1998 DODGE RAM 1500 Speed control

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)

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.
ABS INDICATOR
DESCRIPTION
An Antilock Brake System (ABS) indicator is stan-
dard equipment on all instrument clusters (Fig. 8).
However, the instrument cluster can be programmed
to disable this indicator on vehicles that are not
equipped with the ABS or Rear Wheel Anti-Lock
(RWAL) brake systems, which are not available in
some markets. On vehicles equipped with a gasoline
engine, the ABS indicator is located near the lower
edge of the instrument cluster, between the tachom-
eter and the speedometer. On vehicles equipped with
a diesel engine, the ABS indicator is located on the
right side of the instrument cluster, to the right of
the engine temperature gauge. The ABS indicator
consists of a stencil-like cutout of the International
Control and Display Symbol icon for ªFailure of Anti-
lock Braking Systemº in the opaque layer of the
instrument cluster overlay. The dark outer layer of
the overlay prevents the indicator from being clearly
visible when it is not illuminated. An amber Light
Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the icon to appear
in amber through the translucent outer layer of the
overlay when the indicator is illuminated from
behind by the LED, which is soldered onto the
instrument cluster electronic circuit board. The ABS
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The ABS indicator gives an indication to the vehi-
cle operator when the ABS system is faulty or inop-
erative. This indicator is controlled by a transistor on
the instrument cluster circuit board based upon clus-
ter programming and electronic messages received by
the cluster from the Controller Antilock Brake (CAB)
over the Programmable Communications Interface
(PCI) data bus. The ABS indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment cluster logic circuit, and that logic will only
allow this indicator to operate when the instrument
cluster receives a battery current input on the fused
ignition switch output (run-start) circuit. Therefore,
the LED will always be off when the ignition switch
is in any position except On or Start. The LED only
illuminates when it is provided a path to ground by
the instrument cluster transistor. The instrument
cluster will turn on the ABS indicator for the follow-
ing reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the ABS indicator is illu-
minated by the cluster for about two seconds as a
bulb test.
²ABS Lamp-On Message- Each time the clus-
ter receives a lamp-on message from the CAB, the
ABS indicator will be illuminated. The indicator
remains illuminated until the cluster receives a
lamp-off message from the CAB, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Communication Error- If the cluster receives
no lamp-on or lamp-off messages from the CAB for
three consecutive seconds, the ABS indicator is illu-
minated. The indicator remains illuminated until the
cluster receives a valid message from the CAB, or
until the ignition switch is turned to the Off position,
whichever occurs first.
²Actuator Test- Each time the instrument clus-
ter is put through the actuator test, the ABS indica-
tor will be turned on, then off again during the bulb
check portion of the test to confirm the functionality
of the LED and the cluster control circuitry.
²ABS Diagnostic Test- The ABS indicator is
blinked on and off by lamp-on and lamp-off messages
from the CAB during the performance of the ABS
diagnostic tests.
The CAB continually monitors the ABS circuits
and sensors to decide whether the system is in good
operating condition. The CAB then sends the proper
lamp-on or lamp-off messages to the instrument clus-
ter. If the CAB sends a lamp-on message after the
bulb test, it indicates that the CAB has detected a
system malfunction and/or that the ABS system has
become inoperative. The CAB will store a Diagnostic
Trouble Code (DTC) for any malfunction it detects.
Fig. 8 ABS Indicator
DRINSTRUMENT CLUSTER 8J - 17
INSTRUMENT CLUSTER (Continued)

Each time the ABS indicator fails to light due to an
open or short in the cluster ABS indicator circuit, the
cluster sends a message notifying the CAB of the
condition, then the instrument cluster and the CAB
will each store a DTC. For proper diagnosis of the
antilock brake system, the CAB, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the ABS indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
AIRBAG INDICATOR
DESCRIPTION
An airbag indicator is standard equipment on all
instrument clusters (Fig. 9). However, the instrument
cluster can be programmed to disable this indicator
on vehicles that are not equipped with the airbag
system, which is not available in some markets. The
airbag indicator is located near the upper edge of the
instrument cluster, between the tachometer and the
speedometer. The airbag indicator consists of a sten-
cil-like cutout of the words ªAIR BAGº in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from
being clearly visible when it is not illuminated. A red
Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the ªAIR BAGº
text to appear in red through the translucent outer
layer of the overlay when the indicator is illuminated
from behind by the LED, which is soldered onto the
instrument cluster electronic circuit board. The air-
bag indicator is serviced as a unit with the instru-
ment cluster.
OPERATION
The airbag indicator gives an indication to the
vehicle operator when the airbag system is faulty or
inoperative. The airbag indicator is controlled by a
transistor on the instrument cluster circuit board
based upon cluster programming and electronic mes-
sages received by the cluster from the Airbag Control
Module (ACM) over the Programmable Communica-
tions Interface (PCI) data bus. The airbag indicator
Light Emitting Diode (LED) is completely controlled
by the instrument cluster logic circuit, and that logic
will only allow this indicator to operate when the
instrument cluster receives a battery current input
on the fused ignition switch output (run-start) cir-
cuit. Therefore, the LED will always be off when theignition switch is in any position except On or Start.
The LED only illuminates when it is provided a path
to ground by the instrument cluster transistor. The
instrument cluster will turn on the airbag indicator
for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the airbag indicator is illu-
minated for about six seconds. The entire six second
bulb test is a function of the ACM.
²ACM Lamp-On Message- Each time the clus-
ter receives a lamp-on message from the ACM, the
airbag indicator will be illuminated. The indicator
remains illuminated for about twelve seconds or until
the cluster receives a lamp-off message from the
ACM, whichever is longer.
²Communication Error- If the cluster receives
no airbag messages for three consecutive seconds, the
airbag indicator is illuminated. The indicator
remains illuminated until the cluster receives a sin-
gle lamp-off message from the ACM.
²Actuator Test- Each time the cluster is put
through the actuator test, the airbag indicator will be
turned on, then off again during the bulb check por-
tion of the test to confirm the functionality of the
LED and the cluster control circuitry. The actuator
test illumination of the airbag indicator is a function
of the instrument cluster.
The ACM continually monitors the airbag system
circuits and sensors to decide whether the system is
in good operating condition. The ACM then sends the
proper lamp-on or lamp-off messages to the instru-
ment cluster. If the ACM sends a lamp-on message
after the bulb test, it indicates that the ACM has
detected a system malfunction and/or that the air-
bags and seat belt tensioners may not deploy when
required, or may deploy when not required. The ACM
will store a Diagnostic Trouble Code (DTC) for any
malfunction it detects. Each time the airbag indicator
fails to illuminate due to an open or short in the
cluster airbag indicator circuit, the cluster sends a
message notifying the ACM of the condition, the
instrument cluster and the ACM will each store a
DTC, and the cluster will flash the seatbelt indicator
on and off as a backup to notify the vehicle operator.
For proper diagnosis of the airbag system, the ACM,
the PCI data bus, or the electronic message inputs to
the instrument cluster that control the airbag indica-
tor, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
Fig. 9 Airbag Indicator
8J - 18 INSTRUMENT CLUSTERDR
ABS INDICATOR (Continued)

BRAKE/PARK BRAKE
INDICATOR
DESCRIPTION
A brake indicator is standard equipment on all
instrument clusters (Fig. 10). The brake indicator is
located near the lower edge of the instrument cluster,
between the tachometer and the speedometer. The
brake indicator consists of stencil-like cutouts of the
word ªBRAKEº and the International Control and
Display Symbol icon for ªBrake Failureº in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the indicator
from being clearly visible when it is not illuminated.
A red Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the
ªBRAKEº text and the icon to appear in red through
the translucent outer layer of the overlay when the
indicator is illuminated from behind by the LED,
which is soldered onto the instrument cluster elec-
tronic circuit board. The brake indicator is serviced
as a unit with the instrument cluster.
OPERATION
The brake indicator gives an indication to the vehi-
cle operator when the parking brake is applied, when
there are certain brake hydraulic system malfunc-
tions as indicated by a low brake hydraulic fluid level
condition, or when the brake fluid level switch is dis-
connected. The brake indicator can also give an indi-
cation when certain faults are detected in the
Antilock Brake System (ABS). This indicator is con-
trolled by a transistor on the instrument cluster cir-
cuit board based upon cluster programming,
electronic messages received by the cluster from the
Controller Antilock Brake (CAB) over the Program-
mable Communications Interface (PCI) data bus, and
a hard wired input from the park brake switch. The
brake indicator Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logic cir-
cuit, and that logic will only allow this indicator to
operate when the instrument cluster receives a bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the LED will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the brake indicator for the following reasons:²Bulb Test- Each time the ignition switch is
turned to the On position the brake indicator is illu-
minated by the instrument cluster for about two sec-
onds as a bulb test.
²Brake Lamp-On Message- Each time the
cluster receives a lamp-on message from the CAB,
the brake indicator will be illuminated. The CAB can
also send brake lamp-on messages as feedback dur-
ing ABS diagnostic procedures. The indicator
remains illuminated until the cluster receives a
lamp-off message from the CAB, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Park Brake Switch Input- Each time the
cluster detects ground on the park brake switch
sense circuit (park brake switch closed = park brake
applied or not fully released) while the ignition
switch is in the On position, the brake indicator
flashes on and off. The indicator continues to flash
until the park brake switch sense input to the cluster
is an open circuit (park brake switch open = park
brake fully released), or until the ignition switch is
turned to the Off position, whichever occurs first.
²Actuator Test- Each time the instrument clus-
ter is put through the actuator test, the brake indi-
cator will be turned on, then off again during the
bulb check portion of the test to confirm the function-
ality of the LED and the cluster control circuitry.
The park brake switch on the park brake pedal
mechanism provides a hard wired ground input to
the instrument cluster circuitry through the park
brake switch sense circuit whenever the park brake
is applied or not fully released. The CAB continually
monitors the ABS system circuits and sensors,
including the brake fluid level switch on the brake
master cylinder reservoir, to decide whether the sys-
tem is in good operating condition. The CAB then
sends the proper lamp-on or lamp-off messages to the
instrument cluster. If the CAB sends a lamp-on mes-
sage after the bulb test, it indicates that the CAB
has detected a brake hydraulic system malfunction
and/or that the ABS system has become inoperative.
The CAB will store a Diagnostic Trouble Code (DTC)
for any malfunction it detects.
For further diagnosis of the brake indicator or the
instrument cluster circuitry that controls the LED,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). The park brake
switch input to the instrument cluster can be diag-
nosed using conventional diagnostic tools and meth-
ods. For proper diagnosis of the brake fluid level
switch, the ABS, the CAB, the PCI data bus, or the
electronic message inputs to the instrument cluster
that control the brake indicator, a DRBIIItscan tool
is required. Refer to the appropriate diagnostic infor-
mation.
Fig. 10 Brake Indicator
DRINSTRUMENT CLUSTER 8J - 19

cluster programming, a hard wired multiplex input
received by the cluster from the headlamp panel
lamps dimmer switch on the headlamp dimmer
switch mux circuit, and electronic unlock request
messages received from the optional Remote Keyless
Entry (RKE) receiver module. The cargo lamp indica-
tor Light Emitting Diode (LED) is completely con-
trolled by the instrument cluster logic circuit, and
that logic will allow only this indicator to operate
whenever the instrument cluster receives a battery
current input on the fused ignition switch output
(run-start) circuit. Therefore, the LED will always be
off when the ignition switch is in any position except
On or Start. The LED only illuminates when it is
provided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
cargo lamp indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the cargo lamp indicator is
illuminated for about two seconds as a bulb test.
²Cargo Lamp-On Input- Each time the cluster
detects a cargo lamp-on input from the headlamp
switch on the headlamp dimmer switch mux circuit,
the cargo lamp and the cargo lamp indicator will be
illuminated. The cargo lamp and indicator remain
illuminated until the cluster receives a cargo lamp-off
input from the headlamp switch, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Actuator Test- Each time the cluster is put
through the actuator test, the cargo lamp indicator
will be turned on, then off again during the bulb
check portion of the test to confirm the functionality
of the LED and the cluster control circuitry.
The instrument cluster continually monitors the
headlamp dimmer switch circuit to determine the
proper interior lamps features and panel lamps illu-
mination levels to provide. The cluster then energizes
and de-energizes a low side driver circuit to control
the exterior cargo lamp. Each time the instrument
cluster energizes the cargo lamp driver and the igni-
tion switch is in the On or start positions, the cluster
also turns on the cargo lamp indicator. For further
diagnosis of the cargo lamp indicator or the instru-
ment cluster circuitry that controls the indicator,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). For proper
diagnosis of the cargo lamp or the headlamp switch
inputs to the instrument cluster that control the
cargo lamp indicator, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information.CHECK GAUGES INDICATOR
DESCRIPTION
A check gauges indicator is standard equipment on
all instrument clusters (Fig. 12). On vehicles
equipped with a gasoline engine, the check gauges
indicator is located near the lower edge of the instru-
ment cluster, between the tachometer and the speed-
ometer. On vehicles equipped with a diesel engine,
the check gauges indicator is located on the left side
of the instrument cluster, to the left of the voltage
gauge. The check gauges indicator consists of a sten-
cil-like cutout of the words ªCHECK GAGESº in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the indicator
from being clearly visible when it is not illuminated.
A red Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the
ªCHECK GAGESº text to appear in red through the
translucent outer layer of the overlay when the indi-
cator is illuminated from behind by the LED, which
is soldered onto the instrument cluster electronic cir-
cuit board. The check gauges indicator is serviced as
a unit with the instrument cluster.
OPERATION
The check gauges indicator gives an indication to
the vehicle operator when certain instrument cluster
gauge readings reflect a condition requiring immedi-
ate attention. This indicator is controlled by a tran-
sistor on the instrument cluster circuit board based
upon cluster programming and electronic messages
received by the cluster from the Powertrain Control
Module (PCM) on vehicles equipped with a gasoline
engine, or from the Engine Control Module (ECM) on
vehicles equipped with a diesel engine over the Pro-
grammable Communications Interface (PCI) data
bus. The check gauges indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment cluster logic circuit, and that logic will only
allow this indicator to operate when the instrument
cluster receives a battery current input on the fused
ignition switch output (run-start) circuit. Therefore,
the LED will always be off when the ignition switch
is in any position except On or Start. The LED only
illuminates when it is provided a path to ground by
the instrument cluster transistor. The instrument
cluster will turn on the check gauges indicator for
the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the check gauges indicator
is illuminated for about two seconds as a bulb test.
Fig. 12 Check Gauges Indicator
DRINSTRUMENT CLUSTER 8J - 21
CARGO LAMP INDICATOR (Continued)

²Engine Temperature High Message- Each
time the cluster receives a message from the PCM or
ECM indicating the engine coolant temperature of a
gasoline engine is about 122É C (252É F) or higher, or
of a diesel engine is about 112É C (233É F) or higher,
the check gauges indicator will be illuminated. The
indicator remains illuminated until the cluster
receives a message from the PCM or ECM indicating
that the engine coolant temperature of a gasoline
engine is below about 122É C (252É F), or of a diesel
engine is below about 112É C (233É F), or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM or
ECM indicating the engine oil pressure is about 41
kPa (6 psi) or lower, the check gauges indicator will
be illuminated. The indicator remains illuminated
until the cluster receives a message from the PCM or
ECM indicating that the engine oil pressure is above
about 41 kPa (6 psi), or until the ignition switch is
turned to the Off position, whichever occurs first.
The cluster will only turn the indicator on in
response to an engine oil pressure low message if the
engine speed is greater than zero.
²System Voltage Low (Charge Fail) Message
- Each time the cluster receives a message from the
PCM or ECM indicating the electrical system voltage
is less than about 11.5 volts (charge fail condition),
the check gauges indicator will be illuminated. The
indicator remains illuminated until the cluster
receives a message from the PCM or ECM indicating
the electrical system voltage is greater than about
12.0 volts (but less than 16.0 volts), or until the igni-
tion switch is turned to the Off position, whichever
occurs first.
²System Voltage High Message- Each time
the cluster receives a message from the PCM or ECM
indicating the electrical system voltage is greater
than about 16.0 volts, the check gauges indicator will
be illuminated. The indicator remains illuminated
until the cluster receives a message from the PCM or
ECM indicating the electrical system voltage is less
than about 15.5 volts (but greater than 11.5 volts), or
until the ignition switch is turned to the Off position,
whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the check gauges indicator
will be turned on, then off again during the bulb
check portion of the test to confirm the functionality
of the LED and the cluster control circuitry.
On vehicles with a gasoline engine, the PCM con-
tinually monitors the engine temperature, oil pres-
sure, and electrical system voltage, then sends the
proper messages to the instrument cluster. On vehi-
cles with a diesel engine, the ECM continually mon-itors the engine temperature, oil pressure, and
electrical system voltage, then sends the proper mes-
sages to the instrument cluster. For further diagnosis
of the check gauges indicator or the instrument clus-
ter circuitry that controls the LED, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
PCM, the ECM, the PCI data bus, or the electronic
message inputs to the instrument cluster that control
the check gauges indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
CRUISE INDICATOR
DESCRIPTION
A cruise indicator is standard equipment on all
instrument clusters (Fig. 13). However, on vehicles
not equipped with the optional speed control system,
this indicator is electronically disabled. The cruise
indicator consists of the word ªCRUISEº, which
appears in the lower portion of the gear selector indi-
cator Vacuum-Fluorescent Display (VFD) unit. The
VFD is soldered onto the cluster electronic circuit
board and is visible through a window with a smoked
clear lens located on the lower edge of the speedom-
eter gauge dial face of the cluster overlay. The dark
lens over the VFD prevents the indicator from being
clearly visible when it is not illuminated. The word
ªCRUISEº appears in a blue-green color and at the
same lighting level as the gear selector indicator
information when it is illuminated by the instrument
cluster electronic circuit board. The cruise indicator
is serviced as a unit with the VFD in the instrument
cluster.
OPERATION
The cruise indicator gives an indication to the vehi-
cle operator when the speed control system is turned
On, regardless of whether the speed control is
engaged. This indicator is controlled by the instru-
ment cluster circuit board based upon cluster pro-
gramming and electronic messages received by the
cluster from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus. The cruise indicator is completely
controlled by the instrument cluster logic circuit, and
that logic will only allow this indicator to operate
when the instrument cluster receives a battery cur-
rent input on the fused ignition switch output (run-
start) circuit. Therefore, the indicator will always be
Fig. 13 Cruise Indicator
8J - 22 INSTRUMENT CLUSTERDR
CHECK GAUGES INDICATOR (Continued)