oil temperature DODGE TRUCK 1993 Service Owner's Guide

8D
- 16
IGNITION
SYSTEMS

• other operating conditions are causing engine over­
heating. (The heat range rating refers to the operat­
ing temperature of a particular type spark plug.
Spark plugs are designed to operate within specific
temperature ranges. This depends upon the thickness and length of the center electrodes porcelain insula­
tor.)

GROUND

ELECTRODE
CENTER

ELECTRODE

DISSOLVED

J908D-14 Fig. 26 Preignition Damage

SPARK
PLUG
OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
27).
The increase in electrode gap will be consider­
ably in excess of 0.001 inch per 1000 miles of opera­
tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions can also cause spark plug overheating.

BLISTERED

WHITE
OR
J908D-16
Fig. 27 Spark Plug Overheating

SPARK
PLUG
SECONDARY
CABLES
Spark plug heat shields are pressed into the cylin­
der head to surround each spark plug cable boot and spark plug (Fig. 28). These shields protect the spark
plug boots from damage (due to intense engine heat
generated by the exhaust manifolds) and should not be removed. After the spark plug cable has been in­
stalled, the lip of the cable boot should have a small
air gap to the top of the heat shield (Fig. 28).

Fig.
28 Heat
Shields
TESTING

Spark plug cables are sometimes referred to as sec­
ondary ignition cables or secondary wires. The cables
transfer electrical current from the distributor to in­ dividual spark plugs at each cylinder. The spark plug
cables are of nonmetallic construction and have a
built in resistance. The cables provide suppression of radio frequency emissions from the ignition system.
Check the high-tension cable connections for good
contact at the ignition coil, distributor cap towers and spark plugs. Terminals should be fully seated.
The terminals and spark plug covers should be in good condition. Terminals should fit tightly to the ig­
nition coil, distributor cap and spark plugs. The spark plug cover (boot) of the cable should fit tight
around the spark plug insulator. Loose cable connec­
tions can cause corrosion and increase resistance, re­ sulting in shorter cable service life. Clean the high tension cables with a cloth moist­
ened with a nonflammable solvent and wipe dry.
Check for brittle or cracked insulation. When testing secondary cables for damage with an
oscilloscope, follow the instructions of the equipment
manufacturer. If an oscilloscope is not available, spark plug cables
may be tested as follows:

CAUTION:
Do not leave any one
spark
plug
cable

disconnected
for
longer
than
necessary
during test­
ing.
This
may
cause
possible
heat
damage
to the
catalytic converter. Total test
time
must
not exceed
ten
minutes.

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

8D
- 18
IGNITION
SYSTEMS

•
COMPONENT REMGWAL/INSTALLATION

INDEX

page

Automatic
Shut Down (ASD) Relay
18
Camshaft
Position
Sensor
, 18

Crankshaft Position
Sensor
18
Distributor
Service
20
Engine
Coolant Temperature
Sensor
20

General
Information
18
Ignition
Coil
21
page

Intake
Manifold Charge
Air
Temperature
Sensor
. 22

Manifold Absolute Pressure (MAP)
Sensor
..... 22

Oxygen
(02)
Sensor
22
Powertrain
Control
Module (PCM)
22

Spark
Plug Secondary Cables
24

Spark
Plugs
23

Throttle
Position
Sensor
(TPS)
24

GENERAL
INFORMATION
This section
of the
group, Component Removal/In­
stallation, will discuss
the
removal
and
installation
of ignition system components. For basic ignition system diagnostics
and
service
adjustments, refer
to the
Diagnostics/Service Proce­
dures section
of
this group. For system operation
and
component identification,
refer
to the
Component Identification/System Opera­
tion section
of
this group.

AUTOMATIC
SHUT DOWN
(ASb)
RELAY
The automatic shut down
(ASD)
relay
is
located
in

the engine compartment
(Fig. 1).
TORQUE CONVERTER
CLUTCH RELAY
A/C
CLUTCH RELAY STARTER RELAY

AUTO
SHUTDOWN RELAY FUEL PUMP RELAY DATA UNK
CONNECTOR POWERTRAIN
CONTROL
MODULE
J9314-164

Fig.
1
Auto
Shut Down
Relay
REMOVAL

(1) Disconnect negative battery cable
at
battery.

(2)
Remove
the
relay
by
pulling from connector.

INSTALLATION
(1) Check
the
terminals
in the
relay connector
for

corrosion
or
damage before installation.

(2)
Push
the
relay into
the
connector.

CAMSHAFT POSITION SENSOR
The camshaft position sensor
is
located
in the
dis­
tributor
(Fig. 2).
REMOVAL

Distributor removal
is not
necessary
to
remove
camshaft position sensor.

CAMSHAFT POSITION
SENSOR
SYNC

SIGNAL

GENERATOR
DISTRIBUTOR
ASSEMBLY
J9314-82

Fig.
2
Camshaft Position Sensor—Typical
(1) Disconnect negative battery cable
at
battery.

(2)
Remove distributor
cap
from distributor
(two

screws).
(3) Disconnect camshaft position sensor wiring
harness from main engine wiring harness.
(4) Remove distributor rotor from distributor shaft.

(5)
Lift
the
camshaft position sensor assembly from
the distributor housing
(Fig. 2).

INSTALLATION
(1) Install camshaft position sensor
to
distributor.
Align sensor into notch
on
distributor housing.
(2)
Connect wiring harness.
(3) Install rotor.
(4) Install distributor
cap.
Tighten mounting
screws.

CRANKSHAFT
POSITION SENSOR
REMOVAL The sensor
is
bolted
to the top of the
cylinder block
near
the
rear
of
right cylinder head
(Fig. 3).

8D
- 22
IGNITION
SYSTEMS

• (1) Disconnect the wiring and secondary cable from
the ignition coil (Figs. 9 or 10).

WARNING:
(3.9L/5.2L/5.9L
LDC-GAS ENGINES)
DO
NOT REMOVE
THE
COIL MOUNTING BRACKET-TO-
CYLINDER HEAD MOUNTING BOLTS.
THE
COIL MOUNTING BRACKET
IS
UNDER ACCESSORY
DRIVE BELT TENSION.
IF
THIS BRACKET
IS TO BE
REMOVED
FOR ANY
REASON,
ALL
BELT TENSION
MUST FIRST
BE
RELIEVED. REFER
TO THE
BELT
SECTION
OF
GROUP
7,
COOLING SYSTEM.

(2) Remove ignition coil from coil mounting
bracket (two bolts).
INSTALLATION (1) Install the ignition coil to coil bracket. If nuts
and bolts are used to secure coil to coil bracket,
tighten to 11 N«m (100 in. lbs.) torque. If the coil mounting bracket has been tapped for coil mounting

bolts,
tighten bolts to 5 N«m (50 in. lbs.) torque.
(2) Connect all wiring to ignition coil.

INTAKE MANIFOLD CHARGE
AIR
TEMPERATURE

SENSOR

REMOVAL The charge air temperature sensor is located in
right-front side of intake manifold (Figs. 11 or 12).
Fig.
11
Sensor
Location—3.9L Engine—Typical
(1) Disconnect electrical connector at sensor (Figs.
11 or 12).
(2) Remove sensor from intake manifold.
INSTALLATION (1) Install sensor to intake manifold. (2) Tighten the sensor to 13 N-m (10 ft. lbs.)
torque. (3) Install electrical connector.
Fig.
12
Sensor
Location—5.2L/5.9L

Engines—Typical
MANIFOLD ABSOLUTE
PRESSURE
(MAP)
SENSOR

For removal and installation, refer to Manifold Ab­
solute Pressure Sensor in group 14, Fuel Systems.

OXYGEN
(02)
SENSOR
For diagnostics and removal/installation proce­

dures,
refer to Group 14, Fuel Systems, in this man­

ual.
POWERTRAIN CONTROL MODULE
(PCM)
REMOVAL The PCM is located in the engine compartment be­
hind the battery and under the left front fender (Fig.

13).
DATA
UNK CONTROL
CONNECTOR MODULE
J9314-164

Fig.
13 PCM Location—Typical (1) Disconnect negative battery cable at battery.
(2) Disconnect positive battery cable at battery.
(3) Remove battery holddown clamps and remove
battery.
(4) Remove 60-way electrical connector from PCM.
(5) Remove the three PCM mounting bolts (Fig.

14).

• • ^ ^ ^ INSTRUMENT PANEL AND GAUGES 8E - 1
CONTENTS

page
CLUSTER AND GAUGE SERVICE PROCEDURES . 12
CLUSTER AND GAUGE TEST PROCEDURES .. i
GENERAL INFORMATION . 1
page

MESSAGE CENTER-DIESEL ENGINE ........ 4
MESSAGE CENTER-GAS ENGINE .......... 3

SWITCH
AND PANEL COMPONENT SERVICE . 16
GENERAL
INFORMATION
INDEX

page

Generator
Indicating
System
2
Distance
Sensor
2

Electronic
Digital
Clock
3

Fuel
Level
Indicating
System
1
page

Malfunction
Indicator
(Check
Engine)
3

Oil
Pressure
Warning
Lamp
................. 2
Speedometer/Odometer
System
2

Temperature
and Oil
Indicating
System
......... 2
D-body trucks have an instrument cluster which
includes gauges for fuel level, coolant temperature,
oil pressure, and charging system voltage (Fig. 1).
When the ignition switch is in the OFF position all
the gauges will show a reading except the voltage gauge. However, the readings are only accurate
when the ignition switch is in the ON position.
The cluster also includes warning lamps for:
• seat belt warning
• low oil pressure
• high beam
• left and right turn signals
• check engine. J908E-66

Fig.
11nstrument
Cluster
FUEL LEVEL INDICATING SYSTEM (FIG. 2)
A hinged float arm in the fuel tank raises or lowers
depending on the fuel level. The float arm contacts a
variable resistor in the gauge sending unit. This pro­
vides a change of resistance in the fuel gauge circuit
with any up or down movement of the float. This sender
resistance is shown as fuel level on the gauge. Resistance is greatest when the fuel level in the
tank is low and the float arm drops. With high resis­
tance current flow is low and consequently positions
the instrument panel gauge pointer to low.
Resistance in the circuit is at a minimum when the
tank is full and the float arm is raised. With resis­
tance at a minimum, current flow is high registering
full on the instrument panel gauge.
12
VOLTS
TO

GAUGE
IP

FUEL
TANK

SENDING
UNIT

FLOAT

SENDING
UNIT
1:
1
j
^
fCONNECTOR

!g|yj-»—
FUEL

GAUGE

FUEL

TANK

J098E-47

Fig.
2
Fuel
Level
Indicating
System

INSTRUMENT PANEL AND GAUGES

8E
- 2
INSTRUMENT PANEL
AND
GAUGES

•
TEMPERATURE AND
OIL
INDICATING SYSTEM
(FIG.
3) The operation of the temperature and oil pressure
indicating systems are identical. In the temperature
system the sending unit resistance varies in direct
relationship to the temperature of the coolant. When the engine is cold, the resistance of the tem­
perature sending unit is high and a cold temperature
will be indicated on the gauge. When the engine is hot, the resistance of the tem­
perature sending unit is low and a hot temperature
will be indicated on the gauge. In the oil pressure indicating system the sending
unit resistance is actuated by a diaphragm as the oil
pressure increases or decreases. Low oil pressure causes high resistance. High pressure causes low re­
sistance. 12
VOLTS
TO
GAUGE
TEMPERATURE/
OIL GAUGE
TEMPERATURE/OIL SENDING
UNIT
J908E-48
Fig. 3 Temperature/Oil indicating System

OIL
PRESSURE
WARNING LAMP
The oil pressure warning switch, mounted on the
engine, is controlled by engine oil pressure. When engine oil pressure is normal, the switch is
held in the OFF or OPEN position. This stops cur­
rent from flowing to the oil pressure warning lamp
on instrument panel. When the engine oil pressure is low, the switch is
in the ON or CLOSED position. This allows current
to flow to the oil pressure warning lamp in the in­ strument cluster causing the warning lamp to illumi­

nate.
GENERATOR
INDICATING
SYSTEM
(FIG. 4)
The voltmeter gauge senses the voltage of the elec­
trical system.
VOLTAGE
/*

GAUGE
P/
J908E-49 Fig. 4 Generator Indicating System

SPEEDOMETER/ODOMETER SYSTEM
The speedometer/odometer system consists of an
electric speedometer and pushbutton reset odometer
mounted in the cluster. The system also includes the
wire harness from the cluster to the distance sensor at the transmission, and the adapter and pinion in
the transmission. The speedometer/odometer has the same appearance as a conventional version but it
eliminates the cable-driven mechanical system. A signal is sent from a transmission mounted distance
sensor to the speedometer/odometer circuitry through
the wiring harness. By eliminating the speedometer cable, instrument cluster service and removal is im­
proved. Refer to Group 21 - Transmission for select­ ing the proper pinion, and selecting and indexing the
proper adapter.

DISTANCE
SENSOR

DISTANCE SENSOR TEST For testing of the distance sensor and related com­
ponents refer to the Vehicle Diagnostics Test Proce­ dure Manual.
DISTANCE SENSOR REMOVAL AND INSTALLATION (1) Remove harness connector from sensor. Be sure
weather seal stays on harness connector. (2) Remove sensor by loosening sensor coupling
nut from the pinion gear adapter until sensor is free (Fig. 5).
(3) To install the sensor, reverse the removal pro­
cedures. Tighten coupling nut to 17 N»m (150 in. lbs.)

•

INSTRUMENT PANEL
AND
GAUGES
8E - 5
CLUSTER
AND
GAUGE TEST
PROCEDURES

INDEX
page
Fuel Gauge
Circuit
Test
9

Fuel Tank Sending
Unit
Test
5

Oil Pressure Gauge
Circuit
Test
..............
9
Sending
Unit
(Sensor) Test
5
page
Speedometer
10

Temperature
Gauge
Circuit
Test
8
Voltage Gauge
Circuit
Test
10

Warning Lamp System Tests
6

CAUTION:
Disconnect
battery
negative cable,
in
en­

gine compartment, before servicing instrument panel. When power
is
required
for
test purposes,
connect
battery
cable
(for
test only).

Disconnect battery negative cable after test
and before continuing service procedures.

SENDING
UNIT
(SENSOR) TEST
When
a
problem occurs with
a
cluster gauge,
be­

fore disassembling
the
cluster
to
check
the
gauge, check
for a
defective sending unit (sensor)
or
wiring.
(1) Sending units
and
wiring
can be
checked
by

grounding
the
connector leads,
at the
sending unit,
in
the
vehicle.

CAUTION:
When connecting
an
input
terminal
to

ground,
Do Not
leave
the
connection grounded
for
more than
a
few
seconds.

(2) With
the
ignition
in the ON
position;
a

grounded input will cause
the oil,
fuel
or
tempera­
ture gauge
to
read
at or
above maximum.
FUEL TANK SENDING
UNIT
TEST

(1) Disconnect wire from terminal
on
fuel tank
sending unit (Fig.
1).

FUEL PUMP SUPPLY
INPUT
TO
GAUGE
SENDING
UNIT
GROUND
FUEL PUMP GROUND
J928E-49

Fig.
1
Fuel
Tank
Sending
Connector
Terminals
(2) Connect wire
to a
known good sending unit.
(3) Connect
a
jumper wire between sending unit
fuel pick
up
tube
and a
good ground.
(4) Check fuel gauge
as
described
in
following

steps.
Allow
at
least three minutes
at
each test point
for gauge
to
settle. Lightly tapping instrument clus­
ter
may
help position pointer.

FUEL GAUGE SYSTEM DIAGNOSIS
FUEL GAUGE SYSTEM DIAGNOSIS FUEL GAUGE

DOES
NOT

READ
FULL FAULTY PRINTED
CIRCUIT BOARD FUEL GAUGE
INOPERATIVE OR ERRATIC FUEL GAUGE
INACCURATE

E

1

I

CHECK
FAULTY WIRING
OR
TANK DEFORMED
TANK
NOT
FULL COMPONENTS
CHECK
CHECK
ALL WIRING INCLUDING GROUND
i

FAULTY FUEL GAUGE SENDING
UNIT
i 1
FUEL
C
1
DOES
1
READ
1
pAUGE
I

>N0?
1

EMPTY
1

r

TANK
NOT
EMPTY
CHECK
PROPER
ALIGNMENT
OF PICKUP AND

SENDER
ASSEMBLY.

REFER
TO
GROUP
14
FAULTY FUEL
GAUGE

J908E-74

•

INSTRUMENT
PANEL
AND
GAUGES
8E - 7

STEERING PUMP
ENGINE
BLOCK
J9U9-74

Fig.
4 Oil
Pressure
Sending
Unit—Diesel
Engine
COMBINATION
OIL
UNIT
TEST
(FIG. 5)
The combination oil unit has 2 functions:
(1) The normal closed circuit keeps the oil pressure
warning lamp on until there is oil pressure. (2) The sending provides a resistance that varies
with oil pressure.
To test the normally closed oil lamp switch, discon­
nect the locking connector and measure the resis­
tance between the switch terminal and the metal
housing. The ohmmeter should read 0 ohms. Start
the engine.
If there is oil pressure, the ohmmeter should read
an open circuit. To test the sending unit, measure the resistance
between the sending unit terminal and the metal
housing. The ohmmeter should read open, Start the engine.
The ohmmeter should read between 30 to 55 ohms,
depending on engine speed, oil temperature, and oil
viscosity.
If the previous results are not obtained, replace the
switch.

SEAT
BELT
WARNING
SYSTEM
For testing of this system refer to Section 8M -
Seat Belt Warning Systems.

BRAKE
SYSTEM
WARNING
LAMP
(FIG. 6) The brake warning lamp illuminates when the
parking brake is applied with the ignition key
turned ON. The same lamp will also illuminate should one of the two service brake systems fail
when the brake pedal is applied. To test the system
turn the ignition key ON, and apply the parking
brake. If the lamp fails to light, inspect for a burned
out bulb, disconnected socket, a broken or discon-
ENGINE WARNING LAMP DIAGNOSIS
OIL PRESSURE
FUNCTION

TURN

IGNITION

SWITCH
"OH"
(DO NOT
ISTART ENGINE)! LAMP "OFF'
LAMP "ON"
DEFECTIVE BULB START AND IDLE
ENGINE
BULB SOCKET OR WIRING OPEN LAMP STAYS
"ON" TURN OFF
ENGINE LAMP GOES
"OFF" DEFECTIVE
SWITCH CHECK FOR
GROUNDED WIRING
WARNING
LIGHT
OK CHECK FOR
LOW OIL LEVEL
ENGINE OIL
PRISSURi
LOW
REFER TO
ENGINE SERVICE DIAGNOSIS ENGIM

PRES
0
IE OIL
1

SURE
1
,K I

DEFECTIVE SWITCH TEST ENGINE
OIL PRESSURE

PR1448C

SWITCH
(LIGHT)
SENDING
UNIT

(GAUGE)

898E-2

Fig.
5 Combination Oil Unit Terminals
nected wire at the switch. The lamp also lights when
the ignition switch is turned to the START position. To test the service brake warning system,
(1) Raise the vehicle on a hoist.
(2) Open a wheel cylinder bleeder while a helper

INSTRUMENT
PANEL
AND
GAUGES
8E - S
J938E-34
Fig. 7 Coolant Temperature Sensor—Gas Engine
AIR
TEMPERATURE SWITCH

-
COOLANT TEMPERATURE
SWITCH

Fig. 8 Coolant Temperature Sensor—Diesel Engine

OIL PRESSURE
GAUGE
CIRCUIT
TEST
(1) Remove oil pressure gauge. Refer to Gauge Re­
placement. (2) Check for continuity in the wire between the
oil pressure sensor and the oil pressure gauge (sensor
input pin) (Figs. 10, 11, 12 and 13). (3) With the ignition switch in the ON position,
check for battery voltage across the B+ pin and the Ground pin. J908E-6i_
Fig. 9 Temperature Gauge Pins

TEMPERATURE/OIL/FUEL
GAUGE
DIAGNOSIS

GAUGE INDICATES HIGHER

OR
LOWER
THAN
ACTUAL I
FAULTY WIRING
FAULTY SENDING
UNIT*

FAULTY INSTRUMENT PANEL
GAUGE*
ERRATIC
GAUGE OPERATION
'TEST

PROCEDURES

DESCRIBED

ARE
IN
APPROPRIATE
SECTION OF

SERVICE

MANUAL

LOOSE
OR DIRTY ELECTRICAL CONNECTIONS FAULTY INSTRUMENT PANEL
GAUGE*
J908E-52

FUEL
GAUGE
CIRCUIT
TEST
(1) Remove fuel gauge assembly. Refer to Gauge
Replacement. (2) Check for continuity in the wire between the
fuel tank sending unit and the gauge (fuel level in­
put pin) (Figs. 14 and 15). (3) With the ignition switch in the ON position,
check for battery voltage across the B + pin and the Ground pin.

INSTRUMENT PANEL
AND
GAUGES
8E - 13

INSTRUMENT
PANEL MAP LAMP
BRACKET
HEADLAMP
SWITCH

CLUSTER

ASSEMBLY

HEADLAMP

SWITCH
MOUNTING
NUT CARGO LAMP
SWITCH

BEZEL
AND
APPLIQUE

HEADLAMP
KNOB
AND
STEM

BRACKET-AAAP LAMP
MOUNTING

Fig.
2 Instrument
Panel
(6) Position lower steering cover and install 4
screws.

(7)
Install bezel.
(8)
Remove protective cover from steering column.
(9) Connect negative cable to battery. (10) Check to see that all instruments are func­
tioning properly.

PRINTED CIRCUIT BOARD
A visual inspection of the conductors should be
made for cracks or damaged circuits. If no visual
damage is evident, each circuit should be tested for continuity with an ohmmeter or a test light. Should an open circuit be detected, the printed circuit board
should be replaced.
REMOVAL (FIG. 3J (1) Remove instrument cluster. See cluster re­
moval.

(2)
Remove lamp socket assemblies.
(3) Remove gauge mounting screws and remove
gauges.
(4) Remove printed circuit board mounting screws.
(5)
Remove printed circuit board from cluster hous­
ing.
HEADLAMP

SWITCH
BEZEL
CLUSTER MASK AND LENS
J928E-46
Cluster
and
Switches

INSTALLATION

CAUTION:
Do not overtighten mounting
screws
or

damage
to circuit
board
and/or
cluster
housing
will

occur.

(1) Position printed circuit board on cluster hous­
ing, install mounting screws and tighten.
(2)
Install gauges.
(3) Install lamp socket assemblies. Be sure illumi­
nation lamp diffusers are installed. (4) Install instrument cluster.

FUEL GAUGE

TEMPERATURE
GAUGE VOLTAGE GAUGE
OIL
PRESSURE
GAUGE
It is not necessary to remove instrument clus­
ter from vehicle for gauge replacement. When removing gauge assemblies (Fig. 4) from
cluster, gauge must be pulled straight out, not
twisted, or damage to gauge pin and/or printed cir­ cuit board may result. (1) Disconnect negative cable from battery.

(2)
Remove bezel. Refer to Cluster Bezel Removal. (3) Remove cluster mask and lens. Refer to Cluster
Mask and Lens Removal.

8E
- 14
INSTRUMENT
PANEL
AND
GAUGES

•
VOLTAGE
GAUGE
Fig. 3 instrument Cluster Printed Circuit Board

SPEEDOMETER OIL
PRESSURE

GAUGE
TEMPERATURE GAUGE
FUEL
GAUGE

Fig. 4 Cluster With Mask Removed
J908E-69

(4)
Remove gauge mounting screws.
(5) Pull gauge rearward to remove.
For Installation, reverse Removal procedures.

SPEEDOMETER/ODOMETER
It is not necessary to remove instrument clus­
ter from vehicle for speedometer replacement. When removing speedometer (Fig. 4) from cluster,
gauge must be pulled straight out, not twisted, or
damage to gauge pin and/or printed circuit board
may result. (1) Disconnect negative cable from battery.
(2) Remove bezel. Refer to Cluster Bezel Removal.
(3) Remove cluster mask and lens. Refer to Cluster
Mask and Lens Removal. (4) Remove mounting screws retaining speedome­
ter/odometer to housing.
(5) Pull speedometer/odometer rearward to remove.
For Installation, reverse Removal procedures.