air filter DODGE TRUCK 1993 Service Owner's Guide

FUEL
DELIVERY—DIESEL
ENGINE

INDEX

page

Fuel Gauge Sending Unit Module
15

General Information
15
Manual
Shut Down Lever
. . 17
page

Mechanical
Lift
Pump
15

Quick
Connect Fittings—Except
Chassis
Fuel Tubes
17

GENERAL
INFORMATION
The fuel system of the 5.9L turbo-diesel engine
consists of the:
• Fuel tank • Low and high pressure fuel supply lines
• Mechanical lift pump
• Fuel/water separator filter
• Fuel heater
• Fuel injection pump • Fuel injectors
• Fuel return lines For information regarding fuel requirements of the
5.9L turbo diesel engine, refer to the Fuel Require­
ments—Diesel Engines paragraph at the front of this group.

MECHANICAL
LIFT
PUMP
The mechanical lift pump is located on the left side
of the engine cylinder block. The lift pump is driven
by an eccentric on the camshaft that actuates a spring loaded lever in the pump (Fig. 1). The lever is
connected to the pump diaphragm. When the eccen­
tric on the camshaft pushes the lever upward, the le­ ver in turn pulls the diaphragm to its extended
position. Fuel is drawn into the pump chamber
through the inlet check valve. When the pump gath­ ers more fuel in the fuel chamber than the engine
can consume, the outlet check valve is held closed.
The fuel gathered in lift pump chamber prevents the diaphragm from relaxing. The lever will continue to
move up and down on the shaft connecting it to the
diaphragm. However, the lever is prevented from op­
erating the diaphragm until the check valve again
opens to expel fuel from the pump chamber. This pro­ cess continues as long as the engine is running.
Minimum lift pump output pressure is 21 Kpa (3

psi).
Lift pump output volume is 0.75 liters (0.70 U.S. quarts) per 30 seconds of engine cranking. The lift pump housing has a weep hole at the bot­
tom of the casing (Fig. 1). If the diaphragm ruptures,
fuel will exit out of the weep hole and the pump
must be replaced. The lift pump is not serviceable and must be replaced as a complete assembly.

CAUTION:
Do not
operate
the
engine
if the
fuel
sup­ply
line
has a
restriction
of
more than
95 MM Hg

(3.75
in Hg).
Fig.
1
Lift
Pump

The lift pump has a manual lever.(Fig. 2). The le­
ver is located on the lower right side of the pump
housing. The purpose of the lever is to prime the fuel system and bleed air from the system if the vehicle
has run out of fuel. To prime the system up to the injector pump, raise and lower the lever until resis­
tance is felt. During vehicle operation the pump le­
ver must be in the up position.
J9114-3
Fig.
2
Lift
Pump
Manual
Lever

FUEL GAUGE SENDING
UNIT
MODULE
The fuel gauge sending unit module is installed in
the top of the fuel tank (Fig. 3). The fuel gauge send­ ing unit module contains the following components (Fig. 4).

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.

•

FUEL
SYSTEM
14-45 (12) Inspect accelerator cable, transmission throt­
tle cable (if equipped) and cruise control cable con­
nections (if equipped). Check their connections to the
throttle arm of throttle body for any binding or re­ strictions (Fig. 8).

Fig.
8
Throttle
Body
Cables—Typical
(13) If equipped with vacuum brake booster, verify
that vacuum booster hose is firmly connected to fit­
ting on intake manifold. Also check connection to
brake vacuum booster.
(14) Inspect the air cleaner inlet and air filter ele­
ment for dirt or restrictions.
(15) Inspect radiator grille area, radiator fins and
air conditioning condenser for restrictions. (16) Verify that the intake manifold charge air
temperature sensor wire connector is firmly con­ nected to harness connector (Figs. 9 or 10).

Fig.
9 Air
Temperature
Sensor—3.9L
(V-6)
Engine
(17) Verify that MAP sensor electrical connector is
firmly connected to MAP sensor (Fig. 11). Also verify
that rubber L-shaped fitting from MAP sensor to the
throttle body is firmly connected (Fig. 12).
(18) Verify that fuel injector wire harness connec­
tors are firmly connected to injectors in the correct
Fig.
10 Air
Temperature
Sensor—5.2U5.9L
(V-8)

Engines
MANIFOLD
ABSOLUTE

Fig.
11 MAP Sensor—Typical
order. Each harness connector is numerically tagged
with the injector number (INJ 1, INJ 2 etc.) of its
corresponding fuel injector and cylinder number.
(19) Verify harness connectors are firmly con­
nected to idle air control (IAC) motor, throttle posi­
tion sensor (TPS) and manifold absolute pressure (MAP) sensor (Fig. 11).
(20) Verify that wire harness connector is firmly
connected to the engine coolant temperature sensor (Fig. 13).
(21) Raise and support the vehicle.
(22) Verify that oxygen sensor wire connector (or
connectors) are firmly connected to the sensor (or sensors). Inspect sensor(s) and connector(s) for dam­age (Figs. 14 or 15).

•

FUEL SYSTEM
14 - 59
fill
DHADn
HIAf5MflCTipQ
/f|Rn

The powertrain control module (PCM) has been
programmed to monitor many different circuits of the
fuel injection system. If a problem is sensed in a monitored circuit often enough to indicate an actual
problem, a diagnostic trouble code (DTC) is stored.
The DTC will be stored in the PCM memory for eventual display to the service technician. If the
problem is repaired or ceases to exist, the PCM can­ cels the DTC after 51 engine starts.
Certain criteria must be met for a diagnostic trou­
ble code (DTC) to be entered into PCM memory. The criteria may be a specific range of engine rpm, en­
gine temperature and/or input voltage to the PCM.
It is possible that a DTC for a monitored circuit
may not be entered into memory even though a mal­
function has occurred. This may happen because one
of the DTC criteria for the circuit has not been met. Example: assume that one of the criteria for the
MAP sensor circuit is that the engine must be oper­ ating between 750 and 2000 rpm to be monitored for
a DTC. If the MAP sensor output circuit shorts to
ground when the engine rpm is above 2400 rpm, a 0
volt input will be seen by the PCM. A DTC will not
be entered into memory because the condition does not occur within the specified rpm range.
A DTC indicates that the powertrain control mod­
ule (PCM) has recognized an abnormal signal in a
circuit or the system. A DTC may indicate the result
of a failure, but never identify the failed component
directly.
There are several operating conditions that the
PCM does not monitor and set a DTC for. Refer to
the following Monitored Circuits and Non-Monitored Circuits in this section.

MONITORED
CIRCUITS
The powertrain control module (PCM) can detect
certain problems in the fuel injection system.
Open or Shorted Circuit - The PCM can deter­
mine if sensor output (which is the input to PCM) is
within proper range. It also determines if the circuit is open or shorted.
Output Device Current Flow - The PCM senses
whether the output devices are hooked up.
If there is a problem with the circuit, the PCM
senses whether the circuit is open, shorted to ground
(-), or shorted to
(
+
)
voltage.
Oxygen Sensor - The PCM can determine if the
oxygen sensor is switching between rich and lean.
This is, once the system has entered Closed Loop. Re­ fer to Open Loop/Closed Loop Modes Of Operation in
the Component Description/System Operation section
for an explanation of Closed (or Open) Loop opera­ tion.
NON-MONITORED CIRCUITS

The PCM does not monitor the following circuits,
systems or conditions that could have malfunctions
that result in driveability problems. A diagnostic trouble code (DTC) may not be displayed for these
conditions.
Fuel Pressure: Fuel pressure is controlled by the
vacuum assisted fuel pressure regulator. The PCM
cannot detect a clogged fuel pump inlet filter, clogged
in-line fuel filter, or a pinched fuel supply or return

line.
However, these could result in a rich or lean
condition causing an oxygen sensor DTC to be stored in the PCM.
Secondary Ignition Circuit: The PCM cannot de­
tect an inoperative ignition coil, fouled or worn spark

plugs,
ignition cross firing, or open circuited spark
plug cables.
Engine Timing: The PCM cannot detect an incor­
rectly indexed timing chain, camshaft sprocket or crankshaft sprocket. The PCM also cannot detect an
incorrectly indexed distributor. However, these could
result in a rich or lean condition causing an oxygen
sensor DTC to be stored in the PCM.
Cylinder Compression: The PCM cannot detect
uneven, low, or high engine cylinder compression.
Exhaust System: The PCM cannot detect
a

plugged, restricted or leaking exhaust system.
Fuel Injector Malfunctions: The PCM cannot de­
termine if the fuel injector is clogged, or the wrong injector is installed. However, these could result in a
rich or lean condition causing an oxygen sensor DTC
to be stored in the PCM.
Excessive Oil Consumption: Although the PCM
monitors exhaust stream oxygen content through ox­
ygen sensor (closed loop), it cannot determine exces­ sive oil consumption.
Throttle Body Air Flow: The PCM cannot detect
a clogged or restricted air cleaner inlet or air filter
element.
Evaporative System: The PCM will not detect a
restricted, plugged or loaded EVAP canister. Vacuum Assist: Leaks or restrictions in the vac­
uum circuits of vacuum assisted engine control sys­
tem devices are not monitored by the PCM. However, a vacuum leak at the MAP sensor will be monitored
and a diagnostic trouble code (DTC) will be gener­
ated by the PCM.
Powertrain Control Module (PCM) System
Ground: The PCM cannot determine a poor system
ground. However, a DTC may be generated as a re­
sult of this condition.
Powertrain Control Module (PCM) Connector
Engagement: The PCM cannot determine spread or
damaged connector pins. However, a DTC may be generated as a result of this condition.

MULTI-PORT
FUEL
INJECTION
(MPI)-COMPONENT

REMOVAL/INSTALLATION
—EXCEPT DIESEL

INDEX

page

Accelerator Pedal
and Throttle
Cable
. 64

Air Conditioning (A/C) Clutch Relay
64
Air
Filter/Filter
Housing
64

Automatic Shut Down (ASD) Relay
. 64
Brake
Switch
64

Camshaft
Position
Sensor
..................
64

Charge
Air
Temperature
Sensor
64

Crankshaft Position
Sensor
64

Engine
Coolant Temperature
Sensor
65
EVAP
Canister Purge Solenoid
65

Fuel
Filter
65

Fuel Filter/Fuel Pressure Regulator—5.9L Engine
. 65

Fuel Injector(S)
67

Fuel Pressure Regulator
67

Fuel Pump Module
68

Fuel Pump Relay
68

ACCELERATOR
PEDAL
AND THROTTLE
CABLE
Refer
to
the
Accelerator Pedal
and
Throttle Cable
section
of
this group
for
removal/installation proce­

dures.

AIR
CONDITIONING (A/C) CLUTCH RELAY The A/C clutch relay
is
located
in
the
engine com­
partment (Fig.
1).

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

Fig.
1 Relay Location

AIR
FILTER/FILTER
HOUSING
Refer
to
Air Filter/Filter Housing—Gas Engines
in

Group
25,
Emission Control System
for
removal/in­
stallation procedures.
AUTOMATIC SHUT DOWN (ASD) RELAY The ASD relay
is
located
in
the
engine compart­
ment (Fig.
1).
page

Fuel Rail
69

Fuel System Pressure Release Procedure
......
71
Fuel Tank Pressure Relief/Rollover Valve
71

Fuel Tanks
71

Fuel
Tubes/Lines/Hoses
and
Clamps
71
Idle
Air
Control (IAC) Motor
71

Ignition Coil
71

Intake Manifold
71

Manifold Absolute Pressure (MAP)
Sensor
71

Oxygen
(02)
Sensor
72

Park/Neutral Switch
. 73

Powertrain Control Module (PCM)
73

Quick-Connect
Fittings
73

Throttle
Body
73
Throttle
Position
Sensor
(TPS)
......
74

Vehicle
Speed
Sensor
75

BRAKE
SWITCH
Refer
to
Group
5,
Brakes
for
removal/installation
procedures.

CAMSHAFT
POSITION
SENSOR
For removal/installation procedures, refer
to
Group

8D,
Ignition System. See Camshaft Position Sensor.

CHARGE
AIR
TEMPERATURE SENSOR
The intake manifold charge
air
temperature sensor
is located
in the
front/side
of
the
intake manifold (Fig.
2
or
3).

REMOVAL
(1) Remove
air
cleaner assembly.
(2) Disconnect electrical connector
at
sensor (Figs.
2
or
3). (3) Remove sensor from intake manifold.

INSTALLATION
(1) Install sensor
to
intake manifold. Tighten
to 28

Nnn (20
ft.
lbs.) torque.
(2) Install electrical connector.
(3) Install
air
cleaner.

CRANKSHAFT
POSITION
SENSOR
Refer
to
Group 8D, Ignition System
for
removal/in­
stallation procedures.

Fig. 2 Ait Temperature Sensor—3.9L (¥-6) Engine
Fig. 3 Air Temperature Sensor—5.2U5.9L (V-8)
Engines

ENGINE
COOLANT
TEMPERATURE
SENSOR

REMOVAL

WARNING:
HOT,
PRESSURIZED COOLANT
CAN
CAUSE
INJURY
BY
SCALDING- COOLING SYSTEM MUST
BE
PARTIALLY DRAINED BEFORE REMOV­
ING
THE
COOLANT TEMPERATURE
SENSOR.
RE­

FER
TO
GROUP
7,
COOLING.

(1) Partially drain cooling system. Refer to Group

7,
Cooling. (2) Disconnect electrical connector from sensor
(Fig. 4).
Engines with air conditioning: When removing
the connector from sensor, 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 sen­ sor. It is not equipped with a lock type tab.
(3) Remove sensor from intake manifold. Fig. 4 Coolant Temperature Sensor—Typical

INSTALLATION
(1) Install sensor.
(2) Tighten to 11 Nnn (8 ft. lbs.) torque.
(3) Connect electrical connector to sensor.
The sensor connector is symmetrical (not indexed).
It can be installed to the sensor in either direction. (4) Replace any lost engine coolant. Refer to Group

7,
Cooling System.

E¥AP
CANISTER
PURGE
SOLENOID
Refer to Group 25, Emission Control System for re­
moval/installation procedures.

FUEL
FILTER

3.9L/5.21.
ENGINE
The fuel filter on vehicles equipped with a 3.9L
(V-6) or a 5.2L (V-8) engine is mounted to the frame

rail.
Refer to the Fuel Delivery System section of this
group for removal/installation procedures.

5.91 ENGINE
On vehicles equipped with the 5.9L (V-8) engine,
the fuel filter and fuel pressure regulator are one combined part. Refer to the following Fuel Filter/
Fuel Pressure Regulator—5.9L Engine for removal and installation procedures.

FUEL
FILTER/FUEL
PRESSURE
REGULATOR—5JL

ENGINE

WARNING:
THE FUEL SYSTEM IS UNDER A
CON­
STANT
PRESSURE,
EVEN
WITH
ENGINE OFF. BE­
FORE
SERVICING THE FUEL FILTER/FUEL

PRESSURE
REGULATOR, THE FUEL SYSTEM
PRESSURE
MUST BE
RELEASED.

Refer to Fuel System Pressure Release in the Fuel
Delivery System section of this group.

14
- 68
FUEL
SYSTEM

•

SNAP
RING
SNAP
RING

PLIERS
VACUUM

LINE
PROTECTIVE CAP
FUEL

PRESSURE

REGULATOR,
FUEL RAIL
J9214-47

Fig. 12 Regulator Snap Ring—3.9L Engine (4) Using a pair of 90 degree snap-ring pliers, re­
move the snap-ring (Fig. 12) from pressure regulator.
A small hand held mirror will aid in removal of this snap-ring.
(5) Remove pressure regulator from fuel rail.

INSTALLATION—3.9L
ENGINE
(1) Install new O-ring seals to pressure regulator.
(2) Install pressure regulator to fuel rail. The vac­
uum nipple on the regulator must be pointed straight

up.

(3) Install snap-ring. Be sure snap-ring is seated.
(4) Install vacuum line to pressure regulator.
(5) Install air cleaner.
(6) Start engine and check for leaks.

REMOVAL-5.21
(¥-8) ENGINE The pressure regulator is located (mounted verti­
cally) in the fuel rail assembly near the dash panel (Fig. 13). It is Jield to the fuel rail with a clamp and
bolt (Fig. 14).
(1) Perform the fuel pressure release procedure.
(2) Remove the air cleaner.
(3) Remove the vacuum line from the pressure reg­
ulator. (4) Remove the clamp bolt and regulator retaining
clamp from fuel rail.
(5) Remove pressure regulator from fuel rail.

INSTALLATION—5.2L
ENGINE
(1) Install new O-ring seals to pressure regulator.
(2) Install pressure regulator to fuel rail. (3) Install retaining clamp and clamp bolt.
(4) Install vacuum line to pressure regulator.
(5) Install air cleaner.
(6) Start engine and check for leaks.

REMOVAL/INSTALLATION—iJL (V-8) ENGINE
On vehicles equipped with the 5.9L (V-8) engine,
the fuel filter and fuel pressure regulator are one
FUEL

PRESSURE

REGULATOR FUEL RAIL
CONNECTOR
HOSES
J9214-27

Fig. 13 Fuel Pressure Regulator—5.2L Engine
FUEL

PRESSURE

REGULATOR MOUNTING
BOLT REGULATOR
MOUNTING CLAMP
J9214-48

Fig. 14 Pressure Regulator Mounting—5.2L Engine combined part. Refer to Fuel Filter/Fuel Pressure
Regulator—5.9L Engine for removal and installation
procedures.

FUEL
PUMP
MODULE
Refer to the Fuel Delivery System section of this
group for removal/installation procedures.

FUEL
PUMP
RELAY
The Fuel Pump relay is located in the engine com­
partment (Fig. 1).

•

FUEL SYSTEM
14-71
FUEL SYSTEM PRESSURE RELEASE PROCEDURE

WARNING:
THE
FUEL
SYSTEM
IS
UNDER
A
CON­

STANT
PRESSURE
(EVEN
WITH
THE
ENGINE

TURNED
OFF).
BEFORE
SERVICING
THE
FUEL
PUMP,
FUEL
LINES
(TUBES),
FUEL
FILTER,
OR

FUEL
INJECTOR(S),
THE
FUEL
SYSTEM
PRESSURE

MUST
BE
RELEASED.

To release fuel pressure, refer to the Fuel Delivery
System section of this group. See Fuel System Pres­
sure Release Procedure.

FUEL TANKS
Refer to the Fuel Tank section of this group for re­
moval/installation procedures.

FUEL TANK
PRESSURE
RELIEF/ROLLOVER VALVE
Refer to the Fuel Tank section of this group for re­
moval/installation procedures.

FUEL
TUBES/LINES/HOSES
AND CLAMPS
Refer to Fuel Tubes/Lines/Hoses and Clamps in the
Fuel Delivery System section of this group for remov­ al/installation procedures. Also refer to Quick-Connect Fittings in the Fuel
Delivery System section of this group for removal/in­
stallation procedures.

IDLE
AIR
CONTROL
(IAC)
MOTOR
The IAC motor is located on the back of the throt­
tle body (Fig. 22).
MANIFOLD ABSOLUTE
Fig.
22
idle
Air Control Motor—Typical
REMOVAL

(1) Remove air cleaner assembly.
(2) Disconnect electrical connector from IAC motor.
(3) Remove two mounting bolts (screws) (Fig. 23).

J9214-23

Fig.
23
Mounting
Bolts
(Screws)—IAC
Motor
(4) Remove IAC motor from throttle body.

INSTALLATION
(1) Install IAC motor to throttle body.
(2) Install and tighten two mounting bolts (screws)
to 7 N»m (60 in. lbs.) torque.
(3) Install electrical connector.
(4) Install air cleaner assembly.

IGNITION COIL
Refer to Group 8D, Ignition Systems for removal/
installation procedures.

INTAKE MANIFOLD
Refer to Group 11, Exhaust System and Intake
Manifold for removal/installation procedures.

MANIFOLD ABSOLUTE
PRESSURE
(MAP)
SENSOR
The MAP sensor is located on the front of the
throttle body (Fig. 24). An L-shaped rubber fitting is
used to connect the MAP sensor to throttle body (Fig.
25).
REMOVAL
The throttle body must be removed from the intake
manifold for MAP sensor removal.
(1) Remove air cleaner assembly.
(2) Remove throttle body. Refer to Throttle Body
removal in this section.
(3) Remove two MAP sensor mounting bolts
(screws) (Fig. 24). (4) While removing MAP sensor, slide the vacuum
rubber L-shaped fitting (Fig. 25) from the throttle
body.
(5) Remove rubber L-shaped fitting from MAP sen­
sor.

DIESEL
FUEL
INJECTION—COMPONENT
DESCRIPTION/SYSTEM
OPERATION

NDEX

page

Air
Conditioning (A/C) Clutch
Relay-PCM
Output
. 81

Air
Conditioning (A/C)
Controls-PCM
Input
.... 77

Air
Intake Heater
Relays—PCM
Output
........ 81

Auto
Shut
Down
(ASD)
Relay-PCM
Output
.... 82
Automatic
Shut
Down
(ASD)
Sense-PCM
input
. 78
Battery
Voltage-PCM
Input
78

Brake
Switch—PCM
Input
....... 78

Charge
Air
Temperature
Sensor—PCM
Input
... 78
Engine
Speed
Sensor—PCM
Input
........... 78

Fuel
Drain Manifold
83

Fuel
Heater
83

Fuel
Injection
Pump
83

Fuel
Injectors
84

Fuel
Solenoid
84

Fuel/Water
Separator
Filter ................. 84

General
Information
76

Generator
Field-PCM
Output
. 81

High
Pressure
Fuel
Lines
85
Ignition
Sense—PCM
Input
78

KSB
Solenoid
....... 85

Malfunction Indicator
Lamp—PCM
Output
...... 82

Manual
Shut
Down
Lever
.................. 85

GENERAL
INFORMATION

The fuel system of the 5.9L (in-line six-cylinder)
turbo-diesel engine (Fig. 1) consists of the following components:
• Fuel tank
• Low and high pressure fuel supply lines
• Mechanical lift pump
• Fuel/water separator filter
• Fuel heater
• Fuel injection pump
• Fuel injectors • Fuel return lines For information regarding fuel requirements of the
5.9L turbo-diesel engine, refer to the Fuel Require­
ments—Diesel Engines paragraph at the front of this group. Although various components, relays and switches
are operated by the powertrain control module (PCM), the diesel fuel injection system (Fig. 1) is not
directly regulated by the PCM. Refer to the proceed­
ing Powertrain Control Module section for additional
information.

SYSTEM
DIAGNOSIS
The PCM tests many of its own input and output
circuits. If a diagnostic trouble code (DTC) is found in a major system, this information is stored in the
PCM memory. Refer to On-Board Diagnostics in the Diesel Fuel Injection—General Diagnosis section of
page

Mechanical
Lift
Pump
86

Overdrive
Indicator
Lamp—PCM
Output
....... 82

Overdrive
Solenoid-PCM
Output
............ 82

Overdrive/Override
Switch—PCM
Input
........ 79
Park/Neutral
Switch-PCM
Input
79

Power
Ground-PCM
Input
. 79
Powertrain Control Module
(PCM)
76

SCI
Receive-PCM
Input
. . 80

SCI
Transmit-PCM
Output
. . . 82

Sensor
Return-PCM
Input
................. 80

Signal
Ground-PCM
Input
. 80

Speed
Control-PCM
Input
80

Speed
Control-PCM
Output
82

System
Diagnosis
76

System
Operation
86

Tachometer-PCM
Output
82

Throttle
Position
Sensor
(TPS)-PCM
Input
80

Vehicle
Speed
Sensor-PCM
Input
80

Wait-To-Start
Lamp-PCM
Output
82

Water-ln-Fuel
Lamp-PCM
Output
83

Water-ln-Fuel
Sensor-PCM
input
80
this group for DTC information. The DRB II scan tool can be used to access the DTC messages stored in the PCM memory.

POWERTRAIN
CONTROL
MODULE
(PCM)
The powertrain control module (PCM) (Fig. 2) was
formerly referred to as the SBEC or engine control­ ler. The PCM is a pre-programmed, dual micropro­
cessor digital computer. The PCM is located in the engine compartment be­
hind the battery and under the left front fender (Fig.
2).
The PCM contains a voltage convertor, which con­
verts battery voltage to a regulated 8.0 volts. This is used to power the engine speed sensor. The PCM also
provides a 5 volt supply for the throttle position sen­sor (TPS). The TPS is not used if equipped with a
manual transmission.
Various sensors, switches and relays provide the
inputs necessary for operation of the PCM.
The PCM Inputs are from:

9
Air conditioning control switch
• Automatic shut down (ASD) sense circuit
• Battery voltage
• Brake light switch • Charge air temperature sensor ® Coolant temperature sensor (Auto, trans, only)
• Engine speed sensor
• Ignition
• Overdrive/override switch
• Park/neutral switch (Auto, trans, only)

•

FUEL
SYSTEM
14-77

FUEL FROM SUPPLY TANK

LIFT
PUMP
LOW
PRESSURE
SUPPLY LINE
FUEL/WATER SEPARATOR FILTER
4A. FUEL HEATER
4B. FUEL/WATER DRAIN VALVE
FUEL/WATER SEPARATOR FILTER
W.I.F. (WATER
IN
FUEL) SENSOR
CHARGE
AIR
TEMP. SENSOR
BLEED
SCREW
LOW
PRESSURE
SUPPLY LINE
INJECTION PUMP
TURBO BOOST CONTROL LINE POWERTRAIN CONTROL MODULE
FUEL DRAIN MANIFOLD
(RETURN FUEL
TO
TANK)
HIGH
PRESSURE
LINES
INJECTORS

KSB
SOLENOID
MANUAL SHUT DOWN LEVER
TDC TIMING
PIN

AIR TEMP. SWITCH
NOTE: #10 CONTROLS INTAKE HEATER,
KSB
VALVE, FUEL HEATER,
WIF
SENSOR
J9314-179

Fig.
1
Diesel
Fuel
System
Components

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.
2 PCM Location—Typical Power ground
SCI receive (DRB II connection)
Sensor return
Signal ground
Speed control switch
Throttle position sensor (Auto, trans, only)
Transmission thermo-switch (Auto, trans, only)
Vehicle speed sensor
Water-in-fuel sensor Based on these inputs, the PCM regulates various
engine and vehicle operations through different sys­
tem components. These are called PCM outputs.
PCM outputs are to the:
• A/C compressor clutch relay
• Air intake heater relays
• Generator field control
• ASD relay
• Malfunction indicator lamp
• Overdrive indicator lamp
• Overdrive solenoid
• SCI transmit
• Speed control functions
• Tachometer (if equipped)
• Water-in-fuel indicator lamp • Wait-to-start indicator lamp

AIR CONDITIONING
(A/C)
CONTROLS-PCM
INPUT
The A/C control system information applies to fac­
tory installed air conditioning units only.

A/C
REQUEST SIGNAL

Once A/C has been selected, the PCM receives the
A/C request signal from the evaporator switch. The input indicates that the evaporator temperature is in
the proper range for A/C application. The PCM uses this input to cycle the A/C compressor clutch (through the A/C relay).