1996 CHRYSLER VOYAGER engine

CRANKSHAFT POSITION SENSORÐPCM INPUT
3.0/3.3/3.8L
The crankshaft position sensor (Fig. 8) senses slots
cut into the transaxle driveplate extension. There are
3 sets of slots. Each set contains 4 slots, for a total of
12 slots (Fig. 9). Basic timing is set by the position of
the last slot in each group. Once the PCM senses the
last slot, it determines crankshaft position (which
piston will next be at TDC) from the camshaft posi-
tion sensor input. It may take the PCM one engine
revolution to determine crankshaft position.
The PCM uses the crankshaft position sensor sig-
nal to determine injector sequence, ignition timing
and presence of misfire. Once crankshaft position has
been determined, the PCM begins energizing the
injectors in sequence.
Fig. 5 Camshaft Position Sensor
Fig. 6 Target Magnet
Fig. 7 Target Magnet Polarity
Fig. 8 Crankshaft Position Sensor
Fig. 9 Timing Slots
NSFUEL SYSTEM 14 - 35
DESCRIPTION AND OPERATION (Continued)

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)

3.0/3.3/3.8L
The sensor is installed next to the thermostat
housing (Fig. 13) and (Fig. 14).
2.4L
The coolant sensor threads into the top of the ther-
mostat housing (Fig. 15). New sensors have sealant
applied to the threads.
HEATED OXYGEN SENSOR (O2S SENSOR)ÐPCM
INPUT
The O2S produce voltages from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air/fuel mixture), the
sensors produces a low voltage. When there is a
lesser amount present (rich air/fuel mixture) it pro-
duces a higher voltage. By monitoring the oxygen
content and converting it to electrical voltage, the
sensors act as a rich- lean switch.
The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
Fig. 12 Crankshaft Position SensorÐ2.4L
Fig. 13 Engine Coolant Temperature SensorÐ3.3/
3.8L
Fig. 14 Engine Coolant Temperature SensorÐ3.0L
Fig. 15 Engine Coolant Temperature SensorÐ2.4L
NSFUEL SYSTEM 14 - 37
DESCRIPTION AND OPERATION (Continued)

system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the
O2S input (along with other inputs) and adjusts the
injector pulse width accordingly. During Open Loop
operation the PCM ignores the O2 sensor input. The
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature.
UPSTREAM HEATED OXYGEN SENSOR
The upstream O2S is located in the exhaust mani-
fold and provides an input voltage to the PCM. The
input tells the PCM the oxygen content of the
exhaust gas (Fig. 16) or (Fig. 17) or (Fig. 18). The
PCM uses this information to fine tune the air/fuel
ratio by adjusting injector pulse width.
DOWNSTREAM HEATED OXYGEN SENSOR
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 19). The downstream heated oxygen sensor
input is used to detect catalytic convertor deteriora-
tion. As the convertor deteriorates, the input from
the downstream sensor begins to match the upstream
sensor input except for a slight time delay. By com-
paring the downstream heated oxygen sensor input
to the input from the upstream sensor, the PCM cal-
culates catalytic convertor efficiency.When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the Malfunction Indica-
tor Lamp (MIL). For more information, refer to
Group 25 - Emission Control Systems.
KNOCK SENSORÐPCM INPUT
The knock sensor is only on the 2.4/3.3/3.8L
engines, not used on the 3.0L engine.
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 20) or (Fig.
21). When the knock sensor detects a knock in one of
the cylinders, it sends an input signal to the PCM. In
response, the PCM retards ignition timing for all cyl-
inders by a scheduled amount.
Knock sensors contain a piezoelectric material
which sends an input voltage (signal) to the PCM. As
the intensity of the engine knock vibration increases,
the knock sensor output voltage also increases.
Fig. 16 Heated Oxygen SensorÐ2.4L Engine
Fig. 17 Heated Oxygen SensorÐ3.0L Engine
Fig. 18 Heated Oxygen SensorÐ3.3/3.8L Engine
14 - 38 FUEL SYSTEMNS
DESCRIPTION AND OPERATION (Continued)

MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐPCM INPUT
The PCM supplies 5 volts to the MAP sensor. The
MAP sensor converts intake manifold pressure into
voltage. The PCM monitors the MAP sensor output
voltage. As vacuum increases, MAP sensor voltage
decreases proportionately. Also, as vacuum decreases,
MAP sensor voltage increases proportionately.
During cranking, before the engine starts running,
the PCM determines atmospheric air pressure from
the MAP sensor voltage. While the engine operates,
the PCM determines intake manifold pressure from
the MAP sensor voltage.Based on MAP sensor voltage and inputs from
other sensors, the PCM adjusts spark advance and
the air/fuel mixture.
The MAP sensor (Fig. 22) or (Fig. 23) or (Fig. 24)
mounts to the intake manifold near the throttle body
inlet to the manifold. The sensor connects electrically
to the PCM.
SPEED CONTROLÐPCM INPUT
The speed control system provides five separate
voltages (inputs) to the Powertrain Control Module
(PCM). The voltages correspond to the ON/OFF, SET,
RESUME and CANCEL.
The speed control ON voltage informs the PCM
that the speed control system has been activated.
The speed control SET voltage informs the PCM that
Fig. 19 Downstream Heated Oxygen Sensor
Fig. 20 Knock SensorÐ3.3/3.8L Engines
Fig. 21 Knock SensorÐ2.4L Engine
Fig. 22 MAP SensorÐ3.3/3.8L
NSFUEL SYSTEM 14 - 39
DESCRIPTION AND OPERATION (Continued)

The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The TPS
output voltage to the PCM varies from approximately
0.5 volt at minimum throttle opening (idle) to 4 volts
at wide open throttle. Along with inputs from other
sensors, the PCM uses the TPS input to determine
current engine operating conditions and adjust fuel
injector pulse width and ignition timing.
VEHICLE SPEED AND DISTANCEÐPCM INPUT
The transaxle output speed sensor supplies the
vehicle speed and distance inputs to the PCM. The
output speed sensor is located on the side of the tran-
saxle (Fig. 25).The speed and distance signals, along with a closed
throttle signal from the TPS, determine if a closed
throttle deceleration or normal idle condition (vehicle
stopped) exists. Under deceleration conditions, the
PCM adjusts the idle air control motor to maintain a
desired MAP value. Under idle conditions, the PCM
adjusts the idle air control motor to maintain a
desired engine speed.
INTAKE AIR TEMPERATURE SENSORÐPCM INPUT
(2.4L ONLY)
The Intake Air Temperature (IAT) sensor measures
the temperature of the intake air as it enters the
engine. The sensor supplies one of the inputs the
PCM uses to determine injector pulse width and
spark advance.
The IAT sensor threads into the intake manifold
(Fig. 29).
AIR CONDITIONING (A/C) CLUTCH RELAYÐPCM
OUTPUT
The PCM operates the air conditioning clutch relay
ground circuit. The radiator fan control module sup-
plies battery power to the solenoid side of the relay.
The air conditioning clutch relay will not energize
unless the radiator fan control module energizes. The
radiator control module energizes when the air con-
ditioning or defrost switch is put in the ON position
and the low pressure switch, combination valve, and
high pressure switch close.
With the engine operating, the PCM cycles the air
conditioning clutch on and off when the A/C switch
closes with the blower motor switch in the On posi-
tion. When the PCM senses low idle speeds or wide-
open-throttle through the throttle position sensor, it
de-energizes the A/C clutch relay. The relay contacts
open, preventing air conditioning clutch engagement.
The air conditioning clutch relay is located in the
Power Distribution Center (PDC). The PDC is located
Fig. 27 Throttle Position SensorÐ3.0L
Fig. 28 Throttle Position SensorÐ2.4L
Fig. 29 Intake Air Temperature Sensor
NSFUEL SYSTEM 14 - 41
DESCRIPTION AND OPERATION (Continued)

in the engine compartment next to the battery (Fig.
30). A label affixed to the underside of the PDC cover
identifies the relays and fuses in the PDC.
GENERATOR FIELDÐPCM OUTPUT
The PCM regulates the charging system voltage
within a range of 12.9 to 15.0 volts. Refer to Group
8A for Battery system information and 8C for charg-
ing system information.
AUTOMATIC SHUTDOWN RELAYÐPCM OUTPUT
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to the fuel injectors, electronic ignition
coil and the heating elements in the oxygen sensors.
A buss bar in the Power Distribution Center (PDC)
supplies voltage to the solenoid side and contact side
of the relay. The ASD relay power circuit contains a
25 amp fuse between the buss bar in the PDC and
the relay. The fuse is located in the PDC. Refer to
Group 8W, Wiring Diagrams for circuit information.
The PCM controls the relay by switching the
ground path for the solenoid side of the relay on and
off. The PCM turns the ground path off when the
ignition switch is in the Off position unless the 02
Heater Monitor test is being run. Refer to Group 25,
On-Board Diagnostics. When the ignition switch is in
the On or Crank position, the PCM monitors the
crankshaft position sensor and camshaft position sen-
sor signals to determine engine speed and ignition
timing (coil dwell). If the PCM does not receive the
crankshaft position sensor and camshaft position sen-
sor signals when the ignition switch is in the Run
position, it will de-energize the ASD relay.The ASD relay is located in the PDC (Fig. 30). A
label affixed to the underside of the PDC cover iden-
tifies the relays and fuses in the PDC.
FUEL PUMP RELAYÐPCM OUTPUT
The fuel pump relay supplies battery voltage to the
fuel pump. The fuel pump relay power circuit con-
tains a 9 amp fuse. The fuse is located in the PDC.
Refer to Group 8W, Wiring Diagrams for circuit infor-
mation.
The PCM controls the fuel pump relay by switch-
ing the ground path for the solenoid side of the relay
on and off. The PCM turns the ground path off when
the ignition switch is in the Off position. When the
ignition switch is in the On position, the PCM ener-
gizes the fuel pump. If the crankshaft position sensor
does not detect engine rotation, the PCM de-ener-
gizes the relay after approximately one second.
The fuel pump relay is located in the PDC (Fig.
30). A label affixed to the underside of the PDC cover
identifies the relays and fuses in the PDC.
STARTER RELAYÐPCM OUTPUT
Double Start Override ia a feature that prevents
the starter from operating if the engine is already
running. This feature is accomplished with software
only. There was no hardware added because of this
feature. To incorporate the unique feature of Double
Start Override, it was necessary to use the PCM
(software) to control the starter circuit. To use the
PCM it was necessary to separate the starter relay
coil ground from the park neutral switch. The starter
relay ground is now controlled through Pin 60 of the
PCM. This allows the PCM to interrupt the ground
circuit if other inputs tell it that the engine is turn-
ing. If the starter system is operating properly, it can
be assumed that the override protection is also work-
ing.
IDLE AIR CONTROL MOTORÐPCM OUTPUT
The idle air control motor is mounted on the throt-
tle body. The PCM operates the idle air control motor
(Fig. 26) or (Fig. 27) or (Fig. 28). The PCM adjusts
engine idle speed through the idle air control motor
to compensate for engine load or ambient conditions.
The throttle body has an air bypass passage that
provides air for the engine at idle (the throttle blade
is closed). The idle air control motor pintle protrudes
into the air bypass passage and regulates air flow
through it.
The PCM adjusts engine idle speed by moving the
idle air control motor pintle in and out of the bypass
passage. The adjustments are based on inputs the
PCM receives. The inputs are from the throttle posi-
tion sensor, crankshaft position sensor, coolant tem-
perature sensor, and various switch operations
Fig. 30 Power Distribution Center (PDC)
14 - 42 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)