sensor DODGE TRUCK 1993 Service Owner's Manual

•

ELECTRICAL
8A - 17
DIAGNOSTIC
TROUBLE
CODES

Diagnostic trouble codes are 2 digit numbers
flashed on Malfunction Indicator lamp (Check En­
gine) that identify which circuit is bad. In most cases
they do not identify which component in a circuit is
bad. A DTC description can be read using the DRB II scan tool. Refer to Group 14 - Fuel Systems for more
information. Therefore, a DTC is only a result, not
necessarily the reason for the problem. However, in
some cases, as a result of the design of the driveabil- ity test procedure, a DTC can be the reason for the
problem. It is important that the test procedure be followed in order to understand what the DTC of the
on-board diagnostic system are trying to tell.

HOW
TO
USE
MALFUNCTION
INDICATOR
(CHECK

ENGINE)
LAMP
FOR
FAULT
CODES
To activate this function cycle the ignition switch
on-off-on-off-on within 5 seconds and any DTC stored
in the Powertrain Control Module will be displayed.
The Check Engine lamp will display a DTC by flash­ ing on and off. There is a short pause between
flashes and a longer pause between digits. All codes
displayed are two digit numbers with a four second
pause between codes. An example of a code is as follows:
(1) Lamp on for 2 seconds, then turns off.
(2) Lamp flashes 4 times pauses and then flashes

1.
(3) Lamp pauses for 4 seconds, flashes 4 times,
pauses and then flashes 7 times.
The two codes are 41 and 47. Any number of codes
can be displayed (maximum of 8 faults can be stored) as long as they are in memory. The lamp will flash
until all of them (including 55) are displayed (55 =
End of test).

CHARGING
SYSTEM
FAULT
CODES
See Generator Fault Code Chart for fault codes
which apply to the charging system. Refer to the
Powertrain Diagnostic Procedures Manual to diag­
nose an On-Board Diagnostic System, Fault Code.
GENERATOR
DIAGNOSTIC
TROUBLE
CODE
(DTC)

DTC
Type
Malfunction

Indicator
Lamp
Circuit
When
Monitored

By
the
Logic

Module
When
Put Into
Memory
Actuator

Test
Sensor

Read
Test

41 Fault
Yes
Generator Field

Control
(Charging
System)
All the
time
when
the ignition switch

is
on.
An
open or shorted condition in
the generator
field

control circuit.
Yes

None

46 Fault
Yes
Charging
System

Voltage
All the
time
when the

engine
is
running.
If the
battery
sense
voltage is
more than 1 volt
above
the

desired
control voltage for
more than 20
seconds.
None

Yes

47 Fault
Yes
Charging
System

Voltage
Engine
rpm
above

1,500 rpm Battery voltage
1
volt
less

than set point during engine
operation and no
change
in

voltage
during
internal
PCM
test performed on generator field.
None

Yes

J938A-20

•

IGNITION
SYSTEMS
8D
- 1
CONTENTS

page page
COMPONENT IDENTIFICATION/SYSTEM DIAGNOSTICS/SERVICE PROCEDURES
7
OPERATION
1
IGNITION SWITCH
25

COMPONENT REMOVAL/INSTALLATION
..... 18
SPECIFICATIONS
28

COMPONENT
IDENTIFICATION/SYSTEM OPERATION
INDEX
page

Automatic
Shut Down (ASD) Relay
1
Camshaft Position Sensor
2

Crankshaft Position Sensor
2

Distributors
3

Engine Coolant
Temperature
Sensor
...........
4

General
Information
1
page

Ignition
Coil
3
Intake
Manifold Charge
Air
Temperature
Sensor
. . 4

Manifold Absolute Pressure (MAP) Sensor
4
Powertrain
Control
Module (PCM)
. 5

Throttle
Position Sensor
5

GENERAL
INFORMATION
Throughout this group, references
are
made
to
par­
ticular vehicle models
by
alphabetical designation
or

by
the
particular vehicle nameplate.
A
chart showing a breakdown
of
alphabetical designations
is
included
in
the
Introduction group
at the
beginning
of
this
manual. 5.9L
gas
powered engines will
be
referred
to as ei­

ther: LDC (Light Duty Cycle),
or
HDC (Heavy Duty Cycle). This section
of the
group, Component Identifica­
tion/System Operation, will discuss ignition system operation
and
will identify ignition system compo­

nents.
For diagnostic procedures
and
adjustments, refer
to

the Diagnostics/Service Procedures section
of
this
group.
For removal
and
installation
of
ignition system
components, refer
to the
Component Removal/Instal­
lation section
of
this group. For other useful information, refer
to
On-Board
Di­

agnostics
in the
General Diagnosis sections
of
Group
14,
Fuel System
in
this manual. For operation
of the DRB II
Diagnostic Scan Tool,
refer
to the
appropriate Powertrain Diagnostic Proce­
dures service manual.
An Ignition specifications section
is
included
at the

end
of
this group.
A
general Maintenance Schedule (mileage intervals)
for
ignition related items
can be
found
in
Group
0,
Lubrication and Maintenance. This
schedule
can
also
be
found
in the
Owners Manual.

IGNITION
SYSTEMS
The ignition systems used
on all
engines
are
basi­
cally identical. Similarities
and
differences between
the systems will
be
discussed.
A sequential multi-port fuel injection system
is

used
on all gas
powered engines.
The ignition system
is
controlled
by the
powertrain
control module (PCM)
on all
engines.
The
PCM
was

formerly referred
to as the
SBEC
or
engine control­ ler.
The ignition system consists
of:

• Spark Plugs
• Ignition Coil
• Secondary Ignition Cables
• Ignition distributor. Contains rotor
and
camshaft
position sensor • Powertrain Control Module (PCM)
• Crankshaft Position Sensor

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

the engine compartment (Fig.
1). As one of its
func­

tions,
the ASD
relay will supply battery voltage
to
the ignition coil.
The
ground circuit
for the
ASD
re­

lay
is
controlled
by the
powertrain control module (PCM).
The PCM
regulates
ASD
relay operation
by
switching
the
ground circuit on-and-off.

IGNITION
SYSTEMS

8D
- 2
IGNITION
SYSTEMS

•

A/C
CLUTCH RELAY STARTER RELAY
DATA LINK CONTROL

CONNECTOR
MODULE J9314-164
Fig.
1
Auto
Shut Down
Relay

CAMSHAFT POSITION SENSOR
The camshaft position sensor is located in the igni­
tion distributor (Fig. 2) on all engines.
Fig.
2 Camshaft Position
Sensor—
Typical

The camshaft position sensor contains a hall effect
device called a sync signal generator to generate a
fuel sync signal. This sync signal generator detects a
rotating pulse ring (shutter) on the distributor shaft.
The pulse ring rotates 180 degrees through the sync signal generator. Its signal is used in conjunction
with the crankshaft position sensor to differentiate
between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their re­ spective cylinders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following oc­

curs:
The interruption of magnetic field causes the
voltage to switch high resulting in a sync signal of approximately 5 volts.
When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following oc­

curs:
The change of the magnetic field causes the sync signal voltage to switch low to 0 volts. For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group. For removal and installation of this component, re­
fer to the Component Removal/Installation section of this group.

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

Fig.
3 Crankshaft Position Sensor—Typical

*
Engine speed and crankshaft position are provided
through the crankshaft position sensor. The sensor generates pulses that are the input sent to the pow­
ertrain control module (PCM). The PCM interprets
the sensor input to determine the crankshaft posi­
tion. The PCM then uses this position, along with other inputs, to determine injector sequence and ig­
nition timing.
The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.

SENSOR
OPERATION-3.9L
ENGINE
The flywheel/drive plate has groups of notches at
its outer edge. On 3.9L V-6 engines, there are three sets of double notches and three sets of single
notches (Fig.
4).

The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input to the PCM.
The engine will not operate if the PCM does not re­
ceive a crankshaft position sensor input.
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.

•

IGNITION
SYSTEMS
8D - 3 For removal and installation of this sensor, refer to
the Component Removal/Installation section of this
group.
CRANKSHAFT
POSITION
SENSOR

NOTCHES- FLYWHEEL CRANKSHAFT
POSITION-
SENSOR

NOTCHES* .FLYWHEEL

J9314-88
—^^j^jV^
J9314-89

Fig.
4
Sensor
Operation—3.9L
Engine

SENSOR
OPERATION'-5.2U5.9L
ENGINES On 5.2L and 5.9L engines, the flywheel/drive plate
has 8 single notches, spaced every 45 degrees, at its outer edge (Fig. 5).
The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input to the PCM. For each engine revolution, there are 8
pulses generated on V-8 engines.
The engine will not operate if the PCM does not re­
ceive a crankshaft position sensor input. For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

DISTRIBUTORS
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.

ALL
ENGINES All engines are equipped with a camshaft driven
mechanical distributor, containing a shaft driven dis­
tributor rotor. They are equipped with an internal camshaft position (fuel sync) sensor. This sensor pro­
vides fuel injection synchronization and cylinder identification.
Distributors do not have built in centrifugal or vac­
uum assisted advance. Base ignition timing and all
timing advance is controlled by the powertrain con­
trol module (PCM). Because ignition timing is con-
Fig.
5
Sensor
Opera tion—5.2L/5.9L
Engine

trolled by the PCM, base ignition timing is not adjustable on any of these engines.
The distributor is held to the engine in the conven­
tional method using a holddown clamp and bolt. Al­
though the distributor can be rotated, it will
have no effect on ignition timing.
All distributors contain an internal oil seal that
prevents oil from entering the distributor housing.
The seal is not serviceable.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

IGNITION
COIL
Battery voltage is supplied to the ignition coil pos­
itive terminal from the ASD relay. The powertrain control module (PCM) opens and
closes the ignition coil ground circuit for ignition coil operation. Base ignition timing is not adjustable on any
engine. By controlling the coil ground circuit, the
PCM is able to set the base timing and adjust the ig­ nition timing advance. This is done to meet changing engine operating 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. • 3.9L/5.2L/5.9L LDC-Gas Engines: The coil is
mounted to a bracket that is bolted to the front of the right engine cylinder head (Fig. 6). This bracket is also used to mount the automatic belt tensioner.

8D
- 4
IGNITION
SYSTEMS

•
Fig. 6 ignition Coil—3.9L/5.2L/5.9L
LDC-Gas
Engines Fig. 7 Ignition Coil—5.9L
HDC-Gas
Engine
• 5.9L HDC-Gas Engines: The coil is mounted to a
bracket that is bolted to the automatic belt tensioner mounting bracket (Fig. 7).
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

ENGINE COOLANT TEMPERATURE
SENSOR
The sensor provides an input voltage to the power-
train control module (PCM) relating coolant temper­ ature. The PCM uses this input, along with inputs
from other sensors, to determine injector pulse width and ignition timing. As coolant temperature varies,
the coolant temperature sensor resistance will
change, resulting in a different input voltage to the
PCM. When the engine is cold, the PCM will operate in
the Open Loop Cycle. It will demand slightly richer air-fuel mixtures and higher idle speeds, until nor­ mal operating temperatures are reached. Refer to
Modes Of Operation in Group 14, Fuel System for a
description of Open and Closed Loop operation.
The sensor is installed in the intake manifold near
the thermostat housing (Fig. 8).
Fig. 8 Coolant Temperature Sensor—Typical
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group. For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

INTAKE MANIFOLD CHARGE
AIR
TEMPERATURE

SENSOR
The sensor element extends into the intake mani­
fold air stream. It provides an input voltage to the
powertrain control module (PCM) indicating intake
manifold air temperature. The input from this sensor is used along with inputs from other sensors to de­
termine injector pulse width. As the temperature of
the air-fuel stream in the manifold varies, the sensor
resistance will change. This will result in a different input voltage to the PCM. For more information, re­
fer to Group 14, Fuel System. This sensor is installed in the intake manifold

(Figs.
9 or 10). For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group. For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

MANIFOLD ABSOLUTE
PRESSURE
(MAP)
SENSOR
The MAP sensor reacts to absolute pressure in the
intake manifold and provides an input voltage to the
powertrain control module (PCM). As engine load changes, manifold pressure varies, causing the MAP
sensor voltage to change. This change results in a
different input voltage to the PCM. The input volt­ age level supplies the PCM with information. This
relates to ambient barometric pressure during engine

•

IGNITION
SYSTEMS
8D - 5

THROTTLE
^
BODY
u

BRACKET
y^SUPPORT
BRACKET
/ |

CHARGE
AIR

ijmmmmk
TEMPERATURE
SENSOR
THROTTLE

BODY

Fig.
9
Sensor
Location—3.9L Engine—Typical
INTAKE MANIFOLD
'b AIR TEMPERATURE

SENSOR

J9314-162

Fig.
10
Sensor
Location—5.2L/5.9L
Engines—Typical
start-up (cranking) and to engine load while the en­
gine is running. The PCM uses this input, along with
inputs from other sensors, to adjust air-fuel mixture.
For more information, refer to Group 14, Fuel Sys­
tem.
The MAP sensor is mounted to the throttle body
(Fig. 11). It is connected to the throttle body with an
L-shaped rubber fitting and to the PCM electrically. For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group. For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.

POWERTRAIN CONTROL MODULE
(PCM) The powertrain control module (PCM) is located in
the engine compartment behind the battery (Fig. 12).
The PCM was formerly referred to as the SBEC or engine controller. The ignition system is controlled by the PCM. Base ignition timing by rotation of distributor
is not adjustable.
MANIFOLD

ABSOLUTE
PRESSURE
SENSOR

TORQUE CONVERTER CLUTCH RELAY
ELECTRICAL
Jlp^

CONNECTOR
^gis!—

Fig.
11 MAP Sensor—Typical
A/C
CLUTCH RELAY STARTER RELAY
AUTO
SHUTDOWN RELAY FUEL PUMP RELAY
DATA LINK
CONNECTOR POWERTRAIN
CONTROL
MODULE
J9314-164

Fig.
12 PCM Location—Typical The PCM opens and closes the ignition coil ground
circuit to operate the ignition coil. This is done to ad­
just ignition timing, both initial (base) and advance, for changing engine operating conditions.
The amount of electronic spark advance provided
by the PCM is determined by five input factors: Cool­ ant temperature, engine rpm, intake manifold tem­
perature, manifold absolute pressure and throttle
position.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.
For diagnostics, refer to the appropriate Powertrain
Diagnostic Procedures service manual for operation
of the DRB II scan tool.

THROTTLE
POSITION
SENSOR
The sensor is mounted on the throttle body (Fig.

13).
It is connected to the throttle blade shaft. The
sensor is a variable resistor. It provides the power-
train control module (PCM) with an input signal (voltage) that represents throttle blade position. As

8D
- 6
IGNITION
SYSTEMS

• the position of the throttle blade changes, the resis­
tance of the sensor changes.
The PCM supplies approximately 5 volts to the
sensor. The sensor output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the sen­ sor. This will vary in an approximate range of from 1
volt at minimum throttle opening (idle), to 4 volts at
wide open throttle. Along with inputs from other sen­
sors,
the PCM uses the sensor input to determine
current engine operating conditions. It also will ad­
just fuel injector pulse width and ignition timing.
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.
MANIFOLD ABSOLUTE
Fig.
13
Throttle
Position
Sensor—
Typical

•

IGNITION
SYSTEMS
80 - 7
DIAGNOSTICS/SERW1CE
PROCEDURES

INDEX

page

Automatic Shut Down (ASD) Relay
7
Camshaft Position
Sensor
Test
...............
7

Crankshaft Position
Sensor
Test
8

Distributor
Cap
8

Distributor
Rotor
8
Engine
Coolant Temperature
Sensor
Test
10

General
Information
7

Ignition
Coil
8

Ignition
Secondary
Circuit
Diagnosis
10

GENERAL
INFORMATION
This section
of the
group, Diagnostics/Service Pro­
cedures, will discuss basic ignition system diagnos­
tics
and
service adjustments. For system operation
and
component identification,
refer
to the
Component Identification/System Opera­
tion section
of
this group. For removal
or
installation
of
ignition system com­
ponents, refer
to the
Component Removal/Installa­
tion section
of
this group. For other useful information, refer
to
On-Board
Di­

agnostics
in the
General Diagnosis sections
of
Group
14,
Fuel System
in
this manual. For operation
of the DRB II
Diagnostic Scan Tool,
refer
to the
appropriate Powertrain Diagnostic Proce­
dures service manual.

AUTOMATIC SHUT DOWN
(ASD)
RELAY
Refer
to
Relays—Operation/Testing
in the
Group

14,
Fuel System section
of
this service manual.

CAMSHAFT POSITION SENSOR TEST
The camshaft position sensor
is
located
in the
dis­
tributor
on all
engines. To perform
a
complete test
of
this sensor
and its

circuitry, refer
to the DRB II
diagnostic scan tool.
Also refer
to the
appropriate Powertrain Diagnostics
Procedures manual.
To
test
the
sensor only, refer
to

the following: For this test,
an
analog (non-digital) voltmeter
is needed.
Do not
remove
the
distributor connector from
the
distributor. Using small paper clips, insert
them into
the
backside
of the
distributor wire har­ ness connector
to
make contact with
the
terminals.
Be sure that
the
connector
is not
damaged when
in­
serting
the
paper clips. Attach voltmeter leads
to

these paper clips. (1) Connect
the
positive (
+
)
voltmeter lead into
the sensor output wire. This
is at
done
the
distribu­ tor wire harness connector.
For
wire identification,
refer
to
Group
8W,
Wiring Diagrams.
page

Ignition
Timing
12

Intake Manifold Charge
Air
Temperature
Sensor
Test
12

Manifold Absolute Pressure (MAP)
Sensor
Test
. 12

Oxygen
Sensor
Tests
17
Powertrain Control Module (PCM)
............
14

Spark
Plug Secondary Cables
16

Spark
Plugs
............................
14

Throttle
Position
Sensor
Test
17

(2) Connect
the
negative
(-)
voltmeter lead into
the

ground wire.
For
wire identification, refer
to
Group
8W, Wiring Diagrams.
(3)
Set the
voltmeter
to the 15
Volt
DC
scale. (4) Remove distributor
cap
from distributor
(two

screws). Rotate (crank)
the
engine until
the
distribu­
tor rotor
is
pointed towards
the
rear
of
vehicle.
The

movable pulse ring should
now be
within
the
sensor
pickup.
(5) Turn ignition
key to ON
position. Voltmeter
should read approximately
5.0
volts.
(6)
If
voltage
is not
present, check
the
voltmeter
leads
for a
good connection.
(7)
If
voltage
is
still
not
present, check
for
voltage
at
the
supply wire.
For
wire identification, refer
to

Group
8W,
Wiring Diagrams.
(8)
If
voltage
is not
present
at
supply wire, check
for voltage
at
pin-7
of
powertrain control module (PCM) 60-way connector. Leave
the PCM
connector
connected
for
this test. (9)
If
voltage
is
still
not
present, perform vehicle
test using
the DRB II
diagnostic scan tool. (10)
If
voltage
is
present
at
pin-7,
but not at the

supply wire: (a) Check continuity between
the
supply wire.
This
is
checked between
the
distributor connector and pin-7
at the PCM. If
continuity
is not
present,
repair
the
harness
as
necessary. (b) Check
for
continuity between
the
camshaft
position sensor output wire
and
pin-44
at the PCM.
If continuity
is not
present, repair
the
harness
as
necessary. (c) Check
for
continuity between
the
ground cir­
cuit wire
at the
distributor connector
and
ground.
If continuity
is not
present, repair
the
harness
as
necessary. (11) While observing
the
voltmeter, crank
the en­

gine with ignition switch.
The
voltmeter needle should fluctuate between
0 and 5
volts while
the en­

gine
is
cranking. This verifies that
the
camshaft
po­
sition sensor
in the
distributor
is
operating properly
and
a
sync pulse signal
is
being generated.

8D
- 8
IGNITION
SYSTEMS

• If sync pulse signal is not present, replacement of
the camshaft position sensor is necessary. For removal or installation of ignition system com­
ponents, refer to the Component Removal/Installa­
tion section of this group.
For system operation and component identification,
refer to the Component Identification/System Opera­
tion section of this group.

CRANKSHAFT POSITION
SENSOR
TEST
To perform a complete test of this sensor and its
circuitry, refer to the DRB II diagnostic scan tool.
Also refer to the appropriate Powertrain Diagnostics
Procedures manual. To test the sensor only, refer to
the following: The sensor is located on the top of cylinder block
near the rear of right cylinder head (Fig. 1). (1) Near the rear of intake manifold, disconnect
sensor pigtail harness connector from main wiring
harness. Fig. 1 Crankshaft Position Sensor—Typical
(2) Place an ohmmeter across terminals B and C
(Fig. 2). Ohmmeter should be set to lK-to-lOK scale
for this test. The meter reading should be open (no
resistance). Replace sensor if a low resistance is indi­ cated.

DISTRIBUTOR
CAP INSPECTION Remove the distributor cap and wipe it clean with
a dry lint free cloth. Visually inspect the cap for
cracks, carbon paths, broken towers, or damaged ro­
tor button (Figs. 3 and 4). Also check for white de­
posits on the inside (caused by condensation entering VIEW LOOKING INTO

CPS
CONNECTOR
J938D-7

Fig. 2 Sensor Connector the cap through cracks). Replace any cap that dis­
plays charred or eroded terminals. The machined surface of a terminal end (faces toward rotor) will in­
dicate some evidence of erosion from normal opera­
tion. Examine the terminal ends for evidence of mechanical interference with the rotor tip. Fig. 3 Cap Inspection—External—Typical

DISTRIBUTOR ROTOR
Visually inspect the rotor (Fig. 5) for cracks, evi­
dence of corrosion, or the effects of arcing on the
metal tip. Also check for evidence of mechanical in­
terference with the cap. Some charring is normal on
the end of the metal tip. The silicone-dielectric-var­ nish-compound applied to the rotor tip for radio in­
terference noise suppression, will appear charred.
This is normal. Do not remove the charred com­ pound. Test the spring for insufficient tension. Re­
place a rotor that displays any of these adverse conditions.
IGNITION COIL

To perform a complete test of the ignition coil and
its circuitry, refer to the DRB II diagnostic scan tool.

8D
- 10
IGNITION
SYSTEMS

• Arcing at the tower will carbonize the cable boot,
which if it is connected to a new ignition coil, will cause the coil to fail. If the secondary coil cable shows any signs of dam­

age,
it should be replaced with a new cable and new
terminal. Carbon tracking on the old cable can cause
arcing and the failure of a new ignition coil.

ENGINE
COOLANT
TEMPERATURE
SENSOR
TEST
To perform a complete test of this sensor and its
circuitry, refer to the DRB II diagnostic scan tool.
Also refer to the appropriate Powertrain Diagnostics
Procedures manual. To test the sensor only, refer to
the following: The sensor is located in a water passage of the in­
take manifold next to the thermostat housing (Fig.
8).
(1) Disconnect wire harness connector from sensor
(Fig. 8). On engines with air conditioning, do not pull
directly on wiring harness. Fabricate an L-shaped
hook tool from a coat hanger (approximately eight inches long). Place the hook part of tool under the
connector for removal. The connector is snapped onto
the sensor. It is not equipped with a lock type tab.
COOLANT

TEMPERATURE
SENSOR
SENSOR RESISTANCE (OHMSJ
V

J9314-78

Fig. 8 Coolant Temperature Sensor—Typical (2) Test the resistance of the sensor with a high in­
put impedance (digital) volt-ohmmeter. The resis­ tance should be less than 1340 ohms at normal
engine operating idle temperature. For resistance
values, refer to the Sensor Resistance chart. Replace
the sensor if it is not within the range of resistance specified in the chart.
(3) Test continuity of the wire harness. This is
done between powertrain control module (PCM) wire
harness connector terminal-2 and the sensor connec­
tor terminal. Also check continuity between wire harness terminal-4 to the sensor connector terminal. Repair the wire harness if an open circuit is indi­
cated.
TEMPERATURE

RESISTANCE
(OHMS)

C
F
MIN
MAX

-40 -40 291,490 381,710
-20
-4
85,850
108,390
-10 14
49,250 61,430

0
32 29,330
35,990
10 50 17,990 21,810
20 68 11,370 13,610

25
77 9,120 10,880
30 86
7,370

8,750

40 104

4,900
5,750

50 122
3,330 3,880

60 140 2,310

2,670

70 158
1,630 1,870

80 176
1,170 1,340

90 194
860
970
100 212 640
720
110 230 480 540
120 248 370 410

J928D-4

IGNITION
SECONDARY
CIRCUIT
DIAGNOSIS

CHECKING FOR SPARK

CAUTION:
When
disconnecting a
high
voltage
cable

from
a spark
plug
or
from
the
distributor
cap,
twist
the rubber
boot
slightly
(1/2
turn)
to
break
it
loose.
Grasp
the
boot
(not the cable) and
pull
it off
with
a

steady,
even force.

(1) Disconnect the ignition coil secondary cable
from center tower of the distributor cap. Hold the ca­
ble terminal approximately 12 mm (1/2 in.) from a good engine ground (Fig. 9).
CHECK
HERE

FOR
SPARK
IGNITION

COIL
918D-18

Fig. 9 Checking for Spark—Typical