1993 DODGE TRUCK ignition

14
- 34
FUEL SYSTEM

width accordingly. During Open Loop operation, the
PCM ignores the 02 sensor input and adjusts injector
pulse width to a preprogrammed value (based on other sensor inputs).

EXHAUST
PIPE J9214-5
Fig. 8 Oxygen Sensor Location—3.9L/5.2L/5.9L LDC Engine
5,9L HDC
ENGINE
Dual 02 sensors are used on the 5.9L heavy duty
cycle (HDC) engine (Fig. 9). Each sensor will monitor
the oxygen content in each exhaust downpipe. The left sensor monitors the odd numbered cylinders (1-3-5-7). The right sensor monitors the even numbered
cylinders (2-4-6-8),
For sensor operational information, refer to the
paragraphs in the previous 3.9L/5.2/5.9L LDC oxygen sensor section. Fig. 9 Oxygen Sensor Location—5.9L HDC Engine

OVERDRIVE/OWERRIDE
SWITCH
On vehicles equipped with overdrive, the power-
train control module (PCM) regulates the 3-4 over­ drive up-shift and down-shift through the overdrive solenoid. An override switch is located on the instru­
ment panel. The overdrive/override switch is normally closed. It
opens when the operator presses the switch. The
transmission will not enter overdrive when the oper­ ator presses the override switch. The transmission
downshifts if the operator presses the override switch
while in overdrive.
The overdrive switch circuit contains two other
switches: A transmission thermo-switch and a cool­
ant temperature switch. When either switch opens,
the transmission will not shift into overdrive, or downshift (if already in overdrive).
Refer to Group 21 for more information.

PARK/NEUTRAL SWITCH-PCM
INPUT
The park/neutral switch is located on the transmis­
sion housing and provides an input to the powertrain
control module (PCM). This will indicate that the au­
tomatic transmission is in Park, Neutral or a drive
gear selection. This input is used to determine idle
speed (varying with gear selection), fuel injector
pulse width and ignition timing advance. Refer to Group 21, Transmissions, for testing, replacement
and adjustment information.

POWER
GROUND
The power ground is used to control ground circuits
for the following powertrain control module (PCM)
loads:

• Generator field winding
• 8 volt (PCM) power supply
• Fuel injectors
• Ignition coil

SCI
RECEIVE-PCM
INPUT
SCI Receive is the serial data communication re­
ceive circuit for the DRB II scan tool. The powertrain
control module (PCM) receives data from the DRB II
through the SCI Receive circuit.

SPEED
CONTROL-PCM INPUT
The speed control system provides three separate
inputs to the powertrain control module (PCM); On/ Off, Set and Resume. The On/Off input informs the
PCM that the speed control system has been acti­
vated. The Set input informs the PCM that a fixed
vehicle speed has been selected. The Resume input indicates to the PCM that the previous fixed speed is
requested. The speed control operating range is from 50 km/h
to 142 km/h (35 to 85 mph). Inputs that effect speed control operation are:
• Park/neutral switch
• Vehicle speed sensor
• Throttle position sensor Refer to Group 8H for further speed control infor­
mation.

•

FUEL SYSTEM
14 - 35
SENSOR
RETURN—PCM
INPUT

Sensor Return provides a low noise ground refer­
ence for all system sensors.

THROTTLE POSITION
SENSOR
(TPS)-PCM
INPUT
The throttle position sensor (TPS) is mounted on
the throttle body (Fig. 10). The TPS is a variable re­ sistor that provides the powertrain control module (PCM) with an input signal (voltage) that represents
throttle blade position. The sensor is connected to the
throttle blade shaft. As the position of the throttle
blade changes, the resistance of the TPS changes. The PCM supplies approximately 5 volts to the

TPS.
The TPS output voltage (input signal to the PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
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 TPS input to determine cur­
rent engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
MANIFOLD ABSOLUTE
Fig.
10
Throttle
Position Sensor—Typical

VEHICLE
SPEED
SENSOR—PCM
INPUT
The speed sensor (Fig. 11) is located in the exten­
sion housing of the transmission (2WD) or on the
transfer case extension housing (4WD). The sensor input is used by the powertrain control module (PCM) to determine vehicle speed and distance trav­
eled. The speed sensor generates 8 pulses per sensor rev­
olution. These signals, in conjunction with a closed
throttle signal from the throttle position sensor, indi­
cate a closed throttle deceleration to the PCM. When the vehicle is stopped at idle, a closed throttle signal
is received by the PCM (but a speed sensor signal is
not received).
Under deceleration conditions, the PCM adjusts the
idle air control (IAC) motor to maintain a desired
MAP value. Under idle conditions, the PCM adjusts
the IAC motor to maintain a desired engine speed.
Fig.
11 Vehicle
Speed
Sensor—Typical

AIR
CONDITIONING
(A/C)
CLUTCH RELAY—PCM
OUTPUT
The powertrain control module (PCM) activates the
A/C compressor through the A/C clutch relay. The
PCM regulates A/C compressor operation by switch­
ing the ground circuit for the A/C clutch relay on and off. The relay is located in the engine compart­
ment (Fig. 12).

A/C
CLUTCH RELAY STARTER RELAY
DATA LINK CONTROL
CONNECTOR MODULE
J9314-164

Fig.
12 Relay Location
When the PCM receives a request for A/C from A/C
evaporator switch, it will adjust idle air control (IAC)
motor position. This is done to increase idle speed.
The PCM will then activate the A/C clutch through
the A/C clutch relay. The PCM adjusts idle air con-

trol (IAC) stepper motor position to compensate for
increased engine load from the A/C compressor.
By switching the ground path for the relay on and
off, the PCM is able to cycle the A/C compressor
clutch. This is based on changes in engine operating
conditions. If, during A/C operation, the PCM senses
low idle speeds or a wide open throttle condition, it
will de-energize the relay. This prevents A/C clutch engagement. The relay will remain de-energized un­
til the idle speed increases or the wide open throttle condition exceeds 15 seconds or no longer exists. The
PCM will also de-energize the relay if coolant tem­
perature exceeds 125°C (257°F).

IDLE
AIR
CONTROL
(IAC)
MOTOR-PCM OUTPUT
The IAC motor is mounted to the back of the throt­
tle body (Fig. 13) and is controlled by the powertrain control module (PCM).
AAANIFOLD ABSOLUTE

PRESSURE
SENSOR
MOUNTING
SCREWS
MAP SENSOR

THROTTLE

POSITION
SENSOR
J9314-86

Fig.
13 IAC Motor—Typical The throttle body has an air control passage that
provides air for the engine at idle (the throttle plate is closed). The IAC motor pintle protrudes into the
air control passage (Fig. 14) and regulates air flow
through it. Based on various sensor inputs, the pow­
ertrain control module (PCM) adjusts engine idle speed by moving the IAC motor pintle in and out of
the air control passage. The IAC motor is positioned
when the ignition key is turned to the On position.
A (factory adjusted) set screw is used to mechani­
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are
controlled by the PCM.
RUBBER
FITTING

J9314-87

Fig.
14
Throttle
Body
Air Control
Passage

AUTO SHUT DOWN (ASD) RELAY—PCM OUTPUT
The ASD relay is located in the engine compart­
ment (Fig. 12). The ASD supplies battery voltage to the fuel pump,
fuel injector, ignition coil, generator field winding and oxygen (02) sensor(s) heating element. The
ground circuit for the coil in the ASD relay is con­
trolled by the powertrain control module (PCM). The PCM operates the relay by switching the ground cir­
cuit on and off. The fuel pump relay is controlled by the PCM
through same circuit that the ASD relay is con­ trolled.
GENERATOR FIELD-PCM OUTPUT

The powertrain control module (PCM) regulates
the charging system voltage within a range of 12.9 to 15.0 volts. Refer to Group 8A for charging system in­
formation.

GENERATOR LAMP-PCM OUTPUT
If the powertrain control module (PCM) senses a
low charging condition in the charging system, it
will illuminate the generator lamp on the instrument
panel. For example, during low idle with all accesso­
ries turned on, the light may momentarily go on. Once the PCM corrects idle speed to a higher rpm,
the light will go out. Refer to Group 8A for charging system information.

ELECTRIC
EXHAUST GAS RECIRCULATION

TRANSDUCER
(EET)
S0LEN0ID-PCM OUTPUT

Refer to Group 25, Emission Control System for in­
formation. See Electric Exhaust Gas Recirculation
Transducer (EET) Solenoid.

SRI
LAMP-PCM OUTPUT
The instrument panel mounted service reminder
indicator (SRI) lamp was formerly referred to as the
emission maintenance reminder (EMR) lamp. It is

•

FUEL SYSTEM
14 - 37 used only on vehicles equipped with the 5.9L heavy
duty cycle (HDC) engine. Refer to Group 25, Emis­
sion Control System for information.

EVAP CANISTER PURGE SOLENOID-PCM

OUTPUT
Refer to Group 25, Emission Control System. See
EVAP Canister Purge Solenoid.

FUEL INJECTORS-PCM
OUTPUT
The fuel injectors are attached to the fuel rail (Fig.

15).
3.9L engines use six injectors. 5.2L and 5.9L en­
gines use eight injectors. The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the in­
take valve ports of the cylinder head. The engine
wiring harness connector for each fuel injector is equipped with an attached numerical tag (INJ 1, INJ 2 etc.). This is used to identify each fuel injector with
its respective cylinder number. The injectors are energized individually in a se­
quential order by the powertrain control module (PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust injector pulse width based on various inputs it re­
ceives. During start up, battery voltage is supplied to the
injectors through the ASD relay. When the engine is
operating, voltage is supplied by the charging sys­
tem. The PCM determines injector pulse width based on various inputs.
FUEL

INJECTOR
J9214-30

Fig.
15
Fuel
injectors—Typical
MALFUNCTION INDICATOR LAMP-PCM OUTPUT

The malfunction indicator lamp (formerly referred
to as the check engine lamp) illuminates at the bot­
tom of the instrument panel each time the ignition key is turned on. It will stay on for three seconds as a bulb test. If the powertrain control module (PCM) receives an
incorrect signal, or no signal from certain sensors or
emission related systems, the lamp is turned on. This
is a warning that the PCM has recorded a system or
sensor malfunction. In some cases, when a problem is
declared, the PCM will go into a limp-in mode. This
is an attempt to keep the system operating. It signals an immediate need for service. The lamp can also be used to display a diagnostic
trouble code (DTC). Cycle the ignition switch
On-Off-
On-Off-On within three seconds and any codes stored
in the PCM memory will be displayed. This is done
in a series of flashes representing digits. Refer to On-
Board Diagnostics in the General Diagnosis section
of this group for more information.

IGNITION COIL-PCM OUTPUT
System voltage is supplied to the ignition coil pos­
itive terminal. The powertrain control module (PCM)
operates the ignition coil. Base (initial) ignition
timing is not adjustable. The PCM adjusts ignition
timing to meet changing engine operating conditions. The ignition coil is located near the front of the
right cylinder head (Fig. 16 or 17). Refer to Group 8D, Ignition System for additional
information.

Fig.
16 Ignition Coii-3.9U5.2U5.9L
LDC-Gas
Engine

SCI
TRANSMIT—PCM OUTPUT
SCI Transmit is the serial data communication
transmit circuit for the DRB II scan tool. The power- train control module (PCM) transmits data to the DRB II through the SCI Transmit circuit.

14 - 38
FUEL SYSTEM

•
Fig.
17 Ignition Coil—5.9L
HDC-Gas
Engine

SHIFT INDICATOR-PCM
OUTPUT
Vehicles equipped with manual transmissions have
an Up-Shift indicator lamp. The lamp is controlled
by the powertrain control module (PCM). The lamp illuminates on the instrument panel to indicate when
the driver should shift to the next highest gear for
best fuel economy. The PCM will turn the lamp off after 3 to 5 seconds if the shift of gears is not per­
formed. The up-shift light will remain off until vehi­ cle stops accelerating and is brought back to range of
up-shift light operation. This will also happen if ve­
hicle is shifted into fifth gear. The indicator lamp is normally illuminated when
the ignition switch is turned on and it is turned off
when the engine is started up. With the engine run­
ning, the lamp is turned on/off depending upon en­
gine speed and load.

SPEED
CONTROL-PCM
OUTPUT
Speed control operation is regulated by the power-
train control module (PCM). The PCM controls the
vacuum to the throttle actuator through the speed
control vacuum and vent solenoids. Refer to Group
8H for Speed Control Information.

TACHOMETER—PCM
OUTPUT
The powertrain control module (PCM) supplies en­
gine rpm values to the instrument cluster tachome­ ter. Refer to Group 8E for tachometer information.

OPEN
LOOP/CLOSED LOOP MODES
OF

OPERATION

As input signals to the powertrain control module
(PCM) change, the PCM adjusts its response to the
output devices. For example, the PCM must calculate
different injector pulse width and ignition timing for
idle than it does for wide open throttle (WOT). There
are several different modes of operation that deter­
mine how the PCM responds to the various input sig­
nals.
MODES

• Open Loop
• Closed Loop During Open Loop modes, the powertrain control
module (PCM) receives input signals and responds
only according to preset PCM programming. Input
from the oxygen (02) sensor(s) is not monitored dur­
ing Open Loop modes.
During Closed Loop modes, the PCM will monitor
the oxygen (02) sensor input. This input indicates to
the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the ex­
haust oxygen content through the 02 sensor, the
PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined
with low emission engine performance.
The fuel injection system has the following modes
of operation:
• Ignition switch ON • Engine start-up (crank)
• Engine warm-up
• Idle
• Cruise • Acceleration
• Deceleration
• Wide open throttle (WOT)
• Ignition switch OFF The ignition switch On, engine start-up (crank),
engine warm-up, acceleration, deceleration and wide
open throttle modes are Open Loop modes. The idle and cruise modes, (with the engine at operating tem­
perature) are Closed Loop modes.

IGNITION
SWITCH
(KEY-ON)
MODE
This is an Open Loop mode. When the fuel system
is activated by the ignition switch, the following ac­
tions occur:
• The powertrain control module (PCM) pre-posi-
tions the idle air control (IAC) motor. • The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel strategy.
• The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based
on this input.
• Intake manifold charge air temperature sensor in­
put is monitored.
• Throttle position sensor (TPS) is monitored. • The auto shut down (ASD) relay is energized by
the PCM for approximately three seconds. • The fuel pump is energized through the fuel pump
relay by the PCM. The fuel pump will operate for ap­
proximately one second unless the engine is operat­ ing or the starter motor is engaged.
• The 02 sensor(s) heater element is energized
through the fuel pump relay. The 02 sensor(s) input

•

FUEL SYSTEM
14 - 39 is not used by the PCM to calibrate air-fuel ratio
during this mode of operation,
• The up-shift indicator light is illuminated (manual
transmission only).
ENGINE
START-UP
MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The powertrain control module (PCM) receives in­
puts from:
• Battery voltage
• Engine coolant temperature sensor • Crankshaft position sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Starter motor relay • Camshaft position sensor signal The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position sensor signal within 3 seconds of cranking the en­

gine,
it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the
PCM. The PCM will then control the injection se­ quence and injector pulse width by turning the
ground circuit to each individual injector on and off.
The PCM determines the proper ignition timing ac­
cording to input received from the crankshaft posi­
tion sensor.
ENGINE
WARM-UP
MODE This is an Open Loop mode. During engine warm-

up,
the powertrain control module (PCM) receives in­
puts from:
• Battery voltage • Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS) • Camshaft position sensor signal (in the distributor)
• Park/Neutral switch (gear indicator signal—auto,

trans,
only)
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped) Based on these inputs the following occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control the injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off.
• The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition tim­
ing. • The PCM operates the A/C compressor clutch
through the clutch relay. This is done if A/C has
been selected by the vehicle operator and requested by the A/C thermostat.
• If the vehicle has a manual transmission, the up­
shift light is operated by the PCM.
« When engine has reached operating temperature,
the PCM will begin monitoring 02 sensor(s) input.
The system will then leave the warm-up mode and go into closed loop operation.

IDLE
MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At idle speed, the powertrain control module (PCM) receives inputs from:
Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor • Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
® Battery voltage
• Park/Neutral switch (gear indicator signal—Auto,

trans,
only) • Oxygen sensor
Based on these inputs, the following occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off.
• The PCM monitors the 02 sensor(s) input and ad­
justs air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed through the idle air
control (IAC) motor. • The PCM adjusts ignition timing by increasing and decreasing spark advance.
• The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.

CRUISE
MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the power-
train control module (PCM) receives inputs from:
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage • Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)

14
- 40
FUEL
SYSTEM

• • Park/Neutral switch (gear indicator signal—auto,

trans,
only)
• Oxygen (02) sensor(s) Based on these inputs, the following occurs:
• Voltage is applied to the fuel injectors with the
PCM. The PCM will then adjust the injector pulse
width by turning the ground circuit to each individ­
ual injector on and off.
• The PCM monitors the 02 sensor(s) input and ad­
justs air-fuel ratio. It also adjusts engine idle speed through the idle air control (IAC) motor.
• The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
• The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.

ACCELERATION MODE
This is an Open Loop mode. The powertrain control
module (PCM) recognizes an abrupt increase in
throttle position or MAP pressure as a demand for
increased engine output and vehicle acceleration.
The PCM increases injector pulse width in response
to increased throttle opening.

DECELERATION MODE
When the engine is at operating temperature, this
is an Open Loop mode. During hard deceleration, the
powertrain control module (PCM) receives the follow­ ing inputs.
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
• Park/Neutral switch (gear indicator signal —auto,

trans,
only)
If the vehicle is under hard deceleration with the
proper rpm and closed throttle conditions, the PCM
will ignore the oxygen sensor input signal. The PCM
will enter a fuel cut-off strategy in which it will not supply battery voltage to the injectors. If a hard de­
celeration does not exist, the PCM will determine the
proper injector pulse width and continue injection.
Based on the above inputs, the PCM will adjust en­
gine idle speed through the idle air control (IAC) mo­
tor. The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
The PCM opens the ground circuit to the A/C
clutch relay to disengage the A/C compressor clutch.
This is done until the vehicle is no longer under de­
celeration (if the A/C system is operating).
WIDE OPEN
THROTTLE
MODE

This is an Open Loop mode. During wide open
throttle operation, the powertrain control module (PCM) receives the following inputs.
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS) • Camshaft position sensor signal (in the distributor) During wide open throttle conditions, the following
occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control the injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of additional fuel. This is done by adjusting
injector pulse width.
• The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
• The PCM opens the ground circuit to the A/C
clutch relay to disengage the A/C compressor clutch.
This will be done for approximately 15 seconds (if the air conditioning system is operating).
If the vehicle has a manual transmission, the up­
shift light is operated by the PCM.

IGNITION
SWITCH
OFF
MODE
When ignition switch is turned to OFF position,
the PCM stops operating the injectors, ignition coil,
ASD relay and fuel pump relay.

THROTTLE
BODY
Filtered air from the air cleaner enters the intake
manifold through the throttle body (Fig. 18). Fuel does not enter the intake manifold through the throt­
tle body. Fuel is sprayed into the manifold by the fuel injectors. The throttle body is mounted on the
intake manifold. It contains an air control passage (Fig. 19) controlled by an idle air control (IAC) mo­
tor. The air control passage is used to supply air for idle conditions. A throttle valve (plate) is used to supply air for above idle conditions. The throttle position sensor (TPS), idle air control
(IAC) motor and manifold absolute pressure sensor
(MAP) are attached to the throttle body. The acceler­
ator pedal cable, speed control cable and transmis­
sion control cable (when equipped) are connected to
the throttle arm. A (factory adjusted) set screw is used to mechani­
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are
controlled by the PCM.

MULTI-PORT
FUEL
INJECTION
(MPI)—GENERAL DIAGNOSIS—EXCEPT DIESEL

INDEX

page

Camshaft Position Sensor Testing
............
52
Charge
Air
Temperature Sensor Test
52

Coolant Temperature Sensor Test
52

Crankshaft Position Sensor Test
54

Diagnostic Trouble Code (DTC)
60

DRB
II
Scan
Tool
........................
60

Fuel
Injector
Test
57

Fuel Pump Pressure Test
57
Idle
Air
Control
(IAC) Motor Test
55

Manifold Absolute Pressure (MAP) Sensor Test
. 53
page

On-Board
Diagnostics (OBD)
59

Oxygen
(02)
Sensor Heating Element Test
54
Powertrain
Control
Module (PCM) 60-Way Connector
. 47

Relays—Operation/Testing
56

Starter
Motor Relay Test
57

System
Schematics
. 47

Throttle
Position Sensor (TPS) Test
54

Visual Inspection
43

VISUAL
INSPECTION
A visual inspection
for
loose, disconnected,
or
incor­
rectly routed wires
and
hoses should
be
made. This should
be
done before attempting
to
diagnose
or
ser­
vice
the
fuel injection system.
A
visual check will
help spot these faults
and
save unnecessary test
and
diagnostic time.
A
thorough visual inspection will
in­

clude
the
following checks: (1) Verify that
the
60-way connector
is
fully
in­

serted into
the
connector
of the
powertrain control
module
(PCM) (Fig. 1).
Verify that
the
connector
mounting screw
is
tightened
to 4 N#m (35 in. lbs.)
torque.
PCM
MOUNTING
BOLTS

PCM CONNECTOR CONNECTOR MOUNTING BOLT
J9314-165

Fig.
1
Powertrain Control
Module
(PCM) (2) Inspect
the
battery cable connections.
Be
sure
that they
are
clean
and
tight.
(3) Inspect fuel pump relay
and air
conditioning
compressor clutch relay
(if
equipped). Inspect
the

ASD relay connections. Inspect starter motor relay connections. Inspect relays
for
signs
of
physical dam­
age
and
corrosion.
The
relays
are
located
in the en­

gine compartment
(Fig. 2).
TORQUE CONVERTER
CLUTCH RELAY
A/C
CLUTCH RELAY STARTER RELAY
AUTO SHUTDOWN RELAY FUEL PUMP RELAY POWERTRAIN
DATA UNK CONTROL
CONNECTOR MODULE
J9314-164

Fig.
2
Relay Location (4) Inspect ignition coil connections. Verify that
coil secondary cable
is
firmly connected
to
coil (Fig.
3

or 4).
|X COIL

frCONNECTOR J9214-7

Fig.
3
Ignition Coil—3.9U5.2L/5.9L
LDC-Gas
Engine