1996 CHRYSLER VOYAGER coolant temperature

²Engine coolant temperature
²Engine speed (crankshaft position sensor)
²Intake air temperature (2.4L only)
²Manifold absolute pressure
²Throttle position
²Transaxle gear selection (park/neutral switch)
The PCM also adjusts engine idle speed through
the idle air control motor based on the following
inputs.
²Air conditioning select switch head pressure
²Brake switch
²Engine coolant temperature
²Engine speed (crankshaft position sensor)
²Manifold absolute pressure
²Throttle position
²Transaxle gear selection (park/neutral switch)
²Vehicle distance (speed)
The Automatic Shutdown (ASD) and fuel pump
relays are located in the Power Distribution Center
(PDC).
The camshaft position sensor (distributor pick-up
signal 3.0L) and crankshaft position sensor signals
are sent to the PCM. If the PCM does not receive
both signals within approximately one second of
engine cranking, it deactivates the ASD relay and
fuel pump relay. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coil,
oxygen sensor heating element and fuel pump.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts to
power the camshaft position sensor, crankshaft posi-
tion sensor and vehicle speed sensor. The PCM also
provides a 5.0 volt supply for the manifold absolute
pressure sensor, throttle position sensor and engine
coolant temperature sensor.
AIR CONDITIONING PRESSURE TRANSDUCERÐ
PCM INPUT
The Powertrain Control Module (PCM) monitors
the A/C compressor discharge (high side) pressure
through the air conditioning pressure transducer.
The transducer supplies an input to the PCM. The
PCM engages the A/C compressor clutch if pressure
is sufficient for A/C system operation.
AIR CONDITIONING SWITCH SENSEÐPCM INPUT
When the air conditioning or defrost switch is put
in the ON position and the low pressure switch, com-
bination valve, and high pressure switch close, the
PCM receives an A/C input. After receiving this
input, the PCM activates the A/C compressor clutch
by grounding the A/C clutch relay. The PCM also
adjusts idle speed to a scheduled RPM to compensate
for increased engine load.
AUTOMATIC SHUTDOWN (ASD) SENSEÐPCM
INPUT
The ASD sense circuit informs the PCM when the
ASD relay energizes. A 12 volt signal at this input
indicates to the PCM that the ASD has been acti-
vated. This input is used only to sense that the ASD
relay is energized.
When energized, the ASD relay supplies battery
voltage to the fuel injectors, ignition coils and the
heating element in each oxygen sensor. If the PCM
does not receive 12 volts from this input after
grounding the ASD relay, it sets a Diagnostic Trouble
Code (DTC).
BATTERY VOLTAGEÐPCM INPUT
The PCM monitors the battery voltage input to
determine fuel injector pulse width and generator
field control.
If battery voltage is low the PCM will increase
injector pulse width (period of time that the injector
is energized).
BRAKE SWITCHÐPCM INPUT
When the brake switch is activated, the PCM
receives an input indicating that the brakes are
being applied. After receiving this input the PCM
maintains idle speed to a scheduled RPM through
control of the idle air control motor. The brake switch
is mounted on the brake pedal support bracket.
CAMSHAFT POSITION SENSORÐPCM INPUT
The PCM determines fuel injection synchronization
and cylinder identification from inputs provided by
the camshaft position sensor and crankshaft position
sensor. From the two inputs, the PCM determines
crankshaft position.
3.3/3.8L
The sensor generates pulses as groups of notches
on the camshaft sprocket pass underneath it (Fig. 2).
The PCM keeps track of crankshaft rotation and
identifies each cylinder by the pulses generated by
the notches on the camshaft sprocket. Four crank-
shaft pulses follow each group of camshaft pulses.
When the PCM receives two camshaft pulses fol-
lowed by the long flat spot on the camshaft sprocket,
it knows that the crankshaft timing marks for cylin-
der one are next (on driveplate). When the PCM
receives one camshaft pulse after the long flat spot
on the sprocket, cylinder number two crankshaft tim-
ing marks are next. After 3 camshaft pulses, the
PCM knows cylinder four crankshaft timing marks
follow. One camshaft pulse after the three pulses
indicates cylinder five. The two camshaft pulses after
cylinder 5 signals cylinder six (Fig. 3). The PCM can
synchronize on cylinders 1 or 4.
NSFUEL SYSTEM 14 - 33
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)

Shutdown (ASD) RelayÐPCM Output in this section
for relay operation.
TORQUE CONVERTER CLUTCH SOLENOIDÐPCM
OUTPUT
Three-speed automatic transaxles use a torque con-
verter clutch solenoid. The PCM controls the engage-
ment of the torque converter clutch through the
solenoid. The torque converter clutch is engaged only
in direct drive mode. Refer to Group 21 for transaxle
information.
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMPÐPCM OUTPUT
The PCM supplies the malfunction indicator (check
engine) lamp on/off signal to the instrument panel
through the CCD Bus. The CCD Bus is a communi-
cations port. Various modules use the CCD Bus to
exchange information.
The Check Engine lamp comes on each time the
ignition key is turned ON and stays on for 3 seconds
as a bulb test.
The Malfunction Indicator Lamp (MIL) stays on
continuously, when the PCM has entered a Limp-In
mode or identified a failed emission component. Dur-
ing Limp-in Mode, the PCM attempts to keep the
system operational. The MIL signals the need for
immediate service. In limp-in mode, the PCM com-
pensates for the failure of certain components that
send incorrect signals. The PCM substitutes for the
incorrect signals with inputs from other sensors.
If the PCM detects active engine misfire severe
enough to cause catalyst damage, it flashes the MIL.
At the same time the PCM also sets a Diagnostic
Trouble Code (DTC).
For signals that can trigger the MIL (Check
Engine Lamp) refer to Group 25, On-Board
Dianostics.
SOLID STATE FAN RELAYÐPCM OUTPUT
The radiator fan runs at a variable speed depend-
ing on coolant temperature and A/C system pressure.
The radiator fan circuit contains a Solid State Fan
Relay (SSFR). Refer to the Group 8W for a circuit
schematic.
A 5 volt signal is supplied to the SSFR. The PCM
provides a pulsed ground for the SSFR. Depending
upon the amount of pulse on time, the SSFR puts out
a proportional voltage to the fan motor at the lower
speed. For instance, if the on time is 30 percent, then
the voltage to the fan motor will be 3.6 volts.
When engine coolant reaches approximately 102ÉC
(215ÉF) the PCM grounds the SSFR relay. If engine
coolant reaches 207ÉC (225ÉF) the PCM grounds the
high speed ground relay and high speed fan relay. If
the fan operates at high speed, the PCM de-energizes
the high speed relay and high speed ground relay
when coolant temperature drops to approximately
101ÉC (214ÉF). When coolant temperature drops to
101ÉC (214ÉF) the fan operates at low speed. The
PCM de-energizes the low speed relay when coolant
temperature drops to approximately 93ÉC (199ÉF).
Also, when the air conditioning pressure switch
closes, the fan operates at high speed. The air condi-
tioning switch closes at 285 psi610 psi. When air
conditioning pressure drops approximately 40 psi, the
pressure switch opens and the fan operates at low
speed.
The SSFR relay is located on the left front inner
frame just behind the radiator (Fig. 42).
SPEED CONTROL SOLENOIDSÐPCM OUTPUT
The speed control vacuum and vent solenoids are
operated by the PCM. When the PCM supplies a
ground to the vacuum and vent solenoids, the speed
control system opens the throttle plate. When the
PCM removes the ground from the vacuum and vent
solenoids, the throttle blade closes. The PCM bal-
Fig. 41 Ignition Coil Ð3.3/3.8L
Fig. 42 Fan Control Module
14 - 46 FUEL SYSTEMNS
DESCRIPTION AND OPERATION (Continued)

(8) Verify the electrical connector is attached to
the Proportional purge solenoid (Fig. 50) and not
damaged.
(9) Verify the vacuum connection at the Propor-
tional purge solenoid is secure and not leaking.
(10) Verify the hoses are securely attached to the
EVAP canister (Fig. 51).(11) Ensure the harness connectors for the fuel
injectors are attached to the correct injector and not
damaged.
(12) Verify the fuel injector harness and engine
wiring harness connectors are fully inserted into the
main wiring harness.
(13) Check the vacuum connections at the throttle
body and intake plenum.
Fig. 48 Engine Coolant Temperature Sensor
Fig. 49 Knock Sensor
Fig. 50 Proportional Purge Solenoid
Fig. 51 Evaporative Canister
NSFUEL SYSTEM 14 - 49
DIAGNOSIS AND TESTING (Continued)

(5) Verify that the electrical connector is attached
to the MAP sensor (Fig. 64).
(6) Check generator wiring connections. Ensure
the accessory drive belt has proper tension.
(7) Verify that hoses are securely attached to the
evaporative canister (Fig. 65).
(8) Verify the engine ground strap is attached at
the engine and dash panel (Fig. 66).
(9) Ensure the heated oxygen sensor connector is
connected to the harness connector.
(10) Verify the distributor connector is connected
to the harness connector (Fig. 67).
(11) Verify the coolant temperature sensor connec-
tor is connected to the harness connector (Fig. 68).(12) Check vacuum hose connection at fuel pres-
sure regulator and intake plenum connector (Fig. 68).
Fig. 64 Map Sensor Electrical and Vacuum
Connections
Fig. 65 Evaporative Canister
Fig. 66 Engine Ground Strap
Fig. 67 Distributor Connector
Fig. 68 Coolant Temperature Sensor Electrical
Connections and Vacuum Hose Connections at the
Air Intake Plenum
NSFUEL SYSTEM 14 - 53
DIAGNOSIS AND TESTING (Continued)

(7) Verify the electrical connector at the knock sen-
sor is fully seated and not damaged (Fig. 78).
(8) Verify the electrical connector is attached to
the Proportional purge solenoid (Fig. 79) and not
damaged.
(9) Verify the vacuum connection at the Propor-
tional purge solenoid is secure and not leaking (Fig.
79).(10) Verify the hoses are securely attached to the
EVAP canister (Fig. 80).
(11) Ensure the harness connectors for the fuel
injectors are attached to the correct injector and not
damaged.
(12) Verify the fuel injector harness and engine
wiring harness connectors are fully inserted into the
main wiring harness.
Fig. 77 Engine Coolant Temperature Sensor
Fig. 78 Knock Sensor and Oil Pressure Sending
Unit Electrical Connection
Fig. 79 Proportional Purge Solenoid
Fig. 80 Evaporative Canister
14 - 56 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)

PCM. If OK, replace MAP sensor. If not OK, repair or
replace the wire harness as required.
HEATED OXYGEN SENSOR
Use an ohmmeter to test the heating element of
the oxygen sensors. Disconnect the electrical connec-
tor from each oxygen sensor. The white wires in the
sensor connector are the power and ground circuits
for the heater. Connect the ohmmeter test leads to
terminals of the white wires in the heated oxygen
sensor connector. Replace the heated oxygen sensor if
the resistance is not between 4 and 7 ohms.
KNOCK SENSOR
The engine knock sensor is affected by a number of
factors. A few of these are: ignition timing, cylinder
pressure, fuel octane, etc. The knock sensor gener-
ates an AC voltage whose amplitude increases with
the increase of engine knock. The knock sensor can
be tested with a digital voltmeter. The RMS voltage
starts at about 20mVac (at about 700 rpm) and
increases to approximately 600 mVac (5000 rpm). If
the output falls outside of this range a DTC will be
set.
CAMSHAFT AND CRANKSHAFT POSITION SENSOR
Refer to Group 8D, Ignition for Diagnosis and Test-
ing of Camshaft and Crankshaft Sensors.
ENGINE COOLANT TEMPERATURE SENSOR
(1) With the key off, disconnect wire harness con-
nector from coolant temperature sensor (Fig. 96) or
(Fig. 97) or (Fig. 98).
(2) Connect a high input impedance (digital) volt-
ohmmeter to terminals A and B (Fig. 99). The ohm-
meter should read as follows:
(a) ECT STET at normal operating temperature
around 200ÉF should read approximately 700 to
1,000 ohms.
(b) ECT STET at room temperature around 70ÉF
ohmmeter should read approximately 7,000 to
13,000 ohms.
(3) Test the resistance of the wire harness between
the PCM connector terminal 26 and the sensor har-
ness connector. Also check for continuity between
PCM connector terminal 43 and the sensor harness
connector. Refer to Group 8W, Wiring diagrams for
Fig. 96 Engine Coolant Temperature SensorÐ2.4L
Fig. 97 Engine Coolant Temperature SensorÐ3.0L
Fig. 98 Engine Coolant Temperature SensorÐ3.3/
3.8L
NSFUEL SYSTEM 14 - 61
DIAGNOSIS AND TESTING (Continued)