check engine light DODGE RAM 2001 Service Owner's Guide

SPARK PLUG
DESCRIPTION
The 3.9L V-6 and 5.2L/5.9L V-8 engines use resis-
tor type spark plugs. The 8.0L V-10 engine uses
inductive type spark plugs.
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.
OPERATION
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
Group O, Lubrication and Maintenance
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective, carbon or oil
fouled. Also refer to Spark Plug Conditions.
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.
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS
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. 29). 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.
Fig. 28 Spark Plug Cable OrderÐ8.0L V-10 Engine
Fig. 29 Normal Operation and Cold (Carbon) Fouling
1 - NORMAL
2 - DRY BLACK DEPOSITS
3 - COLD (CARBON) FOULING
8I - 16 IGNITION CONTROLBR/BE
IGNITION COIL (Continued)

With the engine running, remove spark plug cable
from spark plug (one at a time) and hold next to a
good engine ground. If the cable and spark plug are
in good condition, the engine rpm should drop and
the engine will run poorly. If engine rpm does not
drop, the cable and/or spark plug may not be operat-
ing properly and should be replaced. Also check
engine cylinder compression.
With the engine not running, connect one end of a
test probe to a good ground. Start the engine and run
the other end of the test probe along the entire
length of all spark plug cables. If cables are cracked
or punctured, there will be a noticeable spark jump
from the damaged area to the test probe. The cable
running from the ignition coil to the distributor cap
can be checked in the same manner. Cracked, dam-
aged or faulty cables should be replaced with resis-
tance type cable. This can be identified by the words
ELECTRONIC SUPPRESSION printed on the cable
jacket.
Use an ohmmeter to test for open circuits, exces-
sive resistance or loose terminals. If equipped,
remove the distributor cap from the distributor.Do
not remove cables from cap.Remove cable from
spark plug. Connect ohmmeter to spark plug termi-
nal end of cable and to corresponding electrode in
distributor cap. Resistance should be 250 to 1000
Ohms per inch of cable. If not, remove cable from dis-
tributor cap tower and connect ohmmeter to the ter-
minal ends of cable. If resistance is not within
specifications as found in the SPARK PLUG CABLE
RESISTANCE chart, replace the cable. Test all spark
plug cables in this manner.
SPARK PLUG CABLE RESISTANCE
MINIMUM MAXIMUM
250 Ohms Per Inch 1000 Ohms Per Inch
3000 Ohms Per Foot 12,000 Ohms Per Foot
To test ignition coil-to-distributor cap cable, do not
remove the cable from the cap. Connect ohmmeter to
rotor button (center contact) of distributor cap and
terminal at ignition coil end of cable. If resistance is
not within specifications as found in the Spark Plug
Cable Resistance chart, remove the cable from the
distributor cap. Connect the ohmmeter to the termi-
nal ends of the cable. If resistance is not within spec-
ifications as found in the Spark Plug Cable
Resistance chart, replace the cable. Inspect the igni-
tion coil tower for cracks, burns or corrosion.
REMOVAL
CAUTION: When disconnecting a high voltage cable
from a spark plug or from the distributor cap, twist
the rubber boot slightly (1/2 turn) to break it loose
(Fig. 38). Grasp the boot (not the cable) and pull it
off with a steady, even force.
INSTALLATION
Install cables into the proper engine cylinder firing
order (Fig. 39), (Fig. 40) or (Fig. 41).
When replacing the spark plug and coil cables,
route the cables correctly and secure in the proper
retainers. Failure to route the cables properly can
cause the radio to reproduce ignition noise. It could
also cause cross ignition of the plugs or short circuit
the cables to ground.
Fig. 37 Heat ShieldsÐ3.9L/5.2L/5.9L Engines
1 - AIR GAP
2 - SPARK PLUG BOOT HEAT SHIELD
Fig. 38 Cable Removal
1 - SPARK PLUG CABLE AND BOOT
2 - SPARK PLUG BOOT PULLER
3 - TWIST AND PULL
4 - SPARK PLUG
8I - 20 IGNITION CONTROLBR/BE
SPARK PLUG CABLE (Continued)

(7) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Reinstall the instrument cluster. Reconnect the bat-
tery negative cable. Turn the ignition switch to the
On position. Set the park brake. The brake indicator
in the instrument cluster should light. If OK, go to
Step 8. If not OK, go to Step 9.
(8) Turn the ignition switch to the Off position.
Turn on the park lamps and adjust the panel lamps
dimmer thumbwheel in the headlamp switch to the
full bright position. The cluster illumination lamps
should light. If OK, go to Step 10. If not OK, repair
the open ground circuit (Z3) between the instrument
cluster and ground (G201) as required.
(9) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster. Connect the battery
negative cable. Turn the ignition switch to the On
position. Check for battery voltage at the fused igni-
tion switch output (st-run) circuit cavity of the
instrument panel wire harness connector (Connector
C1). If OK, refer to ACTUATOR TEST . If not OK,
repair the open fused ignition switch output (st-run)
circuit between the instrument cluster and the JB as
required.
(10) Disconnect and isolate the battery negative
cable. Remove the instrument cluster. Check for con-
tinuity between the ground circuit (Z2) cavity of the
instrument panel wire harness connector (Connector
C1) and a good ground. There should be continuity. If
OK, refer to ACTUATOR TEST . If not OK, repair
the open ground circuit to ground (G200) as required.
ACTUATOR TEST
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, 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.
The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a self-
diagnostic test that will confirm that the instrument
cluster circuitry, the gauges, and the CCD data bus
message-controlled indicators are capable of operat-
ing as designed. During the actuator test the instru-
ment cluster circuitry position each of the gauge
needles at various calibration points, illuminate each
of the segments in the Vacuum-Fluorescent Display
(VFD), and turn all of the CCD data bus message-
controlled indicators on and off.
Successful completion of the actuator test will con-
firm that the instrument cluster is operational. How-
ever, there may still be a problem with the CCD data
bus, the Powertrain Control Module (PCM), the
Engine Control Module (ECM), the Airbag Control
Module (ACM), the Controller Anti-lock Brake (CAB),
or the inputs to one of these electronic control mod-
ules. Use a DRBIIItscan tool to diagnose these com-
ponents. Refer to the appropriate diagnostic
information.
(1) Begin the test with the ignition switch in the
Off position.
(2) Depress the odometer/trip odometer switch but-
ton.
(3) While still holding the odometer/trip odometer
switch button depressed, turn the ignition switch to
the On position, but do not start the engine.
(4) Keep the odometer/trip odometer switch button
depressed for about ten seconds, untilCHEC
appears in the odometer display, then release the
odometer/trip odometer switch button.
(5) A series of three-digit numeric failure messages
may appear in the odometer display, depending upon
the failure mode. If a failure message appears, refer
to the Instrument Cluster Failure Message chart for
the description and proper correction. If no failure
message appears, the actuator test will proceed as
described in Step 6.
BR/BEINSTRUMENT CLUSTER 8J - 7
INSTRUMENT CLUSTER (Continued)

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 cir-
cuit, the cluster sends a message notifying the ACM
of the condition, the ACM will store a DTC, and the
cluster begins blinking the seat belt indicator. (Refer
to 8 - ELECTRICAL/INSTRUMENT CLUSTER/
SEATBELT INDICATOR - OPERATION). For proper
diagnosis of the airbag system, the ACM, the CCD
data bus, or the message inputs to the instrument
cluster that control the airbag indicator, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
BRAKE/PARK BRAKE
INDICATOR
DESCRIPTION
A brake indicator is standard equipment on all
instrument clusters. The brake indicator is located
near the lower edge of the instrument cluster overlay,
to the right of center. The brake indicator consists of
a stenciled cutout of the word ªBRAKEº 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 lens behind the cutout in the opaque layer of
the overlay causes the ªBRAKEº text to appear in
red through the translucent outer layer of the over-
lay when it is illuminated from behind by a Light
Emitting Diode (LED) soldered onto the instrument
cluster electronic 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, or
when there are certain brake hydraulic system mal-
functions. This indicator is controlled by a transistor
on the instrument cluster circuit board based upon a
hard wired input to the instrument cluster, cluster
programming, and electronic messages received by
the cluster from the Controller Antilock Brake (CAB)
over the Chrysler Collision Detection (CCD) data bus.
The brake indicator Light Emitting Diode (LED)
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (st-run) circuit whenever the ignition
switch is in the On or Start positions; therefore, the
LED will always be off when the ignition switch is in
any position except On or Start. The LED only illu-
minates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the brake indicator for the following rea-
sons: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 four sec-
onds as a bulb test.
²Park Brake-On- If the park brake is applied
or not fully released with the ignition switch in the
On position, the brake indicator is illuminated solid.
The brake indicator will blink on and off repeatedly
when the park brake is applied or not fully released
and the ignition switch is in the On position if a
vehicle with an automatic transmission is not in
Park or Neutral, or if the engine is running on vehi-
cles with a manual transmission.
²Brake Lamp-On Message- Each time the
cluster receives a lamp-on message from the CAB,
the brake 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.
²Actuator Test- Each time the instrument clus-
ter is put through the actuator test, the brake indi-
cator will be turned on during the bulb check portion
of the test to confirm the functionality 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 brake pressure switch on the brake
combination valve to determine if the pressures in
the two halves of the split brake hydraulic system
are unequal. The CAB then sends the proper lamp-on
or lamp-off messages to the instrument cluster. If the
CAB sends a lamp-on message after the bulb test, it
indicates that the CAB has detected a brake hydrau-
lic system malfunction and/or that the ABS system
has become inoperative. The CAB will store a Diag-
nostic Trouble Code (DTC) for any malfunction it
detects. The park brake switch input to the instru-
ment cluster can be diagnosed using conventional
diagnostic tools and methods. For proper diagnosis of
the antilock brake system, the CAB, the CCD data
bus, or the message inputs to the instrument cluster
that control the brake indicator, a DRBIIItscan tool
is required. Refer to the appropriate diagnostic infor-
mation.
DIAGNOSIS AND TESTING - BRAKE INDICATOR
The diagnosis found here addresses an inoperative
brake indicator condition. If the brake indicator
comes on or stays on with the ignition switch in the
On position and the park brake released, or comes on
while driving, the brake system must be diagnosed
and repaired prior to performing the following tests.
8J - 16 INSTRUMENT CLUSTERBR/BE
AIRBAG INDICATOR (Continued)

(Refer to 5 - BRAKES - DIAGNOSIS AND TEST-
ING). If no brake system problem is found, the fol-
lowing procedure will help locate a faulty park brake
switch or park brake switch sense circuit. Refer to
the appropriate wiring information. The wiring infor-
mation 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 con-
nectors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, 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.
(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the park brake switch from the switch
terminal. With the park brake released, check for
continuity between the park brake switch terminal
and a good ground. There should be no continuity. If
OK, go to Step 2. If not OK, adjust or replace the
faulty park brake switch.
(2) Remove the instrument cluster from the instru-
ment panel. With the park brake switch still discon-
nected, check for continuity between the park brake
switch sense circuit cavity of the instrument panel
wire harness connector for the park brake switch and
a good ground. There should be no continuity. If OK,
go to Step 3. If not OK, repair the shorted park
brake switch sense circuit between the park brake
switch and the instrument cluster as required.
(3) Check for continuity between the park brake
switch sense circuit cavities of the instrument panel
wire harness connector for the park brake switch and
the instrument panel wire harness connector (Con-
nector C1) for the instrument cluster. There should
be continuity. If OK, proceed with diagnosis of the
instrument cluster. (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND TEST-
ING). If not OK, repair the open park brake switch
sense circuit between the park brake switch and the
instrument cluster as required.CHECK GAUGES INDICATOR
DESCRIPTION
A check gauges indicator is standard equipment on
all instrument clusters. The check gauges indicator is
located on the lower edge of the instrument cluster
overlay, to the right of center. The check gauges indi-
cator consists of a stenciled cutout of the words
ªCHECK GAGESº in the opaque layer of the instru-
ment cluster overlay. The dark outer layer of the
overlay prevents the indicator from being clearly vis-
ible when the it is not illuminated. A red lens 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
indicator is illuminated from behind by a Light Emit-
ting Diode (LED) soldered onto the instrument clus-
ter electronic circuit 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 the cluster programming and electronic mes-
sages received by the cluster from the Powertrain
Control Module (PCM) over the Chrysler Collision
Detection (CCD) data bus. The check gauges indica-
tor Light Emitting Diode (LED) receives battery cur-
rent on the instrument cluster electronic circuit
board through the fused ignition switch output (st-
run) circuit whenever the ignition switch is in the On
or Start positions; 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.
²Engine Temperature High Message- Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature of a gaso-
line engine is about 122É C (253É F) or higher, or a
diesel engine is about 112É C (233É F) or higher, the
check gauges indicator will be illuminated. The indi-
cator remains illuminated until the cluster receives a
message from the PCM indicating that the tempera-
ture of a gasoline engine is about 119É C (246É F) or
lower, a diesel engine is about 109É C (226É F) or
lower, or until the ignition switch is turned to the Off
position, whichever occurs first.
BR/BEINSTRUMENT CLUSTER 8J - 17
BRAKE/PARK BRAKE INDICATOR (Continued)

²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure of a gasoline
engine is about 3.45 kPa (0.5 psi) or lower, or a diesel
engine is about 51.71 kPa (7.5 psi) or lower, the
check gauges indicator will be illuminated. The indi-
cator remains illuminated until the cluster receives a
message from the PCM indicating that the engine oil
pressure of a gasoline engine is above 3.45 kPa (0.5
psi), a diesel engine is above 51.71 kPa (7.5 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 Message- Each time the
cluster receives a message from the PCM indicating
the electrical system voltage is less than 11.5 volts,
the check gauges indicator will be illuminated. The
indicator remains illuminated until the cluster
receives a message from the PCM indicating the elec-
trical system voltage is greater than 12.0 volts (but
less than 16.6 volts), or until the ignition switch is
turned to the Off position, whichever occurs first.
²System Voltage High Message- Each time
the cluster receives a message from the PCM indicat-
ing the electrical system voltage is greater than 16.6
volts, the check gauges indicator will be illuminated.
The indicator remains illuminated until the cluster
receives a message from the PCM indicating the elec-
trical system voltage is less than 16.1 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 indicator will be
turned on during the bulb check portion of the test to
confirm the functionality of the LED and the cluster
control circuitry.
The PCM continually monitors the engine temper-
ature, oil pressure, and electrical system voltage,
then sends the proper messages to the instrument
cluster. For further diagnosis of the check gauges
indicator or the instrument cluster circuitry that con-
trols the LED, (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING).
For proper diagnosis of the PCM, the CCD data bus,
or the message inputs to the instrument cluster that
control the check gauges indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
CRUISE INDICATOR
DESCRIPTION
A cruise indicator is standard equipment on all
instrument clusters. However, on vehicles notequipped with the optional speed control system, this
indicator is electronically disabled. The cruise indica-
tor consists of the word ªCRUISEº, which appears in
the lower portion of the odometer/trip odometer Vac-
uum-Fluorescent Display (VFD). The VFD is part of
the cluster electronic circuit board, and is visible
through a cutout located in the lower left corner of
the cluster overlay. The dark lens of the VFD pre-
vents the indicator from being clearly visible when it
is not illuminated. The word ªCRUISEº appears in
an amber color and at the same lighting level as the
odometer/trip odometer information when it is illumi-
nated by the instrument cluster electronic circuit
board. The cruise indicator lamp 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 the cluster
programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Chrysler Collision Detection (CCD)
data bus. The cruise indicator receives battery cur-
rent on the instrument cluster electronic circuit
board through the fused ignition switch output (st-
run) circuit whenever the ignition switch is in the On
or Start positions; therefore, the indicator will always
be off when the ignition switch is in any position
except On or Start. The indicator only illuminates
when it is switched to ground by the instrument clus-
ter circuitry. The instrument cluster will turn on the
cruise indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the cruise indicator is illu-
minated for about two seconds as a bulb test.
²Cruise Lamp-On Message- Each time the
cluster receives a cruise lamp-on message from the
PCM indicating the speed control system has been
turned On, the cruise indicator is illuminated. The
indicator remains illuminated until the cluster
receives a cruise lamp-off message from the PCM 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 cruise indicator will be
turned on during the VFD portion of the test to con-
firm the functionality of the VFD, and again during
the bulb check portion of the test to confirm the func-
tionality of the cluster control circuitry.
The PCM continually monitors the speed control
switches to determine the proper outputs to the
speed control servo. The PCM then sends the proper
cruise indicator lamp-on and lamp-off messages to
8J - 18 INSTRUMENT CLUSTERBR/BE
CHECK GAUGES INDICATOR (Continued)

the instrument cluster. For further diagnosis of the
cruise indicator or the instrument cluster circuitry
that controls the indicator, (Refer to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the speed control
system, the PCM, the CCD data bus, or the message
inputs to the instrument cluster that control the
cruise indicator, a DRBIIItscan tool is required.
Refer to the appropriate diagnostic information.
ENGINE TEMPERATURE
GAUGE
DESCRIPTION
An engine coolant temperature gauge is standard
equipment on all instrument clusters. The engine
coolant temperature gauge is located in the lower left
quadrant of the instrument cluster, below the voltage
gauge. The engine coolant temperature gauge con-
sists of a movable gauge needle or pointer controlled
by the instrument cluster circuitry and a fixed 90
degree scale on the cluster overlay that reads left-to-
right from 54É C (130É F) to 127É C (260É F) for gas-
oline engines, or from 60É C (140É F) to 116É C (240É
F) for diesel engines. An International Control and
Display Symbol icon for ªEngine Coolant Tempera-
tureº is located on the cluster overlay, directly below
the lowest graduation of the gauge scale. The engine
coolant temperature gauge graphics are white
against a black field except for a single red gradua-
tion at the high end of the gauge scale, making them
clearly visible within the instrument cluster in day-
light. When illuminated from behind by the panel
lamps dimmer controlled cluster illumination lighting
with the exterior lamps turned On, the white graph-
ics appear blue-green and the red graphics appear
red. The orange gauge needle is internally illumi-
nated. Gauge illumination is provided by replaceable
incandescent bulb and bulb holder units located on
the instrument cluster electronic circuit board. The
engine coolant temperature gauge is serviced as a
unit with the instrument cluster.
OPERATION
The engine coolant temperature gauge gives an
indication to the vehicle operator of the engine cool-
ant temperature. This gauge is controlled by the
instrument cluster circuit board based upon the clus-
ter programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Chrysler Collision Detection (CCD)
data bus. The engine coolant temperature gauge is
an air core magnetic unit that receives battery cur-
rent on the instrument cluster electronic circuit
board through the fused ignition switch output (st-run) circuit whenever the ignition switch is in the On
or Start positions. The cluster is programmed to
move the gauge needle back to the low end of the
scale after the ignition switch is turned to the Off
position. The instrument cluster circuitry controls
the gauge needle position and provides the following
features:
²Engine Temperature Message- Each time
the cluster receives a message from the PCM indicat-
ing the engine coolant temperature is between the
low end of normal [about 57É C (130É F) for gasoline
engines, or 60É C (140É F) for diesel engines] and the
high end of normal [about 129É C (264É F) for gaso-
line engines, or 116É C (240É F) for diesel engines],
the gauge needle is moved to the actual temperature
position on the gauge scale.
²Engine Temperature Low Message- Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is below
the low end of normal [about 57É C (130É F) for gas-
oline engines, or 60É C (140É F) for diesel engines],
the gauge needle is held at the lowest increment [57É
C (130É F) for gasoline engines, or 60É C (140É F) for
diesel engines] at the far left end of the gauge scale.
The gauge needle remains at the far left end of the
scale until the cluster receives a message from the
PCM indicating that the engine temperature is above
about 57É C (130É F) for gasoline engines, or 60É C
(140É F) for diesel engines, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Engine Temperature High Message- Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is above
about 122É C (253É F) for gasoline engines, or 112É C
(233É F) for diesel engines, the gauge needle is moved
to the appropriate position on the gauge scale, the
check gauges indicator is illuminated, and a single
chime tone is sounded. The check gauges indicator
remains illuminated until the cluster receives a mes-
sage from the PCM indicating that the engine tem-
perature is below about 119É C (246É F) for gasoline
engines, or 109É C (226É F) for diesel engines, or
until the ignition switch is turned to the Off position,
whichever occurs first. The chime tone feature will
only repeat during the same ignition cycle if the
check gauges indicator is cycled off and then on
again by the appropriate engine temperature mes-
sages from the PCM.
²Message Failure- If the cluster fails to receive
an engine temperature message, it will hold the
gauge needle at the last indication until a new mes-
sage is received, 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 gauge needle will be
BR/BEINSTRUMENT CLUSTER 8J - 19
CRUISE INDICATOR (Continued)

swept to several calibration points on the gauge scale
in a prescribed sequence in order to confirm the func-
tionality of the gauge and the cluster control cir-
cuitry.
The PCM continually monitors the engine coolant
temperature sensor to determine the engine operat-
ing temperature. The PCM then sends the proper
engine coolant temperature messages to the instru-
ment cluster. For further diagnosis of the engine cool-
ant temperature gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster turns on
the check gauges indicator due to a high engine tem-
perature gauge reading, it may indicate that the
engine or the engine cooling system requires service.
For proper diagnosis of the engine coolant tempera-
ture sensor, the PCM, the CCD data bus, or the mes-
sage inputs to the instrument cluster that control the
engine coolant temperature gauge, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
FUEL GAUGE
DESCRIPTION
A fuel gauge is standard equipment on all instru-
ment clusters. The fuel gauge is located in the lower
right quadrant of the instrument cluster, below the
oil pressure gauge. The fuel gauge consists of a mov-
able gauge needle or pointer controlled by the instru-
ment cluster circuitry and a fixed 90 degree scale on
the cluster overlay that reads left-to-right from E (or
Empty) to F (or Full). An International Control and
Display Symbol icon for ªFuelº is located on the clus-
ter overlay, directly below the highest graduation of
the gauge scale. The text ªFUEL DOORº and an
arrowhead pointed to the left side of the vehicle is
imprinted on the cluster overlay directly below the
fuel gauge to provide the driver with a reminder as
to the location of the fuel filler access. The fuel gauge
graphics are white against a black field except for a
single red graduation at the low end of the gauge
scale, making them clearly visible within the instru-
ment cluster in daylight. When illuminated from
behind by the panel lamps dimmer controlled cluster
illumination lighting with the exterior lamps turned
On, the white graphics appear blue-green and the
red graphics appear red. The orange gauge needle is
internally illuminated. Gauge illumination is pro-
vided by replaceable incandescent bulb and bulb
holder units located on the instrument cluster elec-
tronic circuit board. The fuel gauge is serviced as a
unit with the instrument cluster.
OPERATION
The fuel gauge gives an indication to the vehicle
operator of the level of fuel in the fuel tank. This
gauge is controlled by the instrument cluster circuit
board based upon the cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Chrysler
Collision Detection (CCD) data bus. The fuel gauge is
an air core magnetic unit that receives battery cur-
rent on the instrument cluster electronic circuit
board through the fused ignition switch output (st-
run) circuit whenever the ignition switch is in the On
or Start positions. The cluster is programmed to
move the gauge needle back to the low end of the
scale after the ignition switch is turned to the Off
position. The instrument cluster circuitry controls
the gauge needle position and provides the following
features:
²Percent Tank Full Message- Each time the
cluster receives a message from the PCM indicating
the percent tank full, the cluster programming
applies an algorithm to calculate the proper gauge
needle position, then moves the gauge needle to the
proper position on the gauge scale. The algorithm is
used to dampen gauge needle movement against the
negative effect that fuel sloshing within the fuel tank
can have on accurate inputs from the fuel tank send-
ing unit to the PCM.
²Less Than 12.5 Percent Tank Full Message-
Each time the cluster receives messages from the
PCM indicating the percent tank full is 12.5 (one-
eighth) or less for 10 consecutive seconds and the
vehicle speed is zero, or for 60 consecutive seconds
and the vehicle speed is greater than zero, the gauge
needle is moved to the proper position on the gauge
scale, the low fuel indicator is illuminated, and a sin-
gle chime tone is sounded. The low fuel indicator
remains illuminated until the cluster receives mes-
sages from the PCM indicating that the percent tank
full is greater than 12.5 (one-eighth) for 10 consecu-
tive seconds and the vehicle speed is zero, or for 60
consecutive seconds and the vehicle speed is greater
than zero, or until the ignition switch is turned to
the Off position, whichever occurs first. The chime
tone feature will only repeat during the same igni-
tion cycle if the low fuel indicator is cycled off and
then on again by the appropriate percent tank full
messages from the PCM.
²Less Than Empty Percent Tank Full Mes-
sage- Each time the cluster receives a message from
the PCM indicating the percent tank full is less than
empty, the gauge needle is moved to the far left (low)
end of the gauge scale and the low fuel indicator is
illuminated immediately. This message would indi-
cate that the fuel tank sender input to the PCM is a
short circuit.
8J - 20 INSTRUMENT CLUSTERBR/BE
ENGINE TEMPERATURE GAUGE (Continued)

MALFUNCTION INDICATOR
LAMP (MIL)
DESCRIPTION
A Malfunction Indicator Lamp (MIL) is standard
equipment on all instrument clusters. The MIL is
located near the lower edge of the instrument cluster
overlay, to the left of center. The MIL consists of a
stencilled cutout of the International Control and
Display Symbol icon for ªEngineº 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
lens 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 a Light Emit-
ting Diode (LED) soldered onto the instrument clus-
ter electronic circuit board. The MIL is serviced as a
unit with the instrument cluster.
OPERATION
The Malfunction Indicator Lamp (MIL) gives an
indication to the vehicle operator when the Power-
train Control Module (PCM) has recorded a Diagnos-
tic Trouble Code (DTC) for an On-Board Diagnostics
II (OBDII) emissions-related circuit or component
malfunction. In addition, on models with a diesel
engine an Engine Control Module (ECM) supple-
ments the PCM, and can also record an OBDII DTC.
The MIL is controlled by a transistor on the instru-
ment cluster circuit board based upon cluster pro-
gramming and electronic messages received by the
cluster from the PCM or ECM over the Chrysler Col-
lision Detection (CCD) data bus. The MIL Light
Emitting Diode (LED) receives battery current on the
instrument cluster electronic circuit board through
the fused ignition switch output (st-run) circuit
whenever the ignition switch is in the On or Start
positions; 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 transis-
tor. The instrument cluster will turn on the MIL for
the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the indicator is illuminated
for about seven seconds as a bulb test.
²PCM Lamp-On Message- Each time the clus-
ter receives a lamp-on message from the PCM or
ECM, the indicator will be illuminated. The indicator
can be flashed on and off, or illuminated solid, as dic-
tated by the PCM/ECM message. For some DTC's, if
a problem does not recur, the PCM or ECM will send
a lamp-off message automatically. Other DTC's mayrequire that a fault be repaired and the PCM or
ECM be reset before a lamp-off message will be sent.
For more information on the PCM, the ECM, and the
DTC set and reset parameters, (Refer to 25 - EMIS-
SIONS CONTROL - OPERATION).
²Communication Error- If the cluster receives
no lamp-on message from the PCM or ECM for
twenty seconds, the MIL is illuminated by the instru-
ment cluster to indicate a loss of bus communication.
The indicator remains controlled and illuminated by
the cluster until a valid lamp-on message is received
from the PCM or ECM.
²Actuator Test- Each time the cluster is put
through the actuator test, the indicator will be
turned on during the bulb check portion of the test to
confirm the functionality of the LED and the cluster
control circuitry.
The PCM/ECM continually monitor the fuel and
emissions system circuits and sensors to decide
whether the system is in good operating condition.
The PCM/ECM then sends the proper lamp-on or
lamp-off messages to the instrument cluster. For fur-
ther diagnosis of the MIL or the instrument cluster
circuitry that controls the LED, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster turns on
the MIL after the bulb test, it may indicate that a
malfunction has occurred and that the fuel and emis-
sions systems may require service. For proper diag-
nosis of the fuel and emissions systems, the PCM,
the ECM, the CCD data bus, or the message inputs
to the instrument cluster that control the MIL, a
DRBIIItscan tool is required. Refer to the appropri-
ate diagnostic information.
ODOMETER
DESCRIPTION
An odometer and trip odometer are standard
equipment in all instrument clusters. The odometer
and trip odometer information are displayed in a
common electronic Vacuum-Fluorescent Display
(VFD), which is visible through a small window cut-
out located in the left lower quadrant of the cluster
overlay. However, the odometer and trip odometer
information are not displayed simultaneously. The
trip odometer reset switch on the instrument cluster
circuit board toggles the display between odometer
and trip odometer modes by depressing the odometer/
trip odometer switch knob that extends through the
lower edge of the cluster lens, just right of the
tachometer. Both the odometer and the trip odometer
information is stored in the instrument cluster mem-
ory.
8J - 24 INSTRUMENT CLUSTERBR/BE

turn on the seatbelt indicator for the following rea-
sons:
²Seatbelt Reminder Function- Each time the
cluster receives a battery current input on the fused
ignition switch output (st-run) circuit, the indicator
will be illuminated as a seatbelt reminder for about
seven seconds, or until the ignition switch is turned
to the Off position, whichever occurs first. This
reminder function will occur regardless of the status
of the seatbelt switch input to the cluster.
²Driver Side Front Seatbelt Not Buckled-
Following the seatbelt reminder function, each time
the cluster receives a ground input on the seat belt
switch sense circuit (seatbelt switch closed - seatbelt
unbuckled) with the ignition switch in the Start or
On positions, the indicator will be illuminated. The
seatbelt indicator remains illuminated until the seat
belt switch sense input to the cluster is an open cir-
cuit (seatbelt switch opened - seatbelt buckled), 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 indicator will be
turned on during the bulb check portion of the test to
confirm the functionality of the LED and the cluster
control circuitry.
The seatbelt switch input to the instrument cluster
circuitry can be diagnosed using conventional diag-
nostic tools and methods. For further diagnosis of the
seatbelt indicator or the instrument cluster circuitry
that controls the LED, (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING).
SERVICE REMINDER
INDICATOR
DESCRIPTION
A Service Reminder Indicator (SRI) is standard
equipment on all instrument clusters. However, on
vehicles not equipped with certain optional heavy
duty emission cycle gasoline engines, this indicator is
electronically disabled. The SRI is located near the
lower edge of the instrument cluster overlay, to the
left of center. The SRI consists of a stencilled cutout
of the words ªMAINT REQDº 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
lens behind the cutout in the opaque layer of the
overlay causes the ªMAINT REQDº text to appear in
amber through the translucent outer layer of the
overlay when the indicator is illuminated from
behind by a Light Emitting Diode (LED) soldered
onto the instrument cluster electronic circuit board.The SRI is serviced as a unit with the instrument
cluster.
OPERATION
The Service Reminder Indicator (SRI) gives an
indication to the vehicle operator when engine emis-
sions maintenance procedures should be performed.
This indicator is controlled by a transistor on the
instrument cluster circuit board based upon the clus-
ter programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Chrysler Collision Detection (CCD)
data bus. The SRI Light Emitting Diode (LED)
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (st-run) circuit whenever the ignition
switch is in the On or Start positions; therefore, the
LED will always be off when the ignition switch is in
any position except On or Start. The LED only illu-
minates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the SRI for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the SRI is illuminated for
about two seconds as a bulb test.
²Service Required Lamp-On Message- Each
time the cluster receives a service required lamp-on
message from the PCM indicating that an emissions
maintenance interval has been reached, the SRI will
be illuminated. The indicator remains illuminated
until the cluster receives a service required lamp-off
message from the PCM, 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 SRI will be turned on
during the bulb check portion of the test to confirm
the functionality of the LED and the cluster control
circuitry.
The PCM continually monitors the vehicle speed
sensor to determine the distance the vehicle has been
driven, then sends the proper messages to the instru-
ment cluster. Once the SRI has been illuminated and
the required emissions maintenance procedures have
been completed, the PCM must be reset using a
DRBIIItscan tool before it will send the proper ser-
vice required lamp-off message to the instrument
cluster. Refer to the appropriate diagnostic informa-
tion. For further diagnosis of the SRI or the instru-
ment cluster circuitry that controls the LED, (Refer
to 8 - ELECTRICAL/INSTRUMENT CLUSTER -
DIAGNOSIS AND TESTING). For proper diagnosis
of the PCM, the CCD data bus, or the message
inputs to the instrument cluster that control the SRI,
a DRBIIItscan tool is required. Refer to the appro-
priate diagnostic information.
8J - 28 INSTRUMENT CLUSTERBR/BE
SEATBELT INDICATOR (Continued)