2001 DODGE TOWN AND COUNTRY light

COOLING 2.5L TURBO DIESEL
TABLE OF CONTENTS
page page
COOLING 2.5L TURBO DIESEL
DESCRIPTION............................1
DIAGNOSIS AND TESTING..................1
COOLING SYSTEM......................1
COOLING SYSTEM LEAK TEST.............6
COOLING SYSTEM FLOW CHECK..........7COOLING SYSTEM AERATION.............7
CLEANING...............................7
INSPECTION.............................7
SPECIFICATIONS.........................8
ACCESSORY DRIVE.......................9
ENGINE................................14
COOLING 2.5L TURBO DIESEL
DESCRIPTION - COOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible, maintains
normal operating temperature and prevents over-
heating.
The cooling system also provides a means of heat-
ing the passenger compartment. The cooling system
is pressurized and uses a centrifugal water pump to
circulate coolant throughout the system. A separate
and remotely mounted, pressurized coolant tank
using a pressure/vent cap is used.
COOLING SYSTEM COMPONENTS
The cooling system consists of:
²Charge Air Cooler
²Electric Cooling Fans
²A aluminum-core radiator with plastic side
tanks
²A separate pressurized coolant tank
²A pressure/vent cap on the coolant tank
²Fan shroud
²Thermostat
²Coolant
²Low coolant warning lamp
²Coolant temperature gauge
²Water pump
²Hoses and hose clamps
DIAGNOSIS AND TESTING - COOLING SYSTEM
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
(1) PROLONGED IDLE, VERY HIGH AMBIENT
TEMPERATURE, SLIGHT TAIL WIND AT IDLE,
SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED
OR STEEP GRADES.
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.
²Increasing engine speed for more air flow is rec-
ommended.
(2) TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
(3) RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt
²Brakes (possibly dragging)
²Changed parts (incorrect water pump)
²Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, refer to following Cooling System Diagnosis
charts.
These charts are to be used as a quick-reference
only.
RGCOOLING 2.5L TURBO DIESEL7a-1
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CONDITION POSSIBLE CAUSES CORRECTION
6. Freeze point of antifreeze not
correct. Mixture may be too rich.6. Check antifreeze. Adjust
antifreeze-to-water ratio as
required.
7. Coolant not flowing through
system.7. Check for coolant flow in
coolant tank with engine warm
and thermostat open. Coolant
should be observed flowing
through the tank. If flow is not
observed, determine reason for
lack of flow and repair as
necessary.
8. Radiator or A/C condensor fins
are dirty or clogged.8. Clean debris from radiator or
A/C condensor
9. Radiator core is corroded or
plugged.9. Have radiator re-cored or
replaced.
10. Aftermarket A/C installed without
proper A/C condensor.10. Install proper A/C
condensor.
11. Dragging Brakes. 11. Check and correct as
necessary.
12. Non-factory bug screen is being
used reducing airflow.12. Only a factory screen
should be used.
13. Thermostat partially or
completely shut. This is more
prevalent on high mileage vehicles.13. Check thermostat and
replace if necessary.
14. Cylinder head gasket leaking. 14. Check cylinder head gasket
for leaks.
15. Heater core leaking. 15. Check heater cor for leaks.
Repair as necessary.
TEMPERATURE GAUGE
READING IS
INCONSISTENT
(FLUCTUATES, CYCLES
OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly. Fluctuation is also
influenced by loads, outside
temperature and extended idle time
with diesel engines.1. A normal condition. No
correction is necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge
and repair as necessary.
3. Gauge reading rises when vehicle
is brought to a stop after heavy use
(engine still running).3. A normal condition. No
correction needed. Gauge
should return to normal range
after vehicle is driven.
4. Gauge reading high after starting
a warm-iup (hot) engine.4. A normal condition. No
correction needed. Gauge
should return to normal after a
few minutes of engine
operation.
RGCOOLING 2.5L TURBO DIESEL7a-3
COOLING 2.5L TURBO DIESEL (Continued)
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100 Percent Ethylene-GlycolÐShould Not Be Used in
Chrysler Vehicles
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149 deg. C (300 deg. F). This temperature is hot
enough to melt plastic and soften solder. The
increased temperature can result in engine detona-
tion. In addition, 100 percent ethylene-glycol freezes
at -22 deg. C (-8 deg. F ).
Propylene-glycol FormulationsÐShould Not Be Used in
Chrysler Vehicles
Propylene-glycol formulations do not meet
Chrysler coolant specifications.It's overall effec-
tive temperature range is smaller than that of ethyl-
ene-glycol. The freeze point of 50/50 propylene-glycol
and water is -32 deg. C (-26 deg. F). 5 deg. C higher
than ethylene-glycol's freeze point. The boiling point
(protection against summer boil-over) of propylene-
glycol is 125 deg. C (257 deg.F)at96.5 kPa (14 psi),
compared to 128 deg. C (263 deg. F) for ethylene-gly-
col. Use of propylene-glycol can result in boil-over or
freeze-up in Chrysler vehicles, which are designed for
ethylene-glycol. Propylene glycol also has poorer heat
transfer characteristics than ethylene glycol. This
can increase cylinder head temperatures under cer-
tain conditions.
Propylene-glycol/Ethylene-glycol MixturesÐShould Not Be
Used in Chrysler Vehicles
Propylene-glycol/ethylene-glycol Mixtures can
cause the destabilization of various corrosion inhibi-
tors, causing damage to the various cooling system
components. Also, once ethylene-glycol and propy-
lene-glycol based coolants are mixed in the vehicle,
conventional methods of determining freeze point will
not be accurate. Both the refractive index and spe-
cific gravity differ between ethylene glycol and propy-
lene glycol.
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.DIAGNOSIS AND TESTING - COOLANT
CONCENTRATION TESTING
Coolant concentration should be checked when any
additional coolant was added to system or after a
coolant drain, flush and refill. The coolant mixture
offers optimum engine cooling and protection against
corrosion when mixed to a freeze point of -37ÉC
(-34ÉF) to -59ÉC (-50ÉF). The use of a hydrometer or a
refractometer can be used to test coolant concentra-
tion.
A hydrometer will test the amount of glycol in a
mixture by measuring the specific gravity of the mix-
ture. The higher the concentration of ethylene glycol,
the larger the number of balls that will float, and
higher the freeze protection (up to a maximum of
60% by volume glycol).
A refractometer will test the amount of glycol in a
coolant mixture by measuring the amount a beam of
light bends as it passes through the fluid.
Some coolant manufactures use other types of gly-
cols into their coolant formulations. Propylene glycol
is the most common new coolant. However, propylene
glycol based coolants do not provide the same freez-
ing protection and corrosion protection and is not rec-
ommended.
CAUTION: Do not mix types of coolantÐcorrosion
protection will be severely reduced.
STANDARD PROCEDURE - COOLANT SERVICE
For engine coolant recommended service schedule,
(Refer to LUBRICATION & MAINTENANCE/MAIN-
TENANCE SCHEDULES - DESCRIPTION).
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT
The pressure/vent cap should not be removed
from the coolant recovery pressure container.
When additional coolant is needed to maintain this
level, it should be added to the coolant recovery pres-
sure container (Fig. 1). Use only 50/50 mix of ethyl-
ene glycol type antifreeze and distilled water. For the
recommeded antifreeze/coolant type (Refer to LUBRI-
CATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended. For the
recommeded antifreeze/coolant type (Refer to
LUBRICATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
RGENGINE7a-15
COOLANT (Continued)
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INSPECTION
Hold the cap in your hand,top side up(Fig. 21).
The vent valve at the bottom of the cap should open.
If the rubber gasket has swollen, preventing the
valve from opening, replace the cap.
Hold the cleaned cap in your hand,upside down.
If any light can be seen between vent valve and the
rubber gasket, replace the cap.Do not use a
replacement cap that has a spring to hold the
vent shut.
A replacement cap must be of the type designed for
coolant reserve systems. This design ensures coolant
return to the radiator.
RADIATOR FAN
DESCRIPTION
The dual radiator fans are mounted to the back
side of the radiator (Fig. 22). The radiator fan consist
of the fan blade, electric motor and a support shroud
which are all serviced as an assembly.
OPERATION
RADIATOR FAN OPERATION CHART
COOLANT TEMPERATURE A/C PRESSURE
Fan Operation
Speeds:Initial Max Initial Max
Fan On: 104ÉC (220ÉF) 110ÉC (230ÉF) Fan
Speed Duty-Cycles
(Ramps-up) from
30% to 99%1,724 Kpa (250 psi) 2,068 Kpa (300 psi)
Fan Speed
Duty-Cycles
(Ramps-up) from
30% to 99%
Fan Off: 101ÉC (214ÉF) Fan Speed
Duty-Cycles
(Ramps-down) from
99% to 30%1,710 Kpa (248 psi) Fan Speed
Duty-Cycles
(Ramps-down) from
99% to 30%
DIAGNOSIS AND TESTING - RADIATOR FAN MOTOR
RADIATOR FAN DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
NOISY RADIATOR FAN 1. Fan blade loose. 1. Replace fan assembly. (Refer to
7 - COOLING/ENGINE/RADIATOR
FAN - REMOVAL)
2. Fan blade striking a surrounding
object.2. Locate point of fan blade contact
and repair as necessary.
3. Air obstructions at radiator or A/C
condenser.3. Remove obstructions and/or
clean debris.
4. Electric fan motor defective. 4. Replace fan assembly. (Refer to
7 - COOLING/ENGINE/RADIATOR
FAN - REMOVAL)
ELECTRIC FAN MOTOR DOES
NOT OPERATE1. Fan relay, powertrain control
module (PCM), coolant temperature
sensor, or wiring defective.1. (Refer to Appropriate Diagnostic
Information) Repair as necessary.
2. Defective A/C pressure
transducer.2. (Refer to Appropriate Diagnostic
Information) Repair as necessary.
7a - 26 ENGINERG
RADIATOR PRESSURE CAP (Continued)
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FASTEN SEAT BELT LAMP OR TONE CONTINUES
FOR MORE THAN 10 SECONDS AFTER SEAT
BELTS ARE FASTENED AND DRIVER'S DOOR IS
CLOSED.
Refer to the proper Body Diagnostic Procedures
manual.
NO TONE WHEN PARK OR HEADLAMPS ARE ON
AND DRIVER'S DOOR IS OPEN.
Make sure ignition is in lock position with the key
removed.
(1) Check the BCM DTC's and BCM sensors to
verify the door is open. Repair as necessary.
(2) Actuate Chime (BCM actuates).
(3) Inspect BCM connectors and wires for proper
connection.
(4) Measure with a voltmeter the voltage (12v) on
BCM connector (PX2) pin 34 with harness connected.
DIAGNOSIS AND TESTING - DOME LAMP ON
CHIME
The dome lamp on chime will warn the driver that
the dome lamps have been left on.
When the ignition is OFF:
²Driver's door OPEN (door ajar switch is closed to
ground) and
²Dome lamps are ON (dome lamp switch is closed
to ground),
The chime will sound continuously until driver's
door is closed, dome lamps tuned OFF or until the
battery protection time out of 15 minutes has
expired. Chime rate: 168 to 192 chimes per minute.
DIAGNOSIS AND TESTING - ENGINE
TEMPERATURE CRITICAL CHIME
The engine temperature critical chime will warn
the driver that the vehicle's engine is overheating.
While monitoring the coolant temperature, the Pow-
ertrain Control Module (PCM) will send on the PCI
data bus as engine temperature every 1.376 seconds
to the cluster. The MIC calculates engine tempera-
ture and determines if a warning should occur. This
feature is functional only with the Ignition Switch in
the Run/Start position.
When the engine temperature reaches 122ÉC
(252ÉF) the MIC requests a chime from the BCM and
the engine temperature lamp comes ON. The MIC
turns OFF the lamp when the engine temperature
reaches 117ÉC (242ÉF). The MIC will chime continu-
ously (request from the BCM). The chime will turn
OFF after four minutes or when the temperature
reaches 117ÉC (242ÉF), which ever occurs first.
DIAGNOSIS AND TESTING - EXTERIOR LAMPS
ON CHIME
The exterior lamp on chime will warn the driver
that the exterior lights have been left on.
With the ignition switch OFF/key out of ignition:
²Driver's door is open (door ajar switch is closed
to ground)
²Parking lamps or headlamps ON (parking lamp
switch is closed to ground)
The chime will sound until lights are turned OFF,
driver's door closed or until the battery protection
time out of 3 minutes has expired.
Chime rate: 168 to 192 chimes per minute.
To test the exterior lamps left on function:
²Turn ignition off
²Remove ignition key
²Turn exterior lamps on with driver's door open.
Chime should sound until lamps are turned off or
driver's door is closed.
DIAGNOSIS AND TESTING - KEY-IN IGNITION
CHIME
The key-in ignition chime will act as a warning to
the driver that the ignition key has been left in the
ignition switch.
With the ignition switch is in OFF position ONLY:
²Driver's door is open/ajar (door ajar switch is
closed to ground)
²Key is in the ignition switch (ignition is in the
LOCK position)
The chime will sound until one of the above condi-
tions is removed or until battery protection time out
(15 min.) has expired. Chime rate: 168 to 192 chimes
per minute.
To test the key-in ignition function, insert key into
the ignition and open driver's door. Do not turn igni-
tion ON. Chime should sound until key is removed
from ignition or driver's door is closed.
For diagnosis and testing of the Key-In Accessory
chime, use the same testing procedure as above but
with the key in the accessory position.
DIAGNOSIS AND TESTING - LOW OIL
PRESSURE CHIME
The low oil pressure chime will warn the driver
that the engine oil pressure is low. The oil pressure
switch will close to ground during a low oil pressure
condition. The oil pressure lamp will illuminate in
the message center. The PCM will monitor the oil
pressure switch and signal a low oil pressure condi-
tion. A continuous four minute warning chime will
sound and the oil pressure lamp will come ON when
the following conditions are met:
²Ignition on and engine not cranking
8B - 2 CHIME/BUZZERRS
CHIME/BUZZER (Continued)
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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)
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²Front Fog Lamp Relay Actuation
²Front and Rear Blower Motor Relay Actuation
²Accessory Relay Actuation
²Electronic Back Light (EBL) Rear Defogger
²Horn Relay Actuation
²Park Lamp Relay Actuation
²Name Brand Speaker (NBS) Relay Actuation
²Headlamp Washer Relay Actuation
²Diesel Cabin Heater (Diesel Engine Vehicles)
The following inputs areReceived/Monitoredby
the Front Control Module:
²B+ Connection Detection
²Ambient Temperature Sensing
²Right/Left Park Lamp Outage
²Ignition Switch Start Only
²Ignition Switch Run and Start Only
²Washer Fluid Level
²Windshield Wiper Park
²Brake Fluid Level
²Back-Up switch
²Stop Lamp Sense
²Engine Crank Signal (Diesel Engine Vehicles)
²Horn Input
DIAGNOSIS AND TESTING - FRONT CONTROL
MODULE
The front control module is a printed circuit board
based module with a on-board micro-processor. The
front control module interfaces with other electronic
modules in the vehicle via the Programmable Com-
munications Interface (PCI) data bus (J1850). In
order to obtain conclusive testing the Programmable
Communications Interface (PCI) data bus network
and all of the electronic modules that provide inputs
to, or receive outputs from the front control module
must be checked. All PCI (J1850) communication
faults must be resolved prior to further diagnosing
any front control module related issues.
The front control module was designed to be diag-
nosed with an appropriate diagnostic scan tool, such
as the DRB IIIt. The most reliable, efficient, and
accurate means to diagnose the front control module
requires the use of a DRB IIItscan tool and the
proper Body Diagnostic Procedures manual.
Before any testing of the front control module is
attempted, the battery should be fully charged and
all wire harness and ground connections inspected
around the affected areas on the vehicle.
REMOVAL
(1) Disconnect the positive and negative battery
cables from the battery.
(2) Remove the battery from the vehicle. Refer to
the procedure in Battery Systems.(3) Using a long flat-pladed screwdriver, gently
twist the Intelligent Power Module (IPM) retaining
clip outboard to free the intelligent power module
from its mounting bracket (Fig. 6). Rotate intelligent
power module upward to access the Front Control
Module (FCM) retaining screws.
(4) Remove the front control module retaining
screws.
(5) Using both hands, pull the front control module
straight from the intelligent power module assembly
to disconnect the 49-way electrical connector (Fig. 7)
and remove the front control module from the vehi-
cle.
INSTALLATION
(1) Install the front control module in the intelli-
gent power module assembly by pushing the 49-way
electrical connector straight in (Fig. 7).
(2) Install the front control module retaining
screws. Torque the screws to 7 in. lbs.
(3) Rotate the intelligent power module assembly
downward to secure in mounting bracket.
(4) Install the battery in the vehicle. Refer to the
procedure in Battery Systems.
(5) Connect the positive and negative battery
cables.
NOTE: If the vehicle is not equipped with Name
Brand Speakers (NBS, Infinity) or Headlamp Wash-
ers the DRB IIITmust be used to Disable the appro-
priate relays in the Intelligent Power Module
Assembly.
Fig. 6 REMOVING INTELLIGENT POWER MODULE
8E - 6 ELECTRONIC CONTROL MODULESRS
FRONT CONTROL MODULE (Continued)
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PCM determines basic fuel injector pulse width from
this input.
²The PCM determines atmospheric air pressure
from the MAP sensor input to modify injector pulse
width.
When the key is in the ON position and the engine
is not running (zero rpm), the Auto Shutdown (ASD)
and fuel pump relays de-energize after approximately
1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
ENGINE START-UP MODE
This is an OPEN LOOP mode. If the vehicle is in
park or neutral (automatic transaxles) or the clutch
pedal is depressed (manual transaxles) the ignition
switch energizes the starter relay. The following
actions occur when the starter motor is engaged.
²If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the Auto Shutdown (ASD) relay and fuel pump relay.
If the PCM does not receive both signals within
approximately one second, it will not energize the
ASD relay and fuel pump relay. The ASD and fuel
pump relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil and heated oxygen sen-
sors.
²The PCM energizes the injectors (on the 69É
degree falling edge) for a calculated pulse width until
it determines crankshaft position from the camshaft
position sensor and crankshaft position sensor sig-
nals. The PCM determines crankshaft position within
1 engine revolution.
²After determining crankshaft position, the PCM
begins energizing the injectors in sequence. It adjusts
injector pulse width and controls injector synchroni-
zation by turning the individual ground paths to the
injectors On and Off.
²When the engine idles within664 RPM of its
target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode.
Once the ASD and fuel pump relays have been
energized, the PCM determines injector pulse width
based on the following:
²Battery voltage
²Engine coolant temperature
²Engine RPM
²Inlet/Intake air temperature (IAT)
²MAP
²Throttle position
²The number of engine revolutions since cranking
was initiated
During Start-up the PCM maintains ignition tim-
ing at 9É BTDC.
ENGINE WARM-UP MODE
This is an OPEN LOOP mode. The following inputs
are received by the PCM:
²Engine coolant temperature
²Manifold Absolute Pressure (MAP)
²Inlet/Intake air temperature (IAT)
²Crankshaft position (engine speed)
²Camshaft position
²Knock sensor
²Throttle position
²A/C switch
²Battery voltage
²Vehicle speed
²Speed control
²O2 sensors
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts ignition timing and engine idle
speed. Engine idle speed is adjusted through the idle
air control motor.
CRUISE OR IDLE MODE
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising or idle
the following inputs are received by the PCM:
²Inlet/Intake air temperature
²Engine coolant temperature
²Manifold absolute pressure
²Crankshaft position (engine speed)
²Camshaft position
²Knock sensor
²Throttle position
²Exhaust gas oxygen content
²A/C control positions
²Battery voltage
²Vehicle speed
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts engine idle speed and ignition
timing. The PCM adjusts the air/fuel ratio according
to the oxygen content in the exhaust gas (measured
by the upstream and downstream heated oxygen sen-
sor).
The PCM monitors for engine misfire. During
active misfire and depending on the severity, the
PCM either continuously illuminates or flashes the
malfunction indicator lamp (Check Engine light on
instrument panel). Also, the PCM stores an engine
misfire DTC in memory.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
8E - 20 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)
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