Engine temperature sensor DODGE RAM 1500 1998 2.G Owner's Manual

TRANSMISSION CONTROL
MODULE
DESCRIPTION
The Transmission Control Module (TCM) (Fig. 9)
may be sub-module within the Powertrain Control
Module (PCM), Engine Control Module (ECM - Diesel
only) (Fig. 10), or a standalone module, depending on
the vehicle engine. The PCM, and TCM when
equipped, is located at the right rear of the engine
compartment, near the right inner fender.
OPERATION
The Transmission Control Module (TCM) controls
all electronic operations of the transmission. The
TCM receives information regarding vehicle opera-
tion from both direct and indirect inputs, and selects
the operational mode of the transmission. Direct
inputs are hardwired to, and used specifically by the
TCM. Indirect inputs are shared with the TCM via
the vehicle communication bus.
Some examples ofdirect inputsto the TCM are:
²Battery (B+) voltage
²Ignition ªONº voltage
²Transmission Control Relay (Switched B+)
²Throttle Position Sensor
²Crankshaft Position Sensor
²Transmission Range Sensor
²Pressure Switches
²Transmission Temperature Sensor
²Input Shaft Speed Sensor
²Output Shaft Speed Sensor
²Line Pressure Sensor
Some examples ofindirect inputsto the TCM
are:²Engine/Body Identification
²Manifold Pressure
²Target Idle
²Torque Reduction Confirmation
²Engine Coolant Temperature
²Ambient/Battery Temperature
²DRBIIItScan Tool Communication
Based on the information received from these var-
ious inputs, the TCM determines the appropriate
shift schedule and shift points, depending on the
present operating conditions and driver demand.
This is possible through the control of various direct
and indirect outputs.
Some examples of TCMdirect outputsare:
²Transmission Control Relay
²Solenoids
²Torque Reduction Request
Some examples of TCMindirect outputsare:
²Transmission Temperature (to PCM)
²PRNDL Position (to BCM)
In addition to monitoring inputs and controlling
outputs, the TCM has other important responsibili-
ties and functions:
²Storing and maintaining Clutch Volume Indexes
(CVI)
²Storing and selecting appropriate Shift Sched-
ules
²System self-diagnostics
Fig. 9 PCM/TCM Location
1 - RIGHT FENDER
2 - TRANSMISSION CONTROL MODULE
3 - POWERTRAIN CONTROL MODULE
Fig. 10 Diesel ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
8E - 20 ELECTRONIC CONTROL MODULESDR

(2) Disconnect and isolate the remote battery neg-
ative cable terminal.
(3) Remove the battery from the vehicle. Refer to
the procedure in this group.
(4) One at a time, trace the battery cable retaining
pushpins, fasteners and routing clips until the cable
is free from the vehicle.
(5) Remove the battery cable from the engine com-
partment.
INSTALLATION
(1) Position the battery cable in the engine com-
partment.
(2) One at a time, install the battery cable retain-
ing pushpins, fasteners and routing clips until the
cable is installed exactly where it was in the vehicle.
Refer to Wiring for illustrations.
(3) Install the battery in the vehicle. Refer to the
procedure in this group.
(4) Connect the battery negative cable terminal.
BATTERY TRAY
DESCRIPTION
The molded plastic tray battery tray is located in
the left front corner of the engine compartment. On
this model, the battery tray also provides an anchor
point for the anti-lock brake controller, cruise control
servo (if equipped) and the integrated power module
(Fig. 15). The battery hold down hardware is con-
tained within the battery tray. A hole in the bottom
of the battery tray is fitted with a battery tempera-
ture sensor. Refer to Charging System for more infor-
mation on the battery temperature sensor.
OPERATION
The battery tray and the battery hold down hard-
ware combine to secure and stabilize the battery in
the engine compartment, which prevents battery
movement during even the most extreme vehicle
operation. Unrestrained battery movement during
vehicle operation could result in damage to the vehi-
cle, the battery, or both.
REMOVAL
LEFT SIDE
(1) Remove the battery from the battery tray
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - REMOVAL).
(2) Remove the integrated power module (Refer to
8 - ELECTRICAL/POWER DISTRIBUTION/INTEL-
LIGENT POWER MODULE - REMOVAL).
(3) Disconnect the wire harness retainers from the
battery tray assembly.
(4) Remove the anti-lock brake controller (if
equipped) retaining bolts and support the brake con-
troller with mechanics wire. It is not necessary to
completely remove the anti-lock brake control unit.
(5) Remove the left front wheelhouse splash shiel-
d(Refer to 23 - BODY/EXTERIOR/LF WHEEL-
HOUSE SPLASH SHIELD - REMOVAL).
(6) Mark the location of the cruise servo (if
equipped) and remove the retaining screws. Position
the servo out of the way.
(7) Remove the battery temperature sensor from
the battery tray (Refer to 8 - ELECTRICAL/CHARG-
ING/BATTERY TEMPERATURE SENSOR -
REMOVAL).
(8) Disconnect the purge solenoid from its mount-
ing bracket.
(9) Disconnect the left front fender ground wire.
(10) Remove the remaining battery tray retaining
bolts (Fig. 16).
(11) Remove the battery tray from the vehicle.
RIGHT SIDE
(1) Remove the battery from the battery tray
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - REMOVAL).
Fig. 15 DR Battery Tray
1 - BATTERY TRAY ASSEMBLY
2 - BATTERY TEMPERATURE SENSOR
3 - ANTI-LOCK BRAKE CONTROLLER MOUNTING LOCATION
4 - INTEGRATED POWER MODULE MOUNTING SANCTION
DRBATTERY SYSTEM 8F - 17
BATTERY CABLES (Continued)

CHARGING
TABLE OF CONTENTS
page page
CHARGING
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - CHARGING
SYSTEM............................19
SPECIFICATIONS
GENERATOR RATINGS.................20
SPECIFICATIONS - TORQUE - GENERATOR
/ CHARGING SYSTEM..................20
BATTERY TEMPERATURE SENSOR
DESCRIPTION.........................21OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................21
GENERATOR
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................22
INSTALLATION.........................24
VOLTAGE REGULATOR
DESCRIPTION.........................25
OPERATION...........................25
CHARGING
DESCRIPTION
The charging system consists of:
²Generator
²Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM). Elec-
tronic Control Module (ECM) for diesel engines.
²Ignition switch
²Battery (refer to 8, Battery for information)
²Battery temperature sensor
²Check Gauges Lamp (if equipped)
²Voltmeter (refer to 8, Instrument Panel and
Gauges for information)
²Wiring harness and connections (refer to 8, Wir-
ing Diagrams for information)
OPERATION
The charging system is turned on and off with the
ignition switch. The system is on when the engine is
running and the ASD relay is energized. When the
ASD relay is on, voltage is supplied to the ASD relay
sense circuit at the PCM (ECM Diesel). This voltage
is connected through the PCM (ECM Diesel) and sup-
plied to one of the generator field terminals (Gen.
Source +) at the back of the generator.
The amount of direct current produced by the gen-
erator is controlled by the EVR (field control) cir-
cuitry contained within the PCM (ECM Diesel). This
circuitry is connected in series with the second rotor
field terminal and ground.
A battery temperature sensor, located in the bat-
tery tray housing, is used to sense battery tempera-
ture. This temperature data, along with data from
monitored line voltage, is used by the PCM (ECM
Diesel) to vary the battery charging rate. This isdone by cycling the ground path to control the
strength of the rotor magnetic field. The PCM then
compensates and regulates generator current output
accordingly.
All vehicles are equipped with On-Board Diagnos-
tics (OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM
(ECM Diesel). Each monitored circuit is assigned a
Diagnostic Trouble Code (DTC). The PCM will store a
DTC in electronic memory for certain failures it
detects.
The Check Gauges Lamp (if equipped) monitors:
charging system voltage,engine coolant tempera-
ture and engine oil pressure. If an extreme condition
is indicated, the lamp will be illuminated. This is
done as reminder to check the three gauges. The sig-
nal to activate the lamp is sent via the CCD bus cir-
cuits. The lamp is located on the instrument panel.
Refer to 8, Instrument Panel and Gauges for addi-
tional information.
DIAGNOSIS AND TESTING - CHARGING
SYSTEM
The following procedures may be used to diagnose
the charging system if:
²the check gauges lamp (if equipped) is illumi-
nated with the engine running
²the voltmeter (if equipped) does not register
properly
²an undercharged or overcharged battery condi-
tion occurs.
Remember that an undercharged battery is often
caused by:
²accessories being left on with the engine not
running
DRCHARGING 8F - 19

DESCRIPTION N´m Ft. Lbs. In. Lbs.
Generator (short)
Horizontal Mounting Bolt -
3.7L / 4.7L Engines74 55 -
Generator B+ Output
Cable Terminal Nut12 - 108
BATTERY TEMPERATURE
SENSOR
DESCRIPTION
The Battery Temperature Sensor (BTS) is attached
to the battery tray located under the battery.
OPERATION
The BTS is used to determine the battery temper-
ature and control battery charging rate. This temper-
ature data, along with data from monitored line
voltage, is used by the PCM (ECM Diesel) to vary the
battery charging rate. System voltage will be higher
at colder temperatures and is gradually reduced at
warmer temperatures.
The PCM sends 5 volts to the sensor and is
grounded through the sensor return line. As temper-
ature increases, resistance in the sensor decreases
and the detection voltage at the PCM increases.
The BTS is also used for OBD II diagnostics. Cer-
tain faults and OBD II monitors are either enabled
or disabled, depending upon BTS input (for example,
disable purge and enable Leak Detection Pump
(LDP) and O2 sensor heater tests). Most OBD II
monitors are disabled below 20ÉF.
REMOVAL
The battery temperature sensor is located under
the vehicle battery and is attached (snapped into) a
mounting hole on battery tray (Fig. 1).
(1) Remove battery. Refer to 8, Battery for proce-
dures.
(2) Pry sensor straight up from battery tray
mounting hole to gain access to electrical connector
(Fig. 1).
(3) Disconnect sensor from engine wire harness
electrical connector.
INSTALLATION
The battery temperature sensor is located under
the vehicle battery and is attached (snapped into) a
mounting hole on battery tray.
(1) Pull electrical connector up through mounting
hole in top of battery tray.
(2) Connect sensor.
(3) Snap sensor into battery tray.(4) Install battery. Refer to 8, Battery for proce-
dures.
GENERATOR
DESCRIPTION
The generator is belt-driven by the engine using a
serpentine type drive belt. It is serviced only as a
complete assembly. If the generator fails for any rea-
son, the entire assembly must be replaced.
OPERATION
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a cur-
rent into the windings of the stator coil. Once the
generator begins producing sufficient current, it also
provides the current needed to energize the rotor.
Fig. 1 BATTERY TEMPERATURE SENSOR
LOCATION
1 - BATTERY TEMP. SENSOR
2 - BATTERY
3 - SENSOR ELEC. CONNECT.
4 - BATTERY TRAY
DRCHARGING 8F - 21
CHARGING (Continued)

(6) Install both negative battery cables to both bat-
teries.
VOLTAGE REGULATOR
DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulat-
ing circuit located within the PCM (Powertrain Con-
trol Module) (within the ECM for diesel engines). The
EVR is not serviced separately. If replacement is nec-
essary, the PCM must be replaced.
OPERATION
The amount of direct current produced by the gen-
erator is controlled by EVR circuitry contained
within the PCM. This circuitry is connected in series
with the generators second rotor field terminal and
its ground.Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
EVR circuitry monitors system line voltage (B+) and
battery temperature (refer to Battery Temperature
Sensor for more information). It then determines a
target charging voltage. If sensed battery voltage is
0.5 volts or lower than the target voltage, the PCM
grounds the field winding until sensed battery volt-
age is 0.5 volts above target voltage. A circuit in the
PCM cycles the ground side of the generator field up
to 100 times per second (100Hz), but has the capabil-
ity to ground the field control wire 100% of the time
(full field) to achieve the target voltage. If the charg-
ing rate cannot be monitored (limp-in), a duty cycle
of 25% is used by the PCM in order to have some
generator output. Also refer to Charging System
Operation for additional information.
DRCHARGING 8F - 25
GENERATOR (Continued)

OPERATION
The heated seat module receives fused battery cur-
rent through the Integrated Power Module. The
heated seat switches receive battery current from the
Cab Compartment Node (CCN) only when the igni-
tion switch is in the On position and the engine is
running. The heated seat module shares a common
ground circuit with each of the heated seat elements.
The heated seat system will control the surface tem-
perature of the seat cushion to within the designed
temperature set points of the system.
The heated seat system will also automatically
turn off whenever the ignition switch is turned to
any position except On, or if the engine quits run-
ning. If the ignition switch is turned to the Off posi-
tion or if the engine quits running while a heated
seat is ON, the heated seat will remain Off after the
engine is restarted until a heated seat switch is
depressed again. This helps prevent the vehicles bat-
tery from being drained by the heated seat system.
The heated seat module monitors inputs from the
heated seat sensors and the heated seat switches. Inresponse to these inputs the heated seat module uses
its internal programming to control 12v to the heated
seat elements in both front seats and to control the
heated seat LED indicator lamps located in both of
the heated seat switches. The heated seat module is
also programmed to provide self-diagnostics, if a
problem with the heated seat system is detected. If
the module detects certain failures within the heated
seat system, it will provide a visual indication of the
failure by flashing the indicator lamps in the appro-
priate heated seat switch. The heated seat module
will automatically turn off the heated seat elements
if it detects a short or open in the heated seat ele-
ment circuit or a heated seat sensor value that is out
of range.
DIAGNOSIS AND TESTING - HEATED SEAT
SYSTEM
HEATED SEAT SYSTEM SELF-DIAGNOSIS
The heated seat system is capable of performing
some self-diagnostics. The following table depicts the
various monitored failures which will be reported to
the vehicle operator or technician by flashing the
individual heated seat switch Light Emitting Diode
(LED) indicator lamps. Refer to the HEATED SEAT
SYSTEM SELF-DIAGNOSIS table for failure identi-
fication. The drivers heated seat switch indicator
lamps will flash if a failure occurs in the driver
heated seat, and the passengers heated seat switch
indicator lamps will flash for a passenger heated seat
failure. If a monitored heated seat system failure
occurs, the switch indicator lamps will flash at a
pulse rate of about one-half second on, followed by
about one-half second off for a duration of about one
minute after the switch for the faulty heated seat is
depressed in either the Low or High direction. This
process will repeat every time the faulty heated seat
switch is actuated until the problem has been cor-
rected.
HEATED SEAT SYSTEM SELF-DIAGNOSIS
Monitored FailureSwitch High
Indicator LampSwitch Low
Indicator Lamp
Heated Seat
Element ShortedFlashing Flashing
Heated Seat
Element OpenFlashing Off
Heated Seat
Sensor Value Out
of RangeOff Flashing
Diagnostic logic is built into the heated seat mod-
ule to help the person trying to locate the problem by
the most efficient means possible. Anytime a problem
Fig. 1 DR Heated Seat System Diagram
1 - WIRE HARNESS
2 - DRIVER HEATED SEAT SWITCH
3 - PASSENGER HEATED SEAT SWITCH
4 - PASSENGER HEATED SEAT CUSHION ELEMENT
5 - SEAT CUSHION/BACK ELEMENT ELECTRICAL CONNECTOR
LOCATION
6 - DRIVER HEATED SEAT BACK ELEMENT
7 - DRIVER HEATED SEAT CUSHION ELEMENT
8 - HEATED SEAT MODULE
8G - 8 HEATED SEAT SYSTEMDR
HEATED SEAT SYSTEM (Continued)

Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 4.7L V-8 engine.
5.7L V-8
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
A ªwasted sparkº system is used on the 5.7L
engine combining paired, or dual-firing coils, and 2
spark plugs per cylinder. The coils and spark plugs
are connected with paired, secondary high-voltage
cables.
Each cylinder is equipped with 1 dual-output coil.
Meaning one coil mounts directly over one of the
dual spark plugs for 1 high-voltage output. A second
high-voltage output is supplied directly from the
same coil (using a plug cable) to one of the dual
spark plugs on a corresponding (paired) cylinder on
the opposite cylinder bank.
Each coil fires 2 spark plugs simultaneously on
each of the cylinder banks (one cylinder on compres-
sion stroke and one cylinder on exhaust stroke).
EXAMPLE :When the #1 cylinder is on compression
stroke and ready for spark, the #1 coil will fire one of
the dual spark plugs on the #1 cylinder (directly
below the coil). The other dual spark plug on the #1
cylinder will be fired by the #6 coil. At the same
time, the #1 coil will fire a ªwasted sparkº to one of
the dual spark plugs at the #6 cylinder as coil #6 also
fires a ªwasted sparkº to one of the dual spark plugs
at the #6 cylinder.
The firing order is paired at cylinders 1/6, 2/3, 4/7,
5/8. Basic cylinder firing order is 1±8±4±3±6±5±7±2.
Battery voltage is supplied to all of the ignition
coils positive terminals from the ASD relay. If the
PCM does not see a signal from the crankshaft and
camshaft sensors (indicating the ignition key is ON
but the engine is not running), it will shut down the
ASD circuit.
Base ignition timing is not adjustable on the
5.7L V-8 engine.By controlling the coil ground cir-
cuits, the PCM is able to set the base timing and
adjust the ignition timing advance. This is done to
meet changing engine operating conditions.
The PCM adjusts ignition timing based on inputs it
receives from:
²The engine coolant temperature sensor
²The crankshaft position sensor (engine speed)²The camshaft position sensor (crankshaft posi-
tion)
²The manifold absolute pressure (MAP) sensor
²The throttle position sensor
²Transmission gear selection
REMOVAL
3.7L V-6
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 16). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connec-
tor and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 16).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
4.7L V-8
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 17). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector (Fig. 17) from
coil by pushing downward on release lock on top of
connector and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
DRIGNITION CONTROL 8I - 13
IGNITION COIL (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)

²Actuator Test- Each time the cluster is put
through the actuator test, the engine coolant temper-
ature gauge needle will be swept to several calibra-
tion points on the gauge scale in a prescribed
sequence in order to confirm the functionality of the
gauge and the cluster control circuitry.
On vehicles with a gasoline engine, the PCM con-
tinually monitors the engine coolant temperature
sensor to determine the engine operating tempera-
ture. On vehicles with a diesel engine, the ECM con-
tinually monitors the engine coolant temperature
sensor to determine the engine operating tempera-
ture. The PCM or ECM then sends the proper engine
coolant temperature messages to the instrument
cluster. For further diagnosis of the engine coolant
temperature gauge or the instrument cluster cir-
cuitry 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 ECM, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the engine coolant temperature
gauge, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
ETC INDICATOR
DESCRIPTION
An Electronic Throttle Control (ETC) indicator is
standard equipment on all gasoline engine instru-
ment clusters (Fig. 16). However, on vehicles not
equipped with the optional 5.7 liter gasoline engine,
this indicator is electronically disabled. The ETC
indicator is located on the right side of the instru-
ment cluster, to the right of the engine temperature
gauge. The ETC indicator consists of a stencil-like
cutout of the International Control and Display Sym-
bol icon for ªElectronic Throttle Controlº 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 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 theinstrument cluster electronic circuit board. The ETC
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The Electronic Throttle Control (ETC) indicator
gives an indication to the vehicle operator when the
ETC system is faulty or inoperative. The ETC indi-
cator is controlled by a transistor on the instrument
cluster circuit board based upon cluster programming
and electronic messages received by the cluster from
the Powertrain Control Module (PCM) over the Pro-
grammable Communications Interface (PCI) data
bus. The ETC indicator Light Emitting Diode (LED)
is completely controlled by the instrument cluster
logic circuit, and that logic will only allow this indi-
cator 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 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 ETC indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the ETC indicator is illu-
minated for about six seconds. The entire six second
bulb test is a function of the PCM.
²ETC Lamp-On Message- Each time the clus-
ter receives a lamp-on message from the PCM, the
ETC indicator will be illuminated. The indicator can
be flashed on and off, or illuminated solid, as dic-
tated by the PCM message. The indicator remains
illuminated solid or continues to flash for about
twelve seconds or until the cluster receives a lamp-off
message from the PCM, whichever is longer. If the
indicator is illuminated solid with the engine run-
ning the vehicle will usually remain drivable. If the
indicator is flashing with the engine running the
vehicle may require towing. A flashing indicator
means the ETC system requires immediate service.
²Communication Error- If the cluster receives
no ETC lamp messages for three consecutive seconds,
the ETC indicator is illuminated. The indicator
remains illuminated until the cluster receives a sin-
gle lamp-off message from the PCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the ETC 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 ETC indicator is a function of
the PCM.
The PCM continually monitors the ETC system cir-
cuits and sensors to decide whether the system is in
good operating condition. The PCM then sends the
Fig. 16 ETC Indicator
DRINSTRUMENT CLUSTER 8J - 25
ENGINE TEMPERATURE GAUGE (Continued)

the trip odometer reset switch button is pressed in
order to toggle to the engine hours display. The
engine hours will remain displayed for about thirty
seconds, until the engine speed message is greater
than zero, or until the ignition switch is turned to
the Off position, whichever occurs first.
²Trip Odometer Reset- When the trip odome-
ter reset switch button is pressed and held for longer
than about two seconds with the ignition switch in
the On or Start positions, the trip odometer will be
reset to 0.0 kilometers (miles). The VFD must be dis-
playing the trip odometer information in order for
the trip odometer information to be reset.
²Communication Error- If the cluster fails to
receive a distance message during normal operation,
it will hold and display the last data received until
the ignition switch is turned to the Off position. If
the cluster does not receive a distance message
within one second after the ignition switch is turned
to the On position, it will display the last distance
message stored in the cluster memory. If the cluster
is unable to display distance information due to an
error internal to the cluster, the VFD display will be
dashes.
²Actuator Test- Each time the cluster is put
through the actuator test, the odometer VFD will dis-
play all of its segments simultaneously during the
VFD portion of the test to confirm the functionality
of each of the VFD segments and the cluster control
circuitry.
The PCM continually monitors the vehicle speed
pulse information received from the vehicle speed
sensor and engine speed pulse information received
from the crankshaft position sensor, then sends the
proper distance and engine speed 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 crankshaft position sensor,
the PCM, the PCI data bus, or the electronic message
inputs to the instrument cluster that control the
odometer/trip odometer, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
OIL PRESSURE GAUGE
DESCRIPTION
An oil pressure gauge is standard equipment on all
instrument clusters. The oil pressure gauge is locatedin the upper right quadrant of the instrument clus-
ter, above the coolant temperature gauge. The oil
pressure gauge consists 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 ªLº (or Low) to ªHº (or
High) for gasoline engines. On vehicles with a diesel
engine the scale reads from ª0º kPa to ª760º kPa in
markets where a metric instrument cluster is speci-
fied, or from ª0º psi to ª110º psi in all other markets.
An International Control and Display Symbol icon for
ªEngine Oilº is located on the cluster overlay, directly
below the left end of the gauge scale (Fig. 24). The oil
pressure gauge graphics are black against a white
field except for two red graduations at the low end of
the gauge scale, making them clearly visible within
the instrument cluster in daylight. When illuminated
from behind by the panel lamps dimmer controlled
cluster illumination lighting with the exterior lamps
turned On, the black graphics appear blue and the
red graphics still appear red. The orange gauge nee-
dle is internally illuminated. Gauge illumination is
provided by replaceable incandescent bulb and bulb
holder units located on the instrument cluster elec-
tronic circuit board. The oil pressure gauge is ser-
viced as a unit with the instrument cluster.
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 cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) on vehicles with a
gasoline engine, or from the Engine Control Module
(ECM) on vehicles equipped with a diesel engine over
the Programmable Communications Interface (PCI)
data bus. The oil pressure gauge 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 (run-start) circuit when-
ever the ignition switch is in the On or Start posi-
tions. The cluster is programmed to move the gauge
needle back to the low end of the scale after the igni-
tion switch is turned to the Off position. The instru-
ment 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 or ECM
indicating the engine oil pressure is above about 41
kPa (6 psi) the cluster holds the gauge needle at a
point near the middle increment within the normal
range on the gauge scale.
Fig. 24 Engine Oil Icon
DRINSTRUMENT CLUSTER 8J - 33
ODOMETER (Continued)