEWHEEL
Fig. 8 CMP OPERATION - 5.7L ENGINE
1 - TIMING CHAIN COVER
2 - TONEWHEEL
3 - NOTCHES
DRIGNITION CONTROL 8I - 9
CAMSHAFT POSITION SENSOR (Continued)

5.9L V-8 Gas
The CMP sensor on the 5.9L V-8 engine contains a
hall effect device called a sync signal generator to
generate a fuel sync signal. This sync signal genera-
tor detects a rotating pulse ring (shutter) (Fig. 9) on
the distributor shaft. The pulse ring rotates 180
degrees through the sync signal generator. Its signal
is used in conjunction with the Crankshaft Position
(CKP) sensor to differentiate between fuel injection
and spark events. It is also used to synchronize the
fuel injectors with their respective cylinders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi-
mately 5 volts.
When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig-
nal voltage to switch low to 0 volts.
5.9L Diesel
The Camshaft Position Sensor (CMP) contains a
hall effect device. A rotating target wheel (tonewheel)
for the CMP is located on the front timing gear. This
hall effect device detects notches located on the tone-
wheel. As the tonewheel rotates, the notches pass the
tip of the CMP.
When the leading edge of the tonewheel notch
passes the tip of the CMP, the following occurs: The
interruption of magnetic field causes the voltage to
switch high resulting in a signal of approximately 5
volts.
When the trailing edge of the tonewheel notch
passes the tip of the CMP, the following occurs: Thechange of the magnetic field causes the signal voltage
to switch low to 0 volts.
The CMP (Fig. 10) provides a signal to the Engine
Control Module (ECM) at all times when the engine
is running. The ECM uses the CMP information pri-
marily on engine start-up. Once the engine is run-
ning, the ECM uses the CMP as a backup sensor for
engine speed. The Crankshaft Position Sensor (CKP)
is the primary engine speed indicator for the engine
after the engine is running.
8.0L V-10
The CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders. The sensor generates electrical pulses. These
pulses (signals) are sent to the Powertrain Control
Module (PCM). The PCM will then determine crank-
shaft position from both the camshaft position sensor
and crankshaft position sensor.
A low and high area are machined into the cam-
shaft drive gear (Fig. 11). The sensor is positioned in
the timing gear cover so that a small air gap (Fig. 11)
exists between the face of sensor and the high
machined area of cam gear.
Fig. 9 CMP / PULSE RING - 5.9L GAS ENGINE
1 - SYNC SIGNAL GENERATOR
2 - CAMSHAFT POSITION SENSOR
3 - PULSE RING
4 - DISTRIBUTOR ASSEMBLY
Fig. 10 5.9L DIESEL CMP
1 - CMP
2 - FUEL INJECTION PUMP (BOTTOM)
3 - ELECTRONIC CONTROL MODULE (ECM)
4 - ECM ELEC. CONNECTOR
5 - CMP ELEC. CONNECTOR
6 - CMP MOUNTING BOLT
7 - BACK OF TIMING GEAR COVER
8I - 10 IGNITION CONTROLDR
CAMSHAFT POSITION SENSOR (Continued)

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. The torque for the knock senor bolt is rela-
tively light for an 8mm bolt.
NOTE: 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.
(3) Install and tighten mounting bolts. Refer to
torque specification.
(4) Install intake manifold. Refer to Engine sec-
tion.
(5) Connect knock sensor wiring harness to engine
harness at rear of intake manifold.
5.7L V-8
(1) Thoroughly clean knock sensor mounting hole.
(2) Install sensor into cylinder block.
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. The torque for the knock senor bolt is rela-
tively light for an 8mm bolt.
NOTE: 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.
(3) Install and tighten mounting bolt. Refer to
torque specification.
(4) Install electrical connector to sensor.
SPARK PLUG
DESCRIPTION
Resistor type spark plugs are used on all engines.
Sixteen spark plugs (2 per cylinder) are used with
5.7L V-8 engines.
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS
To prevent possible pre-ignition and/or mechanical
engine damage, the correct type/heat range/number
spark plug must be used.
Always use the recommended torque when tighten-
ing spark plugs. Incorrect torque can distort the
spark plug and change plug gap. It can also pull the
plug threads and do possible damage to both the
spark plug and the cylinder head.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. A sin-
gle plug displaying an abnormal condition indicates
that a problem exists in the corresponding cylinder.
Replace spark plugs at the intervals recommended in
the Lubrication and Maintenance section.
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective, carbon or oil
fouled.
CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will
remain on the spark plug insulator and will cause
plug misfire.
Spark plug resistance values range from 6,000 to
20,000 ohms (when checked with at least a 1000 volt
spark plug tester).Do not use an ohmmeter to
check the resistance values of the spark plugs.
Inaccurate readings will result.
NORMAL OPERATING
The few deposits present on the spark plug will
probably be light tan or slightly gray in color. This is
evident with most grades of commercial gasoline
(Fig. 42). There will not be evidence of electrode
burning. Gap growth will not average more than
approximately 0.025 mm (.001 in) per 3200 km (2000
miles) of operation. Spark plugs that have normal
wear can usually be cleaned, have the electrodes
filed, have the gap set and then be installed.
Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with MMT
causes the entire tip of the spark plug to be coated
with a rust colored deposit. This rust color can be
misdiagnosed as being caused by coolant in the com-
bustion chamber. Spark plug performance may be
affected by MMT deposits.
DRIGNITION CONTROL 8I - 27
KNOCK SENSOR (Continued)

8.0L V-10
(1) Always remove spark plug or ignition coil
cables by grasping at the cable boot (Fig. 50). Turn
the cable boot 1/2 turn and pull straight back in a
steady motion. Never pull directly on the cable.
Internal damage to cable will result.
(2) Prior to removing the spark plug, spray com-
pressed air around the spark plug hole and the area
around the spark plug. This will help prevent foreign
material from entering the combustion chamber.
(3) Remove the spark plug using a quality socket
with a rubber or foam insert.
(4) Inspect the spark plug condition. Refer to Diag-
nostics and Testing - Spark Plug Conditions.
CLEANING
CLEANING AND ADJUSTMENT
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean-
ing, file center electrode flat with a small point file or
jewelers file before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean spark plugs. Metallic deposits will remain
on spark plug insulator and will cause plug misfire.
Adjust spark plug gap with a gap gauging tool
(Fig. 51).
INSTALLATION
3.7L V-6
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
sure the plugs do not drop into the plug wells as elec-
trodes can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten spark plugs. Refer to torque specifica-
tions.
(3) Before installing ignition coil(s), check condi-
tion of coil o-ring and replace as necessary. To aid in
coil installation, apply silicone to coil o-ring.
(4) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.
Fig. 50 CABLE REMOVAL - 5.9L / 8.0L
1 - SPARK PLUG CABLE AND BOOT
2 - SPARK PLUG BOOT PULLER
3 - TWIST AND PULL
4 - SPARK PLUG
Fig. 51 SETTING SPARK PLUG GAP - TYPICAL
1 - GAUGE TOOL
2 - SPARK PLUG
DRIGNITION CONTROL 8I - 31
SPARK PLUG (Continued)

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 appro-
priate 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 Indicator
²Electronic 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)
²Overdrive-Off Indicator (with Automatic
Transmission only)
²Seatbelt Indicator
²Security Indicator (with Sentry Key Immo-
bilizer & Vehicle Theft Security Systems only)
²Service Four-Wheel Drive Indicator (with
Four-Wheel Drive 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
board hardware, the cluster overlay, or the EMIC
housing are damaged or faulty, the entire EMIC mod-
DRINSTRUMENT CLUSTER 8J - 5
INSTRUMENT CLUSTER (Continued)

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-diagnostic
actuator 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 ofthe 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.
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
DRINSTRUMENT CLUSTER 8J - 9
INSTRUMENT CLUSTER (Continued)

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
Locks
²Map/Glove Box Lamp Driver²Radio 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)