2001 CHRYSLER VOYAGER change time

lock the front wheels first. Any torque transfer from
the rear axle to the front axle disturbs the ABS/brak-
ing system and causes potential instabilities on a
slippery surface. The BOC de-couples the rear driv-
eline as soon the rear wheels begin to spin faster
than the front wheels (front wheels locked) in order
to provide increased braking stability. Furthermore
the BOC also reduces the likelihood of throttle off
over-steer during cornering. In a throttle off maneu-
ver, the BOC once again de-couples the rear driveline
forcing all the engine brake torque to the front
wheels. This eliminates the chance of lateral slip on
the rear axle and increases it on the front. The vehi-
cle will therefore tend to understeer, a situation
which is considered easier to manage in most circum-
stances. During this maneuver, and during the ABS
braking event, the BOC does not transmit torque
through to the rear wheels. The rear driveline mod-
ule, with the BOC, will perform the same as a front
wheel drive vehicle during these events. The gear
ratio offset between the front and rear differentials
force the BOC into the overrunning mode most of the
time. This allows BOC to significantly reduce the
rolling resistance of the vehicle, which improves fuel
consumption, allows the downsizing of the driveline
components, and prevents the PTU and propshaft
joints from overheating.
OPERATION
In order to achieve all-wheel drive operation in
reverse, the overrunning clutch locking functional
direction must be reversible. The bi-directional over-
running clutch (BOC) changes the operational mode
direction depending on the propeller shaft direction.
The propeller shaft rotates in the clockwise (when
viewed from the front) direction when the vehicle is
moving forward, which indexes the BOC to the for-
ward overrunning position. When the vehicle is in
reverse, the propeller shaft will rotate counter-clock-
wise and index the BOC to the reverse overrunning
position.
The BOC acts as a mechanical stator. It is active
(transmitting torque), or it is not active and in over-
running mode (not transmitting torque). This ªall or
nothingº approach to torque transfer would cause a
sudden application of all available power to the rear
wheels, which is not desirable. Therefore it is run in
series with a viscous coupler to smooth, dampen, and
limit the transmission of torque to the rear axle and
to prevent a step style torque input to the rear axle.
STEADY STATE, LOW TO MODERATE SPEED, NO
FRONT WHEEL SLIP, FORWARD DIRECTION
During normal driving conditions, (no wheel slip),
the inner shaft (front axle) and outer race (viscous
coupler) are running at different speeds due to the
different gear ratios between the front and rear dif-
ferentials. In this condition, the outer race is always
spinning faster (overdriving between 5-32 rpm) than
the inner shaft. When the BOC (Fig. 29) is running
under these conditions, at low vehicle speeds the
drag shoes and the cage keep the rollers up on the
left side (forward side) of the inner shaft flats. This is
what is known as ªoverrunning mode.º Notice that
when the clutch is in overrunning mode, the rollers
are spinning clockwise and with the outer race, thus
no torque is being transferred.
NOTE: Low speed, forward and reverse operation is
identical, just in opposite directions. (Fig. 29)
shows forward direction in reverse the rollers are
on the other side of the flats due to a reversal of
the cage force.
TRANSIENT CONDITION (BOC LOCKED), FRONT
WHEEL SLIP, FORWARD DIRECTION
When the front wheels lose traction and begin to
slip, the propeller shaft and rear axle pinion speed
difference decreases to zero. At this point the input
shaft (cam) becomes the driving member of the BOC
(Fig. 30), compressing the rollers against the outer
race. This locks the input shaft with the outer race
and transmits torque to the housing of the viscous
coupler, that in turn transmits torque to the rear
axle pinion. It should also be noted that when the
device is locked, the inner shaft and the outer race
are rotating at the same speed. The rollers are
pinched at this point and will stay locked until a
torque reversal (no front wheel slip) occurs. When
locked, the viscous coupler slips during the torque
transfer and the amount of torque transferred is
dependent on the coupling characteristic and the
amount of front wheel slip.
3 - 38 REAR DRIVELINE MODULERS
BI-DIRECTIONAL OVERRUNNING CLUTCH (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
4. Has undercoating been applied to
any unnecessary components?4. Clean undercoating as
necessary.
STEAM IS COMING FROM
FRONT OF VEHICLE
NEAR GRILL AREA WHEN
WEATHER IS WET,
ENGINE IS WARMED UP
AND RUNNING, AND
VEHICLE IS STATIONARY.
TEMPERATURE GAUGE
IS IN NORMAL RANGE1. During wet weather, moisture
(snow, ice, or rain condensation) on
the radiator will evaporate when the
thermostat opens. This opening
allows heated water into the radiator.
When the moisture contacts the hot
radiator, steam may be emitted. This
usually occurs in cold weather with
no fan or airflow to blow it away.1. Occasional steam emitting
from this area is normal. No
repair is necessary.
COOLANT ODOR 1. Coolant color is not necessarily an
indication of adequate corrosion or
temperature protection. Do not rely
on coolant color for determining
condition of coolant.1. Refer to Coolant in this group
for antifreeze tests. Adjust
antifreeze-to-water ratio as
necessary.
COOLANT LEVEL
CHANGES IN COOLANT
TANK. TEMPERATURE
GAUGE IS IN NORMAL
RANGE1. Level changes are to be expected
as coolant volume fluctuates with
engine temperature. If the level in
the tank was between the HOT and
COLD marks at normal engine
operating temperature, the level
should return to within that range
after operation at elevated
temperatures.1. This a normal condition. No
repair necessary.
DIAGNOSIS AND TESTING - COOLING SYSTEM
LEAK TEST
WARNING: THE WARNING WORDS ªDO NOT OPEN
HOTº ON THE RADIATOR PRESSURE CAP IS A
SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM
IS HOT OR UNDER PRESSURE.
With engine not running, remove pressure/vent cap
from the coolant recovery pressure container and
wipe the filler neck sealing seat clean. The coolant
recovery pressure container should be full.
Attach the Cooling System Tester 7700 or equiva-
lent to the radiator, as shown in (Fig. 1) and apply
104 kPa (15 psi) pressure. If the pressure drops more
than 13.8 kPa (2 psi) in 2 minutes, inspect all points
for external leaks.
All radiator and heater hoses should be shaken
while at 104 kPa (15 psi), since some leaks occur only
while driving due to engine movement.
If there are no external leaks, after the gauge dial
shows a drop in pressure, detach the tester. Startengine and run until the thermostat opens, allowing
the coolant to expand. Reattach the cooling system
tester. If the needle on the dial fluctuates it indicates
a combustion leak, usually a head gasket leak.
WARNING: WITH TOOL IN PLACE, PRESSURE WILL
BUILD UP FAST. EXCESSIVE PRESSURE BUILT UP,
BY CONTINUOUS ENGINE OPERATION, MUST BE
RELEASED TO A SAFE PRESSURE POINT. NEVER
PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).
If the needle on the dial does not fluctuate, raise
the engine rpm a few times. If an abnormal amount
of coolant or steam emits from the tailpipe, it may
indicate a coolant leak caused by a faulty head gas-
ket, cracked engine block, or cracked cylinder head.
There may be internal leaks that can be deter-
mined by removing the oil dipstick. If water globules
appear intermixed with the oil it will indicate an
internal leak in the engine. If there is an internal
leak, the engine must be disassembled for repair.
7a - 6 COOLING 2.5L TURBO DIESELRG
COOLING 2.5L TURBO DIESEL (Continued)

CD CHANGER
DESCRIPTION
The 4 Disc In-Dash CD Changer (if equipped) is
located in the instrument panel below the radio. The
remote changer does not use a cartridge or magazine
for the CD's. Up to 4 CD's can be directly loaded into
this unit.
OPERATION
Due to its compact design, the CD changer can
carry out only one operation at a time. For example,
you can not load a new disc while playing another at
the same time. Each operation happens sequentially.
The radio unit provides control over all features of
the CD changer with the exception of the CD load
and eject functions, which are controlled by buttons
located on the front of the CD changer. All features
you would expect, such as Disc Up/Down, Track
Up/Down, Random and Scan are controlled by the
radio, which also displays all relevant CD changer
information on the radio display.
The CD changer contains a Load/Eject button and
an indicator LED for each of the four disc positions
as well as an illuminated disc opening. The individ-
ual LED indicates whether a CD is currently loaded
in that particular chamber of the CD changer. Press-
ing the individual Load/Eject button for a particular
chamber will eject a disc currently present in that
chamber. If the chamber is currently empty, actuat-
ing the Load/Eject button will position that chamber
to receive and load a new disc in that chamber.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove screws holding CD changer.
(3) Disconnect the wire connector from the back of
the CD changer.
(4) Remove the CD changer from the vehicle (Fig.
5).
INSTALLATION
(1) Reconnect the wire connector to the CD
changer.
(2) Insert the CD changer into the instrument
panel.
NOTE: Use care when inserting CD changer so that
cable is not pinched or trapped against instrument
panel.
(3) Install screws holding CD changer.
(4) Reconnect the battery negative cable.
CHOKE
DIAGNOSIS AND TESTING
If the audio system is cutting in and out at higher
volumes, check for continuity across the choke con-
nector. If no continuity, replace the choke assembly.
The choke is located on the junction block/body con-
trol module.
D-PILLAR SPEAKER
REMOVAL
PASSENGER SIDE
(1) Disconnect and isolate the battery negative
cable.
(2) Remove rear header trim.
(3) Remove liftgate scuff plate.
(4) Remove upper seat belt bolt. (Refer to 8 -
ELECTRICAL/RESTRAINTS/SEAT BELT OUT-
BOARD FRONT - REMOVAL).
(5) Partially remove quarter trim panel to access
the D-pillar speaker.
(6) Slide the speaker from the retainer (Fig. 6).
(7) Disconnect the wire harness connector from the
speaker.
DRIVER SIDE
(1) Disconnect and isolate the negative battery
cable.
(2) Remove jack cover.
(3) Remove liftgate scuff plate.
(4) Partially remove quarter trim panel to access
the D-pillar speaker.
Fig. 5 CD - PLAYER
1 - CD-PLAYER
2 - POWER OUTLET
8A - 6 AUDIORS

²Engine running at 420 to 480 rpm for 10 sec-
onds
²Oil pressure switch closed to ground for (1 sec-
ond minimum, 2 seconds maximum)
Chime rate: 168 to 192 chimes per minute.
DIAGNOSIS AND TESTING - SEAT BELT CHIME
The seat belt chime will sound for 4 to 8 seconds,
when the ignition is turned on and the driver's seat
belt is not buckled (seat belt switch is closed to
ground). This is a reminder to the driver to buckle
the seat belt. The seat belt lamp is controlled by the
ORC. The cluster will also bulb check the seat belt
warning lamp for 6 seconds. Buckling the driver's
seat belt before the time out has expired will cause
the chime to stop immediately. Chime rate: 38 to 62
chimes per minute but the lamp will remain on until
6 seconds have expired.
To test the seat belt warning system, the ignition
switch must be in the OFF position for 1 minute
before starting the test. Turn the ignition switch to
the on position with the driver's seat belt not buck-
led. The seat belt warning lamp should light and the
chime should sound 4 to 8 seconds.
DIAGNOSIS AND TESTING - SEAT BELT LAMP
The seat belt lamp in the instrument cluster sig-
nals the vehicle passengers to fasten their seat belts.
The seat belt lamp is illuminated directly by the
instrument cluster for 6 seconds after the instrument
cluster receives the message from the ORC. The seat
belt lamp is therefore illuminated for 6 seconds
whenever the ignition switch is moved to run/start
position.
(1) While ignition is off, the seat belt lamp will not
be illuminated.
(2) The ignition power feed status will be updated
every 250 milliseconds or on change.
(3) This lamp will be checked by the instrument
cluster for 6 seconds with every run/start cycle of the
ignition switch.
DIAGNOSIS AND TESTING - TURN SIGNAL ON
CHIME
The turn signal on chime will warn the driver that
the turn signals have been left on. When the body
control module receives a turn signal input for 1/4.0
mile, vehicle speed is greater than 24 km/h (15 mph),
the chime will sound continuously until the turn sig-nal is turned OFF. If vehicle speed drops below 24
km/h (15 mph) prior to the warning being activated,
the accumulated distance traveled will be reset. The
turn signal chime is not activated when the emer-
gency flashers are turned on. Chime rate: 50612
chimes per minute.
For the turn signal warning system to operate:
²Must have input from either the right or left
turn signal lamps. Creates a voltage change between
0 and battery voltage.
²The vehicle speed sensor sends a message to the
Powertrain Control Module that vehicle has exceeded
24 km/h (15 mph) for 1/4.0 mile).
²When the above two conditions are met, the
chime will sound. The chime will stop when no fur-
ther voltage change is detected.
²If hazard warning signals are pulsing, no chime
will sound.
²If speed drops below 24 km/h (15 mph) before
the warning is issued, the warning will not be issued
and the distance counter will be reset.
²If turn signal lamps are not working properly,
the chime will not sound.
²When using the scan tool, refer to the proper
Body Diagnostic Manual for the procedure.
DIAGNOSIS AND TESTING - WARNING LAMP
ANNOUNCEMENT CHIME
The warning lamp announcement chime will warn
the driver to scan the instrument cluster to observe
which warning lamp is illuminated. Whenever the
volts, low fuel, airbag, door ajar or gate ajar lamps
are first illuminated, the chime will sound one tone.
The door/liftgate ajar warning lamp announcement
chime sounds only if the vehicle speed is above 4
m.p.h.
Two seconds after ignition switch is turned ON or
until the seat belt warning chime ends, all warning
announcement chimes will be consolidated into one
warning announcement. This will occur 2 seconds
after the seat belt warning chime ends. If a warning
announcement should occur while another warning
chime in progress (turn signal, low oil pressure or
high speed warnings), no additional chimes will
sound after the chime in progress ends. All associ-
ated lamps will be illuminated, and the active chime
will be the warning announcement.
RSCHIME/BUZZER8B-3
CHIME/BUZZER (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0071 Ambient Temp Sensor Preformance Ambient change less than 3É C in 200 Miles
P0106 (M) Barometric Pressure Out of Range MAP sensor input voltage out of an acceptable range
detected during reading of barometric pressure at key-on.
P0107 (M) Map Sensor Voltage Too Low MAP sensor input below minimum acceptable voltage.
P0108 (M) Map Sensor Voltage Too High MAP sensor input above maximum acceptable voltage.
P0111 (M) Intake Air Temp Sensor Preformance Intake Air change less than 3É C in 200 Miles
P0112 (M) Intake Air Temp Sensor Voltage Low Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
P0113 (M) Intake Air Temp Sensor Voltage High Intake air (charge) temperature sensor input above the
maximum acceptable voltage.
P0116 Engine Coolant Temp Performance A rationatilty error has been detected in the coolant temp
sensor.
P0117 (M) ECT Sensor Voltage Too Low Engine coolant temperature sensor input below the minimum
acceptable voltage.
P0118 (M) ECT Sensor Voltage Too High Engine coolant temperature sensor input above the
maximum acceptable voltage.
P0121 (M) TPS Voltage Does Not Agree With
MAPTPS signal does not correlate to MAP sensor signal.
P0122 (M) Throttle Position Sensor Voltage
LowThrottle position sensor input below the acceptable voltage
range.
P0123 (M) Throttle Position Sensor Voltage
HighThrottle position sensor input above the maximum
acceptable voltage.
P0125 (M) Engine Coolant Temp Not Reached Time to enter Closed Loop Operation (Fuel Control) is
excessive.
P0130 1/1 O2 Sensor Heater Relay Circuit An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P0131 (M) 1/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0132 (M) 1/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0133 (M) 1/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0134 (M) 1/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor input.
P0135 (M) 1/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0136 1/2 O2 Sensor Heater Relay Circuit An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P0137 (M) 1/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0138 (M) 1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0139 (M) 1/2 O2 Sensor Slow Response Oxygen sensor response not as expected.
8E - 10 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0350 Ignition Coil Draws Too Much
CurrentA coil (1-5) is drawing too much current.
P0351 (M) Ignition Coil # 1 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time.
P0352 (M) Ignition Coil # 2 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time.
P0353 (M) Ignition Coil # 3 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time.
P0354 (M) Ignition Coil # 4 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time (High Impedance).
P0355 (M) Ignition Coil # 5 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time (High Impedance).
P0356 (M) Ignition Coil # 6 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time (high impedance).
P0357 Ignition Coil # 7 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time (high impedance).
P0358 Ignition Coil # 8 Primary Circuit Peak primary circuit current not achieved with maximum
dwell time (high impedance).
P0401 (M) EGR System Failure Required change in air/fuel ration not detected during
diagnostic test.
P0403 (M) EGR Solenoid Circuit An open or shorted condition detected in the EGR solenoid
control circuit.
P0404 (M) EGR Position Sensor Rationality EGR position sensor signal does not correlate to EGR duty
cycle.
P0405 (M) EGR Position Sensor Volts Too Low EGR position sensor input below the acceptable voltage
range.
P0406 (M) EGR Position Sensor Volts Too High EGR position sensor input above the acceptable voltage
range.
P0412 Secondary Air Solenoid Circuit An open or shorted condition detected in the secondary air
(air switching/aspirator) solenoid control circuit.
P0420 (M) 1/1 Catalytic Converter Efficiency Catalyst 1/1 efficiency below required level.
P0432 (M) 1/2 Catalytic Converter Efficiency Catalyst 2/1 efficiency below required level.
P0441 (M) Evap Purge Flow Monitor Insufficient or excessive vapor flow detected during
evaporative emission system operation.
P0442 (M) Evap Leak Monitor 0.040 Leak
DetectedA 0.040 leak has been detected in the evaporative system.
P0443 (M) Evap Purge Solenoid Circuit An open or shorted condition detected in the EVAP purge
solenoid control circuit.
P0455 (M) Evap Leak Monitor Large Leak
DetectedA large leak has been detected in the evaporative system.
P0456 Evap Leak Monitor 0.020 Leak
DetectedA 0.020 leak has been detected in the evaporative system.
P0460 Fuel Level Unit No Change Over
MilesNo movement of fuel level sender detected.
RSELECTRONIC CONTROL MODULES8E-13
POWERTRAIN CONTROL MODULE (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0461 Fuel Level Unit No Changeover
TimeNo level of fuel level sender detected.
P0462 Fuel Level Sending Unit Volts Too
LowFuel level sensor input below acceptable voltage.
P0463 Fuel Level Sending Unit Volts Too
HighFuel level sensor input above acceptable voltage.
P0500 (M) No Vehicle Speed Sensor Signal No vehicle speed sensor signal detected during road load
conditions.
P0505 (M) Idle Air Control Motor Circuits Replace
P0508 Idle Air Control Motor Circuit Low Idle Air Control Motor Circuit input below acceptable current
P0509 Idle Air Control Motor Circuit High Idle Air Control Motor Circuit input above acceptable current
P0522 Oil Pressure Sens Low Oil pressure sensor input below acceptable voltage.
P0523 Oil Pressure Sens High Oil pressure sensor input above acceptable voltage.
P0551 (M) Power Steering Switch Failure Incorrect input state detected for the power steering switch
circuit. PL: High pressure seen at high speed.
P0600 (M) PCM Failure SPI Communications No communication detected between co-processors in the
control module.
P0601 (M) Internal Controller Failure Internal control module fault condition (check sum) detected.
P0604 Internal Trans Controller Transmission control module RAM self test fault detected.
-Aisin transmission.
P0605 Internal Trans Controller Transmission control module ROM self test fault detected
-Aisin transmission.
P0622 (G) Generator Field Not Switching
ProperlyAn open or shorted condition detected in the generator field
control circuit.
P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch relay
control circuit.
P0700 (M) EATX Controller DTC Present This SBEC III or JTEC DTC indicates that the EATX or Aisin
controller has an active fault and has illuminated the MIL via
a CCD (EATX) or SCI (Aisin) message. The specific fault
must be acquired from the EATX via CCD or from the Aisin
via ISO-9141.
P0703 (M) Brake Switch Stuck Pressed or
ReleasedIncorrect input state detected in the brake switch circuit.
(Changed from P1595).
P0711 Trans Temp Sensor, No Temp Rise
After StartRelationship between the transmission temperature and
overdrive operation and/or TCC operation indicates a failure
of the Transmission Temperature Sensor. OBD II Rationality.
P0712 Trans Temp Sensor Voltage Too Low Transmission fluid temperature sensor input below
acceptable voltage.
P0713 Trans Temp Sensor Voltage Too
HighTransmission fluid temperature sensor input above
acceptable voltage.
P0720 Low Output SPD Sensor RPM,
Above 15 MPHThe relationship between the Output Shaft Speed Sensor
and vehicle speed is not within acceptable limits.
8E - 14 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

OPERATION - SENSOR RETURN - PCM INPUT
The sensor return circuit provides a low electrical
noise ground reference for all of the systems sensors.
The sensor return circuit connects to internal ground
circuits within the Powertrain Control Module
(PCM).
OPERATION - SCI RECEIVE - PCM INPUT
SCI Receive is the serial data communication
receive circuit for the DRB scan tool. The Powertrain
Control Module (PCM) receives data from the DRB
through the SCI Receive circuit.
OPERATION - IGNITION SENSE - PCM INPUT
The ignition sense input informs the Powertrain
Control Module (PCM) that the ignition switch is in
the crank or run position.
OPERATION - PCM GROUND
Ground is provided through multiple pins of the
PCM connector. Depending on the vehicle there may
be as many as three different ground pins. There are
power grounds and sensor grounds.
The power grounds are used to control the ground
side of any relay, solenoid, ignition coil or injector.
The signal ground is used for any input that uses
sensor return for ground, and the ground side of any
internal processing component.
The SBEC III case is shielded to prevent RFI and
EMI. The PCM case is grounded and must be firmly
attached to a good, clean body ground.
Internally all grounds are connected together, how-
ever there is noise suppression on the sensor ground.
For EMI and RFI protection the case is also
grounded separately from the ground pins.
OPERATION - 8-VOLT SUPPLY - PCM OUTPUT
The PCM supplies 8 volts to the crankshaft posi-
tion sensor, camshaft position sensor.
OPERATION - 5 VOLT SUPPLY - PCM OUTPUT
The PCM supplies 5 volts to the following sensors:
²A/C pressure transducer
²Engine coolant temperature sensor
²Manifold absolute pressure sensor
²Throttle position sensor
²Linear EGR solenoid
OPERATION - MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygen
sensor diagnostics (they are checked for shorted con-
ditions at all times).
During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35É the PCM will wait 44
seconds.
²If the coolant is over 50ÉF the PCM will wait 38
seconds.
²If the coolant is over 167ÉF the PCM will wait
11 seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than 0.745
volts or less than 0.1 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
RSELECTRONIC CONTROL MODULES8E-19
POWERTRAIN CONTROL MODULE (Continued)