2001 CHRYSLER VOYAGER charging

valves at the service port connector ends. This will
prevent refrigerant from being released into the
atmosphere.
²LOW PRESSURE GAUGE HOSE- The low
pressure hose (Blue with Black stripe) attaches to
the suction (low side) service port. This port is
located on the suction line, near the compressor at
the front of the engine compartment.
²HIGH PRESSURE GAUGE HOSE- The high
pressure hose (Red with Black stripe) attaches to the
discharge (high side) service port. This port is located
on the liquid line near the filter-drier at the rear of
the engine compartment.
²RECOVERY/RECYCLING/EVACUATION/
CHARGING HOSE- The center manifold hose (Yel-
low, or White, with Black stripe) is used to recover,
evacuate, and charge the refrigerant system. When
the low or high pressure valves on the manifold
gauge set are opened, the refrigerant in the system
will escape through this hose.
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
After all refrigerant system leaks have been
repaired and the refrigerant system has been evacu-
ated, a refrigerant charge can be injected into the
system. For the proper amount of the refrigerant
charge, refer to REFRIGERANT CHARGE CAPAC-
ITY . A R-134a refrigerant recovery/recycling/charg-
ing station that meets SAE Standard J2210 must be
used to charge the refrigerant system with R-134a
refrigerant. See the operating instructions supplied
by the equipment manufacturer for proper care and
use of this equipment.
REFRIGERANT CHARGE CAPACITY
The R-134a refrigerant system charge capacity for
this vehicle is:
²Single or Dual Zone (Front Unit Only)- 0.96
kilograms (2.13 pounds or 34 ounces)
²Three Zone (Front and Rear Units)- 1.31
kilograms (2.88 pounds or 46 ounces)
CHARGING PROCEDURE
(1) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(2) A manifold gauge set and a R-134a refrigerant
recovery/recycling/charging station that meets SAE
Standard J2210 should still be connected to the
refrigerant system.
(3) Measure the proper amount of refrigerant and
heat it to 52É C (125É F) with the charging station.
See the operating instructions supplied by the equip-
ment manufacturer for proper use of this equipment.
(4) Open both the suction and discharge valves,
then open the charge valve to allow the heated
refrigerant to flow into the system.
(5) When the transfer of refrigerant has stopped,
close both the suction and discharge valves.
(6) If all of the refrigerant charge did not transfer
from the dispensing device, open all of the windows
in the vehicle and set the heater-air conditioner con-
trols so that the compressor is engaged and the
blower motor is operating at its lowest speed setting.
Run the engine at a steady high idle (about 1400
Fig. 33 Manifold Gauge Set - Typical
1 - HIGH PRESSURE GAUGE
2 - VALVE
3 - VACUUM/REFRIGERANT HOSE (YELLOW W/BLACK STRIPE)
4 - HIGH PRESSURE HOSE (RED W/BLACK STRIPE)
5 - LOW PRESSURE HOSE (BLUE W/BLACK STRIPE)
6 - VALVE
7 - LOW PRESSURE GAUGE
24 - 90 PLUMBING - FRONTRS
REFRIGERANT (Continued)

rpm). If the compressor will not engage, test the com-
pressor clutch control circuit and repair as required.
(7) Open the suction valve to allow the remaining
refrigerant to transfer to the refrigerant system.
WARNING:
TAKE CARE NOT TO OPEN THE DISCHARGE (HIGH
PRESSURE) VALVE AT THIS TIME.
(8) Close the suction valve and test the system
performance. (Refer to 24 - HEATING & AIR CON-
DITIONING - STANDARD PROCEDURE - A/C PER-
FORMANCE TEST).
(9) Disconnect the charging station and manifold
gauge set from the refrigerant system service ports.
(10) Reinstall the caps onto the refrigerant system
service ports.
STANDARD PROCEDURE - REFRIGERANT
SYSTEM EVACUATE
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
If the refrigerant system has been open to the
atmosphere, it must be evacuated before the system
can be charged. If moisture and air enters the system
and becomes mixed with the refrigerant, the com-
pressor head pressure will rise above acceptable
operating levels. This will reduce the performance of
the air conditioner and damage the compressor.
Evacuating the refrigerant system will remove the
air and boil the moisture out of the system at near
room temperature. A R-134a refrigerant recovery/re-
cycling/charging station that meets SAE Standard
J2210 must be used to evacuate the refrigerant sys-
tem. See the operating instructions supplied by the
equipment manufacturer for proper care and use of
this equipment. To evacuate the refrigerant system,
use the following procedure:
NOTE: When connecting the service equipment
couplings to the refrigerant system service ports,
be certain that the valve of each coupling is fully
closed. This will reduce the amount of effort
required to make the connection.
(1) Remove the caps from the refrigerant system
service ports and attach a manifold gauge set and a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 to the refriger-
ant system.(2) Open both the suction and discharge valves
and start the charging station vacuum pump.
(3) When the suction gauge has read 88 kPa (26
in. Hg.) vacuum or greater for 45 minutes, close both
the suction and discharge valves and turn off the
vacuum pump. If the refrigerant system fails to
reach the specified vacuum, the system has a leak
that must be corrected. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - FRONT/RE-
FRIGERANT - STANDARD PROCEDURE -
REFRIGERANT SYSTEM LEAKS).
(4) If the refrigerant system maintains the speci-
fied vacuum for thirty minutes, restart the vacuum
pump, open both the suction and discharge valves,
and evacuate the system for an additional ten min-
utes.
(5) Close both the suction and discharge valves,
and turn off the charging station vacuum pump.
(6) The refrigerant system is now ready to be
charged with R-134a refrigerant. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
STANDARD PROCEDURE - REFRIGERANT
RECOVERY
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to recover the refrigerant from an R-134a refrig-
erant system, whenever the refrigerant system must
be opened for service. See the operating instructions
supplied by the equipment manufacturer for the
proper care and use of this equipment.
REFRIGERANT OIL
DESCRIPTION
The refrigerant oil used in R-134a refrigerant sys-
tems is a synthetic-based, PolyAlkylene Glycol (PAG),
wax-free lubricant. Mineral-based R-12 refrigerant
oils are not compatible with PAG oils, and should
never be introduced to an R-134a refrigerant system.
There are different PAG oils available, and each con-
tains a different additive package. The 10S20H com-
pressor used in this vehicle are designed to use an
RSPLUMBING - FRONT24-91
REFRIGERANT (Continued)

through the rear evaporator when the rear air condi-
tioner is turned Off.
DIAGNOSIS AND TESTING - EXPANSION VALVE
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
NOTE: The expansion valve should only be tested
following testing of the compressor.
NOTE: Liquid CO
2is required to test the expansion
valve. This material is available from most welding
supply facilities. Liquid CO
2is also available from
companies which service and sell fire extinguish-
ers.
When testing the expansion valve, the work area
and the vehicle temperature must be 21É to 27É C
(70É to 85É F). To test the expansion valve:
(1) Connect a charging station or manifold gauge
set to the refrigerant system service ports. Verify the
refrigerant charge level.
(2) Close all doors, windows and vents to the pas-
senger compartment.
(3) Set the heater-air conditioner controls so that
the compressor is operating, the temperature control
is in the highest temperature position, the mode door
is directing the output to the floor outlets, and the
blower is operating at the highest speed setting.
(4) Start the engine and allow it to idle at 1000
rpm. After the engine has reached normal operating
temperature, allow the passenger compartment to
heat up. This will create the need for maximum
refrigerant flow into the evaporator.
(5) If the refrigerant charge is sufficient, the dis-
charge (high pressure) gauge should read 965 to 1655
kPa (140 to 240 psi). The suction (low pressure)
gauge should read 140 kPa to 207 kPa (20 psi to 30
psi). If OK, go to Step 6. If not OK, replace the faulty
expansion valve.
WARNING:
PROTECT THE SKIN AND EYES FROM EXPOSURE
TO LIQUID CO
2. PERSONAL INJURY CAN RESULT.
(6) If the suction (low pressure) gauge reads
within the specified range, freeze the expansion valve
control head for 30 seconds using liquid CO
2or
another suitable super-cold material.Do not spray
R-134a or R-12 refrigerant on the expansionvalve control head for this test.The suction (low
pressure) gauge reading should drop by 10 psi. If OK,
go to Step 7 If not OK, replace the faulty expansion
valve.
(7) Allow the expansion valve control head to thaw.
The suction (low pressure) gauge reading should sta-
bilize at 140 kPa to 240 kPa (20 psi to 30 psi). If not
OK, replace the faulty expansion valve.
(8) When expansion valve testing is complete, test
the overall air conditioner performance. (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - A/C PERFORMANCE TEST).
Remove all test equipment before returning the vehi-
cle to service.
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING),
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING),
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - HEATER PLUMB-
ING).
(1) Remove the rear heater-A/C unit housing from
the vehicle. (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/REAR HEATER-
A/C HOUSING - REMOVAL).
(2) Carefully remove the foam insulator wrap from
the rear expansion valve.
(3) Remove the rear evaporator line extension from
the expansion valve. (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - REAR/EVAPORA-
TOR - REMOVAL - EVAPORATOR LINE EXTEN-
SION).
(4) If the vehicle is equipped with the optional
Automatic Temperature Control (ATC) system, dis-
connect the expansion valve solenoid pigtail wire con-
nector from the rear HVAC wire harness connector
(Fig. 4).
(5) Remove the two screws that secure the expan-
sion valve to the evaporator tube sealing plate.
(6) Remove the expansion valve from the evapora-
tor tubes.
(7) Remove the seals from the evaporator tube fit-
tings and discard.
(8) Install plugs in, or tape over the opened evap-
orator tube fittings and both expansion valve ports.
INSTALLATION
(1) Remove the tape or plugs from the evaporator
tube fittings and both expansion valve ports.
RSPLUMBING - REAR24-99
EXPANSION VALVE (Continued)

REFRIGERANT
DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM CHARGE LEVEL 2.5L DIESEL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
NOTE: The proper amount of R-134a refrigerant for
the refrigerant system in this model is:
²Single or Dual Zone (Front Unit Only - 2.5L Die-
sel) ± 0.91 kilograms (2.00 pounds or 32 ounces)
²Single or Dual Zone (Front Unit Only) - 0.96
kilograms (2.13 pounds or 34 ounces)
²Three Zone (Front and Rear Units) - 1.31 kilo-
grams (2.88 pounds or 46 ounces)
The procedure that follows should be used to deter-
mine whether the refrigerant system contains the
proper refrigerant charge. Symptoms of an improper
refrigerant charge (low) include: poor air conditionerperformance, fog emitted from the air conditioner out-
lets, a hissing sound from the expansion valve/evapo-
rator area. There are two different methods with
which the refrigerant charge level may be tested:
²Using a DRBIIItscan tool, a thermocouple and
the Charge Determination Chart (Fig. 3). Refer to
the appropriate diagnostic information.
²Using a manifold gauge set, a thermocouple and
the Charge Determination Chart (Fig. 3).
A temperature probe is required to measure liquid
line temperature. The clamp-on, Type K thermocou-
ple temperature probe used in this procedure is
available through the DaimlerChrysler Professional
Service Equipment (PSE) program. This probe (PSE
#66-324-0014 or #80PK-1A) is compatible with tem-
perature-measuring instruments that accept Type K
thermocouples, and have a miniature connector
input. Other temperature probes are available
through aftermarket sources; however, all references
in this procedure will reflect the use of the probe
made available through the PSE program.
In order to use the temperature probe, a digital ther-
mometer will also be required. If a digital thermometer
is not available, an adapter is available through the
PSE program that will convert any standard digital
multimeter into a digital thermometer. This adapter is
designed to accept any standard Type K thermocouple.
If a digital multimeter is not available, this tool is also
available through the PSE program.
NOTE: When connecting the service equipment
couplings to the refrigerant system service ports,
be certain that the valve of each coupling is fully
closed. This will reduce the amount of effort
required to make the connection.
(1) Remove the caps from the refrigerant system
service ports and attach a manifold gauge set or a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 to the refriger-
ant system.
(2) Attach a clamp-on thermocouple to the liquid
line. The thermocouple must be placed as close to the
A/C pressure transducer as possible to accurately
observe liquid line temperature.
(3) Bring the refrigerant system up to operating
temperature and pressure. This is done by allowing
the engine to run at idle under the following condi-
tions for five minutes.
(a) Front windows are open.
(b) Transaxle in Park.
(c) Front heater-A/C controls set to outside air,
full cool, panel mode, blower high, and compressor
engaged.
(d)
If the vehicle is so equipped, the rear heater-
A/C controls must be set to full cool and blower high.
Fig. 2 AIR INTAKE AND HEATER PIPE ASSEMBLY
1 - INTAKE TUBE AIR INTAKE
2 - INTAKE PIPE
3 - RETAINING SCREWS
4 - INTAKE HEATER LINE
5 - RETURN HEATER LINE
24a - 4 HEATING & AIR CONDITIONINGRG
HEATER PIPES - DIESEL SUPPLEMENTAL HEATER (Continued)

TABLE OF CONTENTS
1.0 INTRODUCTION.........................................................1
1.1SYSTEM COVERAGE...............................................1
1.2SIX-STEP TROUBLESHOOTING PROCEDURE..........................1
2.0 IDENTIFICATION OF SYSTEM.............................................1
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION......................1
3.1GENERAL DESCRIPTION............................................1
3.2FUNCTIONAL OPERATION...........................................1
3.2.1FUEL CONTROL.............................................1
3.2.2ON-BOARD DIAGNOSTICS....................................2
3.2.3OTHER CONTROLS..........................................4
3.2.4PCM OPERATING MODES....................................4
3.2.5NON-MONITORED CIRCUITS..................................5
3.2.6SKIS OVERVIEW............................................5
3.2.7SKIM ON-BOARD DIAGNOSTICS...............................6
3.2.8SKIS OPERATION............................................6
3.2.9PROGRAMMING THE POWERTRAIN CONTROL MODULE..........6
3.2.10PROGRAMMING THE SENTRY KEY IMMOBILIZER MODULE.......7
3.2.11PROGRAMMING THE IGNITION KEYS TO THE SENTRY KEY
IMMOBILIZER MODULE.......................................7
3.3DIAGNOSTIC TROUBLE CODES......................................7
3.3.1HARD CODE................................................7
3.3.2INTERMITTENT CODE........................................8
3.3.3DISTANCE SINCE MI SET.....................................8
3.3.4HANDLING NO DTC PROBLEMS...............................8
3.4USING THE DRBIIIT................................................10
3.5DRBIIITERROR MESSAGES AND BLANK SCREEN.....................10
3.5.1DRBIIITDOES NOT POWER UP...............................10
3.5.2DISPLAY IS NOT VISIBLE....................................10
4.0 DISCLAIMERS, SAFETY, WARNINGS......................................10
4.1DISCLAIMERS.....................................................10
4.2SAFETY..........................................................10
4.2.1TECHNICIAN SAFETY INFORMATION..........................10
4.2.2VEHICLE PREPARATION FOR TESTING........................11
4.2.3SERVICING SUB ASSEMBLIES................................11
4.2.4DRBIIITSAFETY INFORMATION..............................11
4.3WARNINGS AND CAUTIONS.........................................11
4.3.1ROAD TEST WARNINGS.....................................11
4.3.2VEHICLE DAMAGE CAUTIONS................................11
5.0 REQUIRED TOOLS AND EQUIPMENT.....................................12
6.0 GLOSSARY OF TERMS..................................................12
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES...........................15
CHARGING
P0622-GENERATOR FIELD NOT SWITCHING PROPERLY.....................16
P1594-CHARGING SYSTEM VOLTAGE TOO HIGH...........................18
i

TABLE OF CONTENTS - Continued
P1682-CHARGING SYSTEM VOLTAGE TOO LOW............................20
COMMUNICATION
P0600-PCM FAILURE SPI COMMUNICATIONS...............................23
P0601-PCM INTERNAL CONTROLLER FAILURE.............................23
P1685-WRONG OR INVALID KEY MSG RECEIVED FROM SKIM................24
P1686-NO SKIM BUS MESSAGE RECEIVED................................26
P1695-NO CCD/J1850 MESSAGE FROM BODY CONTROL MODULE............28
P1696-PCM FAILURE EEPROM WRITE DENIED.............................30
P1697-PCM FAILURE SRI MILE NOT STORED...............................30
P1698-NO BUS MESSAGE FROM TRANS CONTROL MODULE................32
*BUS +/- SIGNALS OPEN FROM SENTRY KEY IMMOBILIZER MODULE.........34
*NO RESPONSE FROM PCM (PCI BUS)....................................36
*NO RESPONSE FROM PCM (SCI ONLY)...................................37
*PCI BUS COMMUNICATION FAILURE.....................................40
DRIVEABILITY - GAS
P0071 - AMBIENT TEMP SENSOR PERFORMANCE..........................43
P0106-BAROMETRIC PRESSURE OUT OF RANGE..........................45
P0107-MAP SENSOR VOLTAGE TOO LOW.................................48
P0108-MAP SENSOR VOLTAGE TOO HIGH.................................51
P0117-ECT SENSOR VOLTAGE TOO LOW..................................54
P0118-ECT SENSOR VOLTAGE TOO HIGH.................................56
P0121-TPS VOLTAGE DOES NOT AGREE WITH MAP........................59
P0122-THROTTLE POSITION SENSOR VOLTAGE LOW.......................64
P0123-THROTTLE POSITION SENSOR VOLTAGE HIGH......................68
P0125-CLOSED LOOP TEMP NOT REACHED...............................71
P0131-1/1 O2 SENSOR SHORTED TO GROUND.............................73
P0137-1/2 O2 SENSOR SHORTED TO GROUND.............................73
P0132-1/1 O2 SENSOR SHORTED TO VOLTAGE............................76
P0138-1/2 O2 SENSOR SHORTED TO VOLTAGE............................76
P0133-1/1 O2 SENSOR SLOW RESPONSE.................................79
P0139-1/2 O2 SENSOR SLOW RESPONSE.................................79
P0134-1/1 O2 SENSOR STAYS AT CENTER.................................82
P0140-1/2 O2 SENSOR STAYS AT CENTER.................................82
P0135-1/1 O2 SENSOR HEATER FAILURE..................................85
P0141-1/2 O2 SENSOR HEATER FAILURE..................................88
P0171-1/1 FUEL SYSTEM LEAN...........................................90
P0172-1/1 FUEL SYSTEM RICH...........................................95
P0201-INJECTOR #1 CONTROL CIRCUIT..................................100
P0202-INJECTOR #2 CONTROL CIRCUIT..................................100
P0203-INJECTOR #3 CONTROL CIRCUIT..................................100
P0204-INJECTOR #4 CONTROL CIRCUIT..................................100
P0205-INJECTOR #5 CONTROL CIRCUIT..................................100
P0206-INJECTOR #6 CONTROL CIRCUIT..................................100
P0300-MULTIPLE CYLINDER MIS-FIRE....................................103
P0301-CYLINDER #1 MISFIRE...........................................103
P0302-CYLINDER #2 MISFIRE...........................................103
P0303-CYLINDER #3 MISFIRE...........................................103
P0304-CYLINDER #4 MISFIRE...........................................103
P0305-CYLINDER #5 MISFIRE...........................................103
P0306-CYLINDER #6 MISFIRE...........................................103
P0320-NO CRANK REFERENCE SIGNAL AT PCM...........................108
ii

1.0 INTRODUCTION
The procedures contained in this manual include
specifications, instructions, and graphics needed to
diagnose the PCM Powertrain System. The diag-
nostics in this manual are based on the failure
condition or symptom being present at time of
diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the appropriate modules; ie., if the DRBIIIt
displays a No Response condition, you must
diagnose this first before proceeding.
2. Read DTC's (diagnostic trouble codes) with the
DRBIIIt.
3. If no DTC's are present, identify the customer
complaint.
4. Once the DTC or customer complaint is identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All system
schematics are in Section 10.0.
An * placed before the symptom description indi-
cates a customer complaint.
When repairs are required, refer to the appropri-
ate service information for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added; carryover sys-
tems may be enhanced. READ THIS DIAGNOSTIC
INFORMATION BEFORE TRYING TO DIAG-
NOSE A VEHICLE CODE. It is recommended that
you review the entire diagnostic information to
become familiar with all new and changed diagnos-
tic procedures.
If you have any comments or recommendations
after reviewing the diagnostic information, please
fill out the form at the back of the book and mail it
back to us.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers the
following 2001 Town and Country; Caravan/Grand
Caravan; and Voyager/Grand Voyager vehicles
equipped with the 2.4L and the 3.3L/3.8L engines.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the powertrain control module
(PCM) is done in six basic steps:
²verification of complaint
²verification of any related symptoms
²symptom analysis
²problem isolation
²repair of isolated problem
²verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
The Powertrain Control Module (PCM) monitors
and controls:
²Fuel System
²Idle Air Control System
²Ignition System
²Charging System
²Speed Control System
²Cooling system
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 GENERAL DESCRIPTION
These Sequential Fuel Injection (SFI) engine sys-
tems have the latest in technical advances. The
on-board Euro Stage III OBD diagnostics incorpo-
rated with the Powertrain Control Module (PCM)
are intended to assist the field technician in repair-
ing vehicle problems by the quickest means.
3.2 FUNCTIONAL OPERATION
3.2.1 FUEL CONTROL
The PCM controls the air/fuel ratio of the engine
by varying fuel injector on time. Mass air flow is
calculated using the speed density method using
enigne speed, manifold absolute pressure, and air
temperature change.
Different fuel calculation strategies are used de-
pending on the operational state of the engine.
During crank mode, a prime shot fuel pulse is
delivered followed by fuel pulses determined by a
crank time strategy. Cold engine operation is deter-
mined via an open loop strategy until the O2
sensors have reached operating temperature. At
this point, the strategy enters a closed loop mode
where fuel requirements are based upon the state of
the O2 sensors, engine speed, MAP, throttle posi-
tion, air temperature, battery voltage, and coolant
temperature.
1
GENERAL INFORMATION

3.2.3 OTHER CONTROLS
CHARGING SYSTEM
The charging system is turned on when the
engine is started and ASD relay energized. When
the ASD relay is on, ASD output voltage is supplied
to the ASD sense circuit at the PCM. This voltage is
connected in some cases, through the PCM and
supplied to one of the generator field terminals
(Gen Source +). All others, the Gen field is con-
nected directly to the ASD output voltage. The
amount of current produced by the generator is
controlled by the Electronic Voltage Regulator
(EVR) circuitry, in the PCM. Battery temperature is
determined from IAT. This temperature along with
sensed line voltage, is used by the PCM to vary the
battery charging rate. This is done by cycling the
ground path to the other generator field terminal
(Gen field driver).
SPEED CONTROL SYSTEM
The PCM controls vehicle speed by operation of
the speed control servo vacuum and vent solenoids.
Energizing the vacuum solenoid applies vacuum to
the servo to increase throttle position. Operation of
the vent solenoid slowly releases the vacuum allow-
ing throttle position to decrease. A special dump
solenoid allows immediate release of throttle posi-
tion caused by braking, cruise control switch turned
off, shifting into neutral, excessive RPM (tires spin-
ning) or ignition off.
LEAK DETECTION PUMP SYSTEM (IF EQUIPPED)
The leak detection pump is a device that pressur-
izes the evaporative system to determine if there
are any leaks. When certain conditions are met, the
PCM will activate the pump and start counting
pump strokes. If the pump stops within a calibrated
number of strokes, the system is determined to be
normal. If the pump does not stop or stops too soon,
a DTC will be set.
3.2.4 PCM OPERATING MODES
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. There are several different
modes of operation that determine how the PCM
responds to the various input signals.
There are two types of engine control operation:
open loopandclosed loop.
Inopen loopoperation, the PCM receives input
signals and responds according to preset program-
ming. Inputs from the heated oxygen sensors are
not monitored.Inclosed loopoperation, the PCM monitors the
inputs from the heated oxygen sensors. This input
indicates to the PCM whether or not the calculated
injector pulse width results in the ideal air-fuel
ratio of 14.7 parts air to 1 part fuel. By monitoring
the exhaust oxygen content through the oxygen
sensor, the PCM can fine tune injector pulse width.
Fine tuning injector pulse width allows the PCM to
achieve the lowest emission levels while maintain-
ing optimum fuel economy.
The engine start-up (crank), engine warm-up,
and wide open throttle modes are open loop modes.
Under most operating conditions, closed loop modes
occur with the engine at operating temperature.
IGNITION SWITCH ON (ENGINE OFF) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
1. The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic
fuel strategy.
2. The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input.
The PCM modifies fuel strategy based on this
input.
When the key is in the on position and the engine
is not running (zero rpm), the auto shutdown relay
and fuel pump relay are not energized. Therefore,
voltage is not supplied to the fuel pump, ignition
coil, and fuel injectors.
Engine Start-up ModeÐ This is an open loop
mode. The following actions occur when the starter
motor is engaged:
1. The auto shutdown and fuel pump relays are
energized. If the PCM does not receive the cam-
shaft and crankshaft signal within approxi-
mately one second, these relays are de-
energized.
2. The PCM energizes all fuel injectors until it
determines crankshaft position from the cam-
shaft and crankshaft signals. The PCM deter-
mines crankshaft position within one engine
revolution. After the camshaft position has been
determined, the PCM energizes the fuel injectors
in sequence. The PCM adjusts the injector pulse
width and synchronizes the fuel injectors by
controlling the fuel injectors' ground paths.
3. Once the engine idles within 64 rpm of its target
engine speed, the PCM compares the current
MAP sensor value with the value received dur-
ing the ignition switch on (zero rpm) mode. A
diagnostic trouble code is written to PCM mem-
ory if a minimum difference between the two
values is not found.
4
GENERAL INFORMATION