
The crankshaft position sensor is located in the
transaxle housing, above the vehicle speed sensor
(Fig. 10). The bottom of the sensor is positioned next
to the drive plate.The distance between the bot-
tom of sensor and the drive plate is critical to
the operation of the system. When servicing the
crankshaft position sensor, refer to the appro-
priate Multi-Port Fuel Injection Service Proce-
dures section in this Group.
2.4L
The second crankshaft counterweight has
machined into it two sets of four timing reference
notches and a 60 degree signature notch (Fig. 11).
From the crankshaft position sensor input the PCM
determines engine speed and crankshaft angle (posi-
tion).
The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltagegoes low (less than 0.3 volts). When a notch aligns
with the sensor, voltage spikes high (5.0 volts). As a
group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.
If available, an oscilloscope can display the square
wave patterns of each voltage pulse. From the width
of the output voltage pulses, the PCM calculates
engine speed. The width of the pulses represent the
amount of time the output voltage stays high before
switching back to low. The period of time the sensor
output voltage stays high before switching back to
low is referred to as pulse width. The faster the
engine is operating, the smaller the pulse width on
the oscilloscope.
By counting the pulses and referencing the pulse
from the 60 degree signature notch, the PCM calcu-
lates crankshaft angle (position). In each group of
timing reference notches, the first notch represents
69 degrees before top dead center (BTDC). The sec-
ond notch represents 49 degrees BTDC. The third
notch represents 29 degrees. The last notch in each
set represents 9 degrees before top dead center
(TDC).
The timing reference notches are machined to a
uniform width representing 13.6 degrees of crank-
shaft rotation. From the voltage pulse width the
PCM tells the difference between the timing refer-
ence notches and the 60 degree signature notch. The
60 degree signature notch produces a longer pulse
width than the smaller timing reference notches. If
the camshaft position sensor input switches from
high to low when the 60 degree signature notch
passes under the crankshaft position sensor, the
PCM knows cylinder number one is the next cylinder
at TDC.
The crankshaft position sensor mounts to the
engine block behind the generator, just above the oil
filter (Fig. 12).
ENGINE COOLANT TEMPERATURE SENSORÐPCM
INPUT
The engine coolant temperature sensor is a vari-
able resistor with a range of -40ÉC to 129ÉC (-40ÉF to
265ÉF).
The engine coolant temperature sensor provides an
input voltage to the PCM. As coolant temperature
varies, the sensor resistance changes resulting in a
different input voltage to the PCM.
When the engine is cold, the PCM will demand
slightly richer air/fuel mixtures and higher idle
speeds until normal operating temperatures are
reached.
The engine coolant sensor is also used for cooling
fan control.
Fig. 10 Crankshaft Position Sensor LocationÐ3.0/
3.3/3.8L
Fig. 11 Timing Reference Notches
14 - 36 FUEL SYSTEMNS
DESCRIPTION AND OPERATION (Continued)

(brake, park/neutral, air conditioning). Deceleration
die out is also prevented by increasing airflow when
the throttle is closed quickly after a driving (speed)
condition.
DUTY CYCLE EVAP CANISTER PURGE
SOLENOIDÐPCM OUTPUT
The duty cycle EVAP purge solenoid regulates the
rate of vapor flow from the EVAP canister to the
throttle body. The PCM operates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged. The
PCM de-energizes the solenoid during open loop oper-
ation.
The engine enters closed loop operation after it
reaches a specified temperature and the time delay
ends. During closed loop operation, the PCM ener-
gizes and de-energizes the solenoid 5 or 10 times per
second, depending upon operating conditions. The
PCM varies the vapor flow rate by changing solenoid
pulse width. Pulse width is the amount of time the
solenoid energizes.
A rubber boot covers the duty cycle EVAP purge
solenoid. The solenoid attaches to a bracket mounted
to the right engine mount (Fig. 31). The top of the
solenoid has the word TOP on it. The solenoid will
not operate properly unless it is installed correctly.
PROPORTIONAL PURGE SOLENOID
All vehicles use a proportional purge solenoid. The
solenoid regulates the rate of vapor flow from theEVAP canister to the throttle body. The PCM oper-
ates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged.
The proportional purge solenoid operates at a fre-
quency of 200 hz and is controlled by an engine con-
troller circuit that senses the current being applied
to the proportional purge solenoid and then adjusts
that current to achieve the desired purge flow. The
proportional purge solenoid controls the purge rate of
fuel vapors from the vapor canister and fuel tank to
the engine intake manifold.
ELECTRONIC EGR TRANSDUCER SOLENOIDÐPCM
OUTPUT
The electronic EGR transducer contains an electri-
cally operated solenoid and a back-pressure trans-
ducer (Fig. 33) or (Fig. 34) or (Fig. 35). The PCM
operates the solenoid. The PCM determines when to
energize the solenoid. Exhaust system back-pressure
controls the transducer.
When the PCM energizes the solenoid, vacuum
does not reach the transducer. Vacuum flows to the
transducer when the PCM de-energizes the solenoid.
When exhaust system back-pressure becomes high
enough, it fully closes a bleed valve in the trans-
ducer. When the PCM de-energizes the solenoid and
back-pressure closes the transducer bleed valve, vac-
uum flows through the transducer to operate the
EGR valve.
De-energizing the solenoid, but not fully closing the
transducer bleed hole (because of low back-pressure),
varies the strength of vacuum applied to the EGR
valve. Varying the strength of the vacuum changes
the amount of EGR supplied to the engine. This pro-
Fig. 31 Duty Cycle EVAP Purge Solenoid
Fig. 32 Proportional Purge Solenoid
NSFUEL SYSTEM 14 - 43
DESCRIPTION AND OPERATION (Continued)

vides the correct amount of exhaust gas recirculation
for different operating conditions.
DATA LINK CONNECTORÐPCM OUTPUT
The data link connector provides the technician
with the means to connect the DRB scan tool to diag-
nosis the vehicle. The connector is located under the
dash (Fig. 36).
AUTOMATIC TRANSAXLE CONTROL MODULEÐ
PCM OUTPUT
The electronic automatic transaxle control module
and the PCM supply information to each other
through the CCD Bus. The information includes
engine speed and vehicle load. The PCM uses the
information when adjusting the fuel and ignition
strategy.
FUEL INJECTORSÐPCM OUTPUT
The fuel injectors are 12 ohm electrical solenoids
(Fig. 37). The injector contains a pintle that closes off
an orifice at the nozzle end. When electric current is
supplied to the injector, the armature and needle
move a short distance against a spring, allowing fuel
to flow out the orifice. Because the fuel is under high
pressure, a fine spray is developed in the shape of a
hollow cone. The spraying action atomizes the fuel,
adding it to the air entering the combustion chamber.
The injectors are positioned in the intake manifold.
Fig. 33 EGR SolenoidÐ3.3/3.8L
Fig. 34 EGR SolenoidÐ3.0L
Fig. 35 EGR SolenoidÐ2.4L
Fig. 36 Data Link Connector
14 - 44 FUEL SYSTEMNS
DESCRIPTION AND OPERATION (Continued)

(13) Ensure the harness connector is securely
attached to each fuel injector.
(14) Check the oil pressure sending unit electrical
connection (Fig. 69).
(15) Check hose connections at throttle body.
(16) Check throttle body electrical connections
(Fig. 70).
(17) Check PCV hose connections (Fig. 71).
(18) Check EGR system vacuum hose connections
(Fig. 72).
(19) Check EGR tube to intake plenum connec-
tions.
(20) Check power brake booster vacuum connec-
tions.
(21) Check engine harness to main harness electri-
cal connections.
(22) Check all electronic automatic transaxle elec-
trical connections (Fig. 73).(23) Inspect the Powertrain Control Module (PCM)
40-way electrical connectors for damage or spread
Fig. 69 Oil Pressure Sending Unit Electrical
Connection
Fig. 70 Throttle Body Electrical and Vacuum Hose
Connections
Fig. 71 Positive Crankcase Ventilation (PCV) System
Fig. 72 EGR System
Fig. 73 Electronic Automatic Transaxle Electrical
Connections
14 - 54 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)

INTAKE AIR TEMPERATURE SENSORÐ2.4L
The intake air temperature sensor threads into the
intake manifold plenum (Fig. 133).
REMOVAL
(1) Remove electrical connector from sensor.
(2) Remove sensor.
INSTALLATION
(1) Install sensor. Tighten sensor to 28 N´m (20 ft.
lbs.) torque.
(2) Attach electrical connector to sensor.
SPECIFICATIONS
TORQUE
DESCRIPTION TORQUE
Generator Brkt. to Intake Manifold BoltsÐ3.3/3.8L.54
N´m (40 ft. lbs.)
Coolant SensorÐ2.4L..........7N´m(62in.lbs.)
Coolant SensorÐ3.0L..........7N´m(62in.lbs.)
Coolant SensorÐ3.3/3.8L........7N´m(62in.lbs.)
Cly. Head to Intake Manifold
Strut BoltsÐ3.3/3.8L........54N´m(40ft.lbs.)
EGR Tube to Intake Manifold
Screws..................22N´m(200 in. lbs.)
Idle Air Control Motor..........2N´m(18in.lbs.)
Ignition Coil Fasteners.......12N´m(105 in. lbs.)
Intake Air Temperature Sensor . .28 N´m (20 ft. lbs.)
MAP SensorÐ2.4L............4N´m(35in.lbs.)
MAP SensorÐ3.0L............4N´m(35in.lbs.)
MAP SensorÐ3.3/3.8L..........4N´m(35in.lbs.)
Upstream O2S...............27N´m(20ft.lbs.)
Downstream O2S.............27N´m(20ft.lbs.)
Throttle Body Bolts..........26N´m(225 in. lbs.)
SPECIAL TOOLS
FUEL
Fig. 133 Intake Air Temperature Sensor
Extractor C±4334
Pressure Gauge Assembly C±4799±B
Fuel Pressure Test Adapter 6539
Spanner Wrench 6856
14 - 72 FUEL SYSTEMNS
REMOVAL AND INSTALLATION (Continued)

For periodic draining of water from the bowl, refer
to Fuel Filter/Water Separator Removal/Installation
in this group.
FUEL SHUTDOWN SOLENOID
The fuel shutdown solenoid is controlled and
operated by the PCM.
The fuel shutdown (shut-off) solenoid is used to
electrically shut off the diesel fuel supply to the high-
pressure fuel injection pump. The solenoid is
mounted to the rear of the injection pump (Fig. 4).
The solenoid controls starting and stopping of the
engine regardless of the position of the accelerator
pedal. When the ignition (key) switch is OFF, the
solenoid is shut off and fuel flow is not allowed to the
fuel injection pump. When the key is placed in the
ON or START positions, fuel supply is allowed at the
injection pump.
FUEL INJECTION PUMP
The fuel injection pump is a mechanical distribu-
tor±type, Bosch VP36 series (Fig. 5). A gear on the
end of the injection pump shaft meshes with the
drive gear at the front of engine. The pump is
mechanically timed, relative to the position of the
cam and crankshaft. The PCM can make adjust-
ments to the timing of the injection pump.
The injection pump contains the fuel shutdown
solenoid, fuel temperature sensor, control sleeve sen-
sor, fuel quantity actuator and the fuel timing sole-
noid (Fig. 5).In the electronically controlled injection pump, the
pump plunger works the same as the pump plunger
in a mechanically controlled injection pump, but the
amount of fuel and the time the fuel is injected is
controlled by the vehicle's PCM, instead of by a
mechanical governor assembly. A solenoid controlled
by the PCM is used in place of the mechanical gov-
ernor assembly, and it moves a control sleeve inside
the pump that regulates the amount of fuel being
injected. There is no mechanical connection between
the accelerator pedal and the electronically controlled
injection pump. Instead, a sensor connected to the
accelerator pedal sends a signal to the PCM that rep-
resents the actual position of the accelerator pedal.
The PCM uses this input, along with input from
other sensors to move the control sleeve to deliver
the appropriate amount of fuel. This system is known
as ªDrive-By-Wireº
The actual time that the fuel is delivered is very
important to the diesel combustion process. The PCM
monitors outputs from the engine speed sensor (fly-
wheel position in degrees), and the fuel injector sen-
sor (mechanical movement within the #1 cylinder
fuel injector). Outputs from the Accelerator Pedal
Position sensor, engine speed sensor (engine rpm)
and engine coolant temperature sensor are also used.
The PCM will then compare its set values to these
outputs to electrically adjust the amount of fuel tim-
ing (amount of advance) within the injection pump.
This is referred to as ªClosed Loopº operation. The
PCM monitors fuel timing by comparing its set value
to when the injector #1 opens. If the value is greater
than a preset value a fault will be set.
Fig. 4 Fuel Shutdown Solenoid and Overflow Valve
Location
Fig. 5 Fuel Injection Pump
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 5
DESCRIPTION AND OPERATION (Continued)

FUEL INJECTION SYSTEMÐ2.0L ENGINE
INDEX
page page
GENERAL INFORMATION
INTRODUCTIONÐ2.0L ENGINE............ 32
MODES OF OPERATIONÐ2.0L ENGINE..... 32
DESCRIPTION AND OPERATION
AIR CONDITIONING (A/C) RELAYÐPCM
OUTPUTÐ2.0L ENGINE................ 35
AIR CONDITIONING PRESSURE
TRANSDUCERÐPCM INPUTÐ
2.0L ENGINE......................... 33
AIR CONDITIONING SWITCH SENSEÐ
PCM INPUTÐ2.0L ENGINE.............. 33
AUTOMATIC SHUTDOWN (ASD) SENSEÐ
PCM INPUTÐ2.0L ENGINE.............. 33
AUTOMATIC SHUTDOWN RELAYÐ
PCM OUTPUTÐ2.0L ENGINE............ 35
BATTERY VOLTAGEÐPCM INPUTÐ
2.0L ENGINE......................... 33
CAMSHAFT POSITION SENSORÐ
PCM INPUTÐ2.0L ENGINE.............. 33
CRANKSHAFT POSITION SENSORÐ
PCM INPUTÐ2.0L ENGINE.............. 33
DATA LINK CONNECTORÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
ELECTRONIC EGR TRANSDUCERÐ
PCM OUTPUTÐ2.0L ENGINE............ 35
ENGINE COOLANT TEMPERATURE SENSORÐ
PCM INPUTÐ2.0L ENGINE.............. 33
FUEL INJECTORSÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
FUEL PUMP RELAYÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
GENERATOR FIELDÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
HEATED OXYGEN SENSORÐPCM INPUTÐ
2.0L ENGINE......................... 33
IDLE AIR CONTROL MOTORÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
IGNITION COILÐPCM OUTPUTÐ
2.0L ENGINE......................... 36KNOCK SENSORÐPCM INPUTÐ
2.0L ENGINE......................... 34
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMPÐPCM OUTPUTÐ2.0L ENGINE...... 36
MANIFOLD ABSOLUTE PRESSURE
(MAP SENSOR)ÐPCM INPUTÐ
2.0L ENGINE......................... 34
POWERTRAIN CONTROL MODULEÐ
2.0L ENGINE......................... 33
RADIATOR FAN CONTROL MODULEÐ
PCM OUTPUTÐ2.0L ENGINE............ 36
SPEED CONTROL SOLENOIDSÐ
PCM OUTPUTÐ2.0L ENGINE............ 36
SPEED CONTROLÐPCM INPUTÐ
2.0L ENGINE......................... 34
STARTER RELAYÐPCM OUTPUTÐ
2.0L ENGINE......................... 35
SYSTEM DIAGNOSISÐ2.0L ENGINE........ 33
TACHOMETERÐPCM OUTPUTÐ
2.0L ENGINE......................... 36
THROTTLE BODYÐ2.0L ENGINE.......... 36
THROTTLE POSITION SENSOR/ IDLE AIR
CONTROL MOTORÐPCM INPUTÐ
2.0L ENGINE......................... 35
DIAGNOSIS AND TESTING
ASD AND FUEL PUMP RELAYSÐ
2.0L ENGINE......................... 39
CAMSHAFT AND CRANKSHAFT
POSITION SENSOR................... 40
ENGINE COOLANT TEMPERATURE
SENSOR............................ 40
KNOCK SENSORÐ2.0L ENGINE........... 40
MANIFOLD ABSOLUTE PRESSURE
(MAP) SENSORÐ2.0L ENGINE........... 39
THROTTLE BODY MINIMUM AIR FLOW..... 41
THROTTLE POSITION SENSOR........... 40
VISUAL INSPECTIONÐSOHC............. 36
SPECIFICATIONS
TORQUE............................. 42
GENERAL INFORMATION
INTRODUCTIONÐ2.0L ENGINE
Refer to the Introduction for 2.4/3.0/3.3/3.8L
engines under General Information in the Fuel Injec-
tion System section of group 14 for more information.
MODES OF OPERATIONÐ2.0L ENGINE
Refer to the Modes of Operation for 2.4/3.0/3.3/3.8L
engines under General Information in the Fuel Injec-
tion System section of group 14 for more information.
14 - 32 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS

THROTTLE POSITION SENSOR/ IDLE AIR
CONTROL MOTORÐPCM INPUTÐ2.0L ENGINE
Refer to the Throttle Control and Idle Air Control
motor for the 2.4/3.0/3.3/3.8L engines under Descrip-
tion and Operation in the Fuel Injection System sec-
tion of group 14 for more information.
AIR CONDITIONING (A/C) RELAYÐPCM
OUTPUTÐ2.0L ENGINE
Refer to the Air Conditioning relay for 2.4/3.0/3.3/
3.8L engines under Description and Operation in the
Fuel Injection System section of group 14 for more
information.
GENERATOR FIELDÐPCM OUTPUTÐ2.0L ENGINE
Refer to Generator Field for 2.4/3.0/3.3/3.8L
engines under Description and Operation in the Fuel
Injection System section of group 14 for more infor-
mation.
AUTOMATIC SHUTDOWN RELAYÐPCM
OUTPUTÐ2.0L ENGINE
Refer to Automatic Shutdown Relay for 2.4/3.0/3.3/
3.8L engines under Description and Operation in the
Fuel Injection System section of group 14 for more
information.
FUEL PUMP RELAYÐPCM OUTPUTÐ2.0L ENGINE
Refer to the Fuel Pump Relay for 2.4/3.0/3.3/3.8L
engines under Description and Operation in the Fuel
Injection System section of group 14 for more infor-
mation.
STARTER RELAYÐPCM OUTPUTÐ2.0L ENGINE
Refer to the Starter Relay for 2.4/3.0/3.3/3.8L
engines under Description and Operation in the Fuel
Injection System section of group 14 for more infor-
mation.
IDLE AIR CONTROL MOTORÐPCM OUTPUTÐ2.0L
ENGINE
Refer to the Idle Air Control Motor for 2.4/3.0/3.3/
3.8L engines under Description and Operation in the
Fuel Injection System section of group 14 for more
information. Refer to (Fig. 8) for component location
ELECTRONIC EGR TRANSDUCERÐPCM
OUTPUTÐ2.0L ENGINE
Refer to the Electronic EGR Transducer for 2.4/3.0/
3.3/3.8L engines under Description and Operation in
the Fuel Injection System section of group 14 for
more information.
DATA LINK CONNECTORÐPCM OUTPUTÐ2.0L
ENGINE
Refer to the Data Link Connector for 2.4/3.0/3.3/
3.8L engines under Description and Operation in the
Fuel Injection System section of group 14 for more
information.
FUEL INJECTORSÐPCM OUTPUTÐ2.0L ENGINE
Refer to the Fuel Injectors for 2.4/3.0/3.3/3.8L
engines under Description and Operation in the Fuel
Injection System section of group 14 for more infor-
mation.
Fig. 8 Throttle Position Sensor/Idle Air Control
motorÐ2.0L engine
Fig. 9 Electronic EGR TransducerÐ2.0L engine
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 35
DESCRIPTION AND OPERATION (Continued)