2001 DODGE RAM sensor

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

The odometer can display values up to 499,999
kilometers (499,999 miles). The odometer latches at
these values, and will not roll over to zero. The trip
odometer can display values up to 999.9 kilometers
(999.9 miles) before it rolls over to zero. The odome-
ter display does not have a decimal point and will
not show values less than a full unit (kilometer or
mile), the trip odometer display does have a decimal
point and will show tenths of a unit (kilometer or
mile). The unit of measure (kilometers or miles) for
the odometer and trip odometer display is not shown
in the VFD. The unit of measure for the instrument
cluster odometer/trip odometer is selected at the time
that it is manufactured, and cannot be changed. Dur-
ing daylight hours (exterior lamps Off) the VFD is
illuminated at full brightness for clear visibility. At
night (exterior lamps are On) the VFD lighting level
is adjusted with the other cluster illumination lamps
using the panel lamps dimmer thumbwheel on the
headlamp switch. However, a ªParadeº mode position
of the panel lamps dimmer thumbwheel allows the
VFD to be illuminated at full brightness while the
exterior lamps are turned On during daylight hours.
The VFD, the trip odometer switch, and the trip
odometer switch button are serviced as a unit with
the instrument cluster.
OPERATION
The odometer and trip odometer give an indication
to the vehicle operator of the distance the vehicle has
traveled. This gauge is controlled by the instrument
cluster circuit board based upon the cluster program-
ming and electronic messages received by the cluster
from the Powertrain Control Module (PCM) over the
Chrysler Collision Detection (CCD) data bus. The
odometer and trip odometer information is displayed
by the instrument cluster Vacuum Fluorescent Dis-
play (VFD), and the VFD will not display odometer
or trip odometer information after the ignition switch
is turned to the Off position. The instrument cluster
circuitry controls the VFD and provides the following
features:
²Odometer/Trip Odometer Display Toggling-
Actuating the trip odometer reset switch momen-
tarily with the ignition switch in the On position will
toggle the VFD between the odometer and trip odom-
eter display. Each time the ignition switch is turned
to the On position the VFD will automatically return
to the mode (odometer or trip odometer) last dis-
played when the ignition switch was turned to the
Off position.
²Trip Odometer Reset- When the trip odome-
ter reset switch is pressed and held for longer than
about two seconds, the trip odometer will be reset to
000.0 kilometers (miles). The VFD must be display-ing the trip odometer information in order for the
trip odometer information to be reset.
²Message Failure- If the cluster fails to receive
a distance message during normal operation, it will
flash the odometer/trip odometer distance informa-
tion on and off repeatedly until a distance message is
received, or until the ignition switch is turned to the
Off position, whichever occurs first. If the cluster
does not receive a distance message within one sec-
ond after the ignition switch is turned to the On posi-
tion, it will display the last distance message stored
in the cluster memory. If the cluster is unable to dis-
play distance information due to an error internal to
the cluster, the VFD display will be blank.
²Actuator Test- Each time the cluster is put
through the actuator test, the VFD will display all of
its characters at once, then step through each char-
acter segment individually during the VFD portion of
the test to confirm the functionality of the VFD and
the cluster control circuitry.
The PCM continually monitors the vehicle speed
sensor, then sends the proper distance messages to
the instrument cluster. For further diagnosis of the
odometer/trip odometer or the instrument cluster cir-
cuitry that controls these functions, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
vehicle speed sensor, the PCM, the CCD data bus, or
the message inputs to the instrument cluster that
control the odometer/trip odometer, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
OIL PRESSURE GAUGE
DESCRIPTION
An oil pressure gauge is standard equipment on all
instrument clusters. The oil pressure gauge is located
in the upper right quadrant of the instrument clus-
ter, above the fuel gauge. The oil pressure 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 either from 0 kPa (0 psi) to 758 kPa (110 psi).
An International Control and Display Symbol icon for
ªEngine Oilº is located on the cluster overlay, directly
below the highest graduation of the gauge scale. The
oil pressure 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 instrument cluster in daylight. When illu-
minated from behind by the panel lamps dimmer
controlled cluster illumination lighting with the exte-
rior lamps turned On, the white graphics appear
blue-green and the red graphics appear red. The
BR/BEINSTRUMENT CLUSTER 8J - 25
ODOMETER (Continued)

orange gauge needle is internally illuminated. Gauge
illumination is provided by replaceable incandescent
bulb and bulb holder units located on the instrument
cluster electronic circuit board. The oil pressure
gauge is serviced as a unit with the instrument clus-
ter.
OPERATION
The oil pressure gauge gives an indication to the
vehicle operator of the engine oil pressure. 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 oil pressure
gauge is an air core magnetic unit that receives bat-
tery current on the instrument cluster electronic cir-
cuit 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 Oil Pressure Message- The instru-
ment cluster circuitry restricts the oil pressure gauge
needle operation in order to provide readings that
are consistent with customer expectations. Each time
the cluster receives a message from the PCM indicat-
ing the engine oil pressure is between about 6.9 kPa
(1 psi) and 137.9 kPa (20 psi) for gasoline engines, or
55 kPa (8 psi) and 58.6 kPa (8.5 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 11 degrees above the low end of normal incre-
ment on the gauge scale. Each time the cluster
receives a message from the PCM indicating the
engine oil pressure is between about 517.1 kPa (75
psi) and 755 kPa (109.5 psi) for gasoline engines, or
551.6 kPa (80 psi) and 755 kPa (109.5 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 7.4 degrees below the high end of normal
increment on the gauge scale. When the cluster
receives messages from the PCM indicating the
engine oil pressure is between about 137.9 kPa (20
psi) and 517.1 kPa (75 psi) for gasoline engines, or
58.6 kPa (8.5 psi) and 551.6 kPa (80 psi) for diesel
engines], the gauge needle is moved to the actual
pressure position on the gauge scale.
²Engine Oil Pressure Low Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is below about 6.9
kPa (1 psi) for gasoline engines, or 55 kPa (8 psi) for
diesel engines, the gauge needle is moved to the 0
kPa (0 psi) graduation at the far left (low) end of the
gauge scale, the check gauges indicator is illumi-nated, and a single chime tone is generated. The
gauge needle remains at the low end of the scale and
the check gauges indicator remains illuminated until
the cluster receives a message from the PCM indicat-
ing that the engine oil pressure is above about 6.9
kPa (1 psi) for gasoline engines, or 55 kPa (8 psi) for
diesel engines, or until the ignition switch is turned
to the Off position, whichever occurs first. The clus-
ter will only turn the check gauges indicator lamp on
in response to an engine oil pressure low message if
the engine speed message is greater than zero.
²Engine Oil Pressure High Message- Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is above about 755
kPa (109.5 psi) for gasoline or diesel engines, the
gauge needle is moved to the 758.4 kPa (110 psi)
graduation at the far right (high) end of the gauge
scale. The gauge needle remains at the high end of
the scale until the cluster receives a message from
the PCM indicating that the engine oil pressure is
below about 755 kPa (109.5 psi) for gasoline or diesel
engines, or until the ignition switch is turned to the
Off position, whichever occurs first.
²Message Failure- If the cluster fails to receive
an engine oil pressure 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
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 oil pres-
sure sensor to determine the engine oil pressure. The
PCM then sends the proper engine oil pressure mes-
sages to the instrument cluster. For further diagnosis
of the oil pressure 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 low oil pressure
gauge reading, it may indicate that the engine or the
engine oiling system requires service. For proper
diagnosis of the engine oil pressure sensor, the PCM,
the CCD data bus, or the message inputs to the
instrument cluster that control the oil pressure
gauge, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
8J - 26 INSTRUMENT CLUSTERBR/BE
OIL PRESSURE GAUGE (Continued)

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)

(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster from the instrument
panel. Check for continuity between the 4WD switch
sense circuit cavities of the instrument panel wire
harness connector (Connector C2) for the instrument
cluster and the engine wire harness connector for the
four-wheel drive switch. There should be continuity.
If OK, replace the faulty instrument cluster. If not
OK, repair the open 4WD switch sense circuit
between the instrument cluster and the four-wheel
drive switch as required.
INDICATOR STAYS ILLUMINATED WITH FOUR-WHEEL DRIVE
MODE NOT SELECTED
(1) Disconnect and isolate the battery negative
cable. Disconnect the engine wire harness connector
for the four-wheel drive switch from the switch con-
nector receptacle. Check for continuity between the
ground circuit terminal and the 4WD switch sense
circuit terminal in the four-wheel drive switch con-
nector receptacle. There should be no continuity. If
OK, repair the shorted 4WD switch sense circuit
between the four-wheel drive switch and the instru-
ment cluster as required. If not OK, replace the
faulty four-wheel drive switch.
SPEEDOMETER
DESCRIPTION
A speedometer is standard equipment on all instru-
ment clusters. The speedometer is located just to the
right of the tachometer near the center of the instru-
ment cluster. The speedometer consists of a movable
gauge needle or pointer controlled by the instrument
cluster circuitry and a fixed 210 degree primary scale
on the gauge dial face that reads left-to-right either
from 0 to 120 mph, or from 0 to 200 km/h, depending
upon the market for which the vehicle is manufac-
tured. Each version also has a secondary inner scale
on the gauge dial face that provides the equivalent
opposite units from the primary scale. Text appearing
on the cluster overlay just below the hub of the
speedometer needle abbreviates the unit of measure
for the primary scale in all upper case letters (i.e.:
MPH or KM/H), followed by the unit of measure for
the secondary scale in all lower case letters (i.e.: mph
or km/h). The speedometer graphics are white (pri-
mary scale) and red (secondary scale) against a black
field, 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, while the
red graphics still appear red. The orange gauge nee-
dle is internally illuminated. Gauge illumination isprovided by replaceable incandescent bulb and bulb
holder units located on the instrument cluster elec-
tronic circuit board. The speedometer is serviced as a
unit with the instrument cluster.
OPERATION
The speedometer gives an indication to the vehicle
operator of the vehicle road speed. This gauge is con-
trolled by 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 speedometer is an air
core magnetic unit that receives battery current on
the instrument cluster electronic circuit board
through the fused ignition switch output (st-run) cir-
cuit 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:
²Message Failure- If the cluster fails to receive
a speedometer message, it will hold the gauge needle
at the last indication for about four seconds, or until
the ignition switch is turned to the Off position,
whichever occurs first. If a new speedometer message
is not received after about four seconds, the gauge
needle will return to the far left (low) end of the
scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
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 vehicle speed
sensor to determine the vehicle road speed, then
sends the proper vehicle speed messages to the
instrument cluster. For further diagnosis of the
speedometer or the instrument cluster circuitry that
controls the gauge, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND TEST-
ING). For proper diagnosis of the vehicle speed
sensor, the PCM, the CCD data bus, or the message
inputs to the instrument cluster that control the
speedometer, a DRBIIItscan tool is required. Refer
to the appropriate diagnostic information.
TACHOMETER
DESCRIPTION
A tachometer is standard equipment on all instru-
ment clusters. The tachometer is located just to the
left of the speedometer near the center of the instru-
8J - 30 INSTRUMENT CLUSTERBR/BE
SHIFT INDICATOR (TRANSFER CASE) (Continued)

ment cluster. The tachometer consists of a movable
gauge needle or pointer controlled by the instrument
cluster circuitry and a fixed 210 degree scale on the
gauge dial face that reads left-to-right either from 0
to 6 for gasoline engines, or from 0 to 4 for diesel
engines. The text ªRPM X 1000º imprinted on the
cluster overlay directly below the hub of the tachom-
eter needle identifies that each number on the
tachometer scale is to be multiplied times 1000 rpm.
The gauge scale of the gasoline engine tachometer is
red lined at 5000 rpm, while the diesel engine
tachometer is red lined at 3375 rpm. The diesel
engine tachometer also includes text that specifies
ªDIESEL FUEL ONLYº located just above the hub of
the tachometer needle. The tachometer graphics are
white and red against a black field, 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, while the red graphics still
appear red. The orange gauge needle is internally
illuminated. Gauge illumination is provided by
replaceable incandescent bulb and bulb holder units
located on the instrument cluster electronic circuit
board. The tachometer is serviced as a unit with the
instrument cluster.
OPERATION
The tachometer gives an indication to the vehicle
operator of the engine speed. This gauge is controlled
by the instrument 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 tachometer is an air core mag-
netic unit that receives battery current on the instru-
ment 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:
²Message Failure- If the cluster fails to receive
an engine speed message, it will hold the gauge nee-
dle at the last indication for about four seconds, or
until the ignition switch is turned to the Off position,
whichever occurs first. If a new engine speed mes-
sage is not received after about four seconds, the
gauge needle will return to the far left (low) end of
the scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the gauge needle will be
swept to several calibration points on the gauge scalein a prescribed sequence in order to confirm the func-
tionality of the gauge and the cluster control cir-
cuitry.
The PCM continually monitors the crankshaft posi-
tion sensor to determine the engine speed, then
sends the proper engine speed messages to the
instrument cluster. For further diagnosis of the
tachometer or the instrument cluster circuitry that
controls the gauge, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND TEST-
ING). For proper diagnosis of the crankshaft position
sensor, the PCM, the CCD data bus, or the message
inputs to the instrument cluster that control the
tachometer, a DRBIIItscan tool is required. Refer to
the appropriate diagnostic information.
TRANSMISSION OVERTEMP
INDICATOR
DESCRIPTION
A transmission over-temperature indicator lamp is
standard equipment on all instrument clusters. How-
ever, on vehicles not equipped with the optional auto-
matic transmission, this indicator is electronically
disabled. The transmission over-temperature indica-
tor is located near the lower edge of the instrument
cluster overlay, to the left of center. The transmission
over-temperature indicator consists of a stencilled
cutout of the words ªTRANS TEMPº 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 ªTRANS TEMPº text to appear in
red through the translucent outer layer of the over-
lay when the indicator is illuminated from behind by
a Light Emitting Diode (LED) soldered onto the
instrument cluster electronic circuit board. The
transmission over-temperature indicator is serviced
as a unit with the instrument cluster.
OPERATION
The transmission over-temperature indicator gives
an indication to the vehicle operator when the trans-
mission fluid temperature is excessive, which may
lead to accelerated transmission component wear or
failure. This indicator is controlled by a transistor on
the instrument 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 transmission over-temperature
indicator Light Emitting Diode (LED) receives bat-
tery current on the instrument cluster electronic cir-
cuit board through the fused ignition switch output
BR/BEINSTRUMENT CLUSTER 8J - 31
TACHOMETER (Continued)

(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 bulb only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the transmission over-temperature indicator
for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the transmission over-tem-
perature indicator is illuminated for about two sec-
onds as a bulb test.
²Trans Over-Temp Lamp-On Message- Each
time the cluster receives a trans over-temp lamp-on
message from the PCM indicating that the transmis-
sion fluid temperature is 135É C (275É F) or higher,
the indicator will be illuminated and a single chime
tone is sounded. The lamp remains illuminated until
the cluster receives a trans over-temp lamp-off mes-
sage from the PCM, 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 transmission over-tempera-
ture indicator is cycled off and then on again by the
appropriate trans over-temp messages from the PCM.
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 transmission
temperature sensor to determine the transmission
operating condition, then sends the proper messages
to the instrument cluster. If the instrument cluster
turns on the transmission over-temperature indicator
due to a high transmission oil temperature condition,
it may indicate that the transmission and/or the
transmission cooling system are being overloaded or
that they require service. For further diagnosis of the
transmission over-temperature indicator or the
instrument cluster circuitry that controls the LED,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). For proper
diagnosis of the transmission temperature sensor, the
PCM, the CCD data bus, or the message inputs to
the instrument cluster that control the transmission
over-temperature indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
TURN SIGNAL INDICATORS
DESCRIPTION
Two turn signal indicators are standard equipment
on all instrument clusters. The turn signal indicatorsare located near the upper edge of the instrument
cluster overlay, between the speedometer and the
tachometer. Each turn signal indicator consists of a
stenciled cutout of the International Control and Dis-
play Symbol icon for ªTurn Warningº in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents these icons from
being clearly visible when their lamps are not illumi-
nated. The icons appear in green through the trans-
lucent outer layer of the overlay when the indicator
is illuminated from behind by a replaceable incandes-
cent bulb and bulb holder unit located on the instru-
ment cluster electronic circuit board. The turn signal
indicators are serviced as a unit with the instrument
cluster.
OPERATION
The turn signal indicators give an indication to the
vehicle operator that the turn signal (left or right
indicator flashing) or hazard warning (both left and
right indicators flashing) have been selected. These
indicators are controlled by two individual hard
wired inputs to the instrument cluster electronic cir-
cuit board. The turn signal indicator bulbs are
grounded on the instrument cluster electronic circuit
board at all times. The turn signal indicator bulbs
only illuminate when they are provided with battery
current by the turn signal and hazard warning
switch circuitry of the left multi-function switch on
the steering column through separate left and right
turn signal inputs to the instrument cluster; there-
fore, these indicators can be illuminated, regardless
of the ignition switch position.
The turn signal indicators are connected in series
between ground and the output of the turn signal
and hazard warning switch circuitry, but in parallel
with the other turn signal circuits. This arrangement
allows the turn signal indicators to remain functional
regardless of the condition of the other circuits in the
turn signal and hazard warning system. For more
information on the turn signal and hazard warning
system, (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR - OPERATION - TURN SIGNAL &
HAZARD WARNING SYSTEM). The turn signal
indicators can be diagnosed using conventional diag-
nostic tools and methods.
DIAGNOSIS AND TESTING - TURN SIGNAL
INDICATORS
The diagnosis found here addresses an inoperative
turn signal indicator lamp condition. If the problem
being diagnosed is related to inoperative turn signals
or hazard warning lamps, be certain to repair the
turn signal and hazard warning system before
attempting to diagnose or repair the turn signal indi-
cators. If no turn signal or hazard warning system
8J - 32 INSTRUMENT CLUSTERBR/BE
TRANSMISSION OVERTEMP INDICATOR (Continued)