1993 CHEVROLET PLYMOUTH ACCLAIM coolant temperature

sends the message to the Engine Controller. The En-
gine Controller turns on the fan through the fan re-
lay. See Wiring Diagrams Manual for circuity and
diagnostics provided.Switching through the Engine Controller provides
fan control for the following conditions.
² The fan will not run during cranking until the en-
gine starts no matter what the coolant temperature
is.
² Fan will run when the air conditioning clutch is
engaged and low pressure cutout switch is closed.
² For 4 cylinder application the fan will run at ve-
hicle speeds above about 40 mph only if coolant tem-
perature reaches 110ÉC (230ÉF). It will turn off when
the temperature drops to 104ÉC (220ÉF). At speeds
below 40 mph the fan switches on at 102ÉC (215ÉF)
and off at 93ÉC (200ÉF).
² This is to help prevent steaming. The fan will run
only below 16ÉC (60ÉF) ambient. Between 38ÉC
(100ÉF) to 97ÉC (195ÉF) coolant temperature, at idle
and then only for three minutes.
RADIATOR FAN CONTROLÐAC/AY BODY V-6 ONLY
For this application, fan control is accomplished
based on coolant temperature, and on A/C head pres-
sure. These vehicles receive the variable displace-
ment compressor. The fan will go on when;
² Coolant temperature reaches 102ÉC (215ÉF) and off
at 93.4ÉC (200ÉF) regardless of vehicle speed.
² When the head pressure reaches 1516.9 kPa (220
psi) and turn off when the pressure reaches 1103 kPa
(160 psi).
TEMPERATURE GAUGE INDICATION
At idle the temperature gauge will rise slowly to
about 5/8 gauge travel. The fan will come on and the
gauge will drop to about 1/2 gauge travel, this is nor-
mal.
ELECTRIC FAN MOTOR
To check out the electric fan motor, disconnect the
fan motor wire connector and connect it with #14
gauge wires to a good 12-volt battery observing cor-
rect polarity per (Fig. 14). If the fan runs normally,
the motor is functioning properly. If not, replace fan
module using the removal and installation instruc-
tions contained in the Fan Section. If the motor is
noticeably overheated (i.e.; wire insulation melted,
motor charred) the system voltage may be too high.
Check charging system, see Group 8A, Battery/Start-
ing/Charging System Diagnostics.
ELECTRIC FAN MOTOR TEST
Equipment required
² Diagnostic Tool DRB II or equivalent
² Volt/Ohm Meter
² Wiring Diagram Manual (1) Run the engine to normal operating tempera-
ture. (2) Check wiring connector in C25, C9, and C26 for
proper engagement, see Wiring Diagram Manual (3) Using a diagnostic tool, plugged into the diag-
nostic connector rearward of the battery, check the
On-Board Diagnostics (OBD) in the Engine Control-
ler for fault codes, see Group 14, Fuel Injection for
instructions. (4) If fault code 88-12-35-55 is detected, proceed to
Step 5. (5) With the ignition switch in the run position,
test for battery voltage (single pin connector) at the
fan relay. Voltage reading OK, proceed to Step 6a.
Voltage at 0-1 volt, proceed to Step 6b. 6(a) With the ignition off, disconnect the 60-way
connector from the Engine Controller (outboard of
battery) and return the ignition to the run position.
Test for battery voltage at cavity 31 of the 60-way
connector (Fig. 15). Voltage reading OK and female
terminal is not damaged, replace the Engine Control-
ler. Voltage reading 0, repair open or short in C27
circuit. (b) With the ignition off, disconnect the 60-way
connector from the Engine Controller (outboard of
battery) and return the ignition to the run position.
Test for battery voltage at the single pin connector
at the fan relay. Voltage reading OK, replace the
Engine Controller. Voltage reading 0-1 volt, pro-
ceed to Step 7.
(7) With ignition in the run position, test for bat-
tery voltage at the wire (C27) in the 3-way connector
of the fan relay. Voltage reading OK, replace the fan
relay. Voltage reading 0, repair open or short in C27
circuit. (8) Turn ignition off, connect the 60-way connector
at the Engine Controller and test the system.
Fig. 14 Electric Fan MotorÐTypical
7 - 22 COOLING SYSTEM Ä

ENGINE BLOCK HEATER
DESCRIPTION AND OPERATION
On all models an engine block heater is available as
an optional accessory. The heater, operated by ordinary
house current (110 Volt A.C.) through a power cord and
connector behind the radiator grille, provides easier
engine starting and faster warm-up when vehicle is
operated in areas having extremely low temperatures.
The heater is mounted in a core hole (in place of a core
hole plug) in the engine block, with the heating ele-
ment immersed in coolant (Fig. 9). The power cord must be secured in its retainer
clips, and not positioned so it could contact link-
ages or exhaust manifolds and become damaged. If unit does not operate, trouble can be in either the
power cord or the heater element. Test power cord for
continuity with a 110-volt voltmeter or 110-volt test
light; test heater element continuity with an ohmmeter
or 12-volt test light.
REMOVAL
(1) Drain coolant from radiator and cylinder block.
Refer to Cooling System Drain, Clean, Flush and Re-
fill of this section for procedure. (2) Detach power cord plug from heater.
(3) Loosen screw in center of heater. Remove
heater assembly.
INSTALLATION
(1) Thoroughly clean core hole and heater seat.
(2) Insert heater assembly with element loop posi-
tioned upward.
(3) With heater seated, tighten center screw se-
curely to assure a positive seal. (4) Fill cooling system with coolant to the proper
level, vent air, and inspect for leaks. Pressurize sys-
tem with Radiator Pressure Tool before looking for
leaks.
Fig. 9 Engine Block Heater
7 - 28 COOLING SYSTEM Ä

² To set DAY of WEEK, press TIME button. An ar-
row will appear on the display and point to the Day.
Press and hold the SET button to move the day for-
ward or INFO button to move it backward.
² To set DAY of MONTH, press TIME button. The
arrow will point to Date. Press and hold the SET
button to advance the date or INFO button to move
it backwards.
² To set MONTH of YEAR, press TIME button. The
arrow will point to the Month. Press and hold the
SET button to advance the Month forward or INFO
button to move backward. TEMP button, pressing the Temp button will dis-
play:
² The temperature outside the vehicle
² Vehicle direction define by an eight point compass
If Compass has lost calibration or not receiving
good information from the engine compartment node,
an asterisk (*) will flash on the display and the word
calibrate will appear. Refer to Compass Calibration. FUEL BUTTON, WILL DISPLAY:
² Pressing FUEL button the first time will show, the
estimated number of miles that can be driven with
the remaining fuel. The destination to empty indica-
tion will vary every few seconds as the amount of
fuel and fuel efficiency is calculated. This function
can not be reset.
² Pressing the FUEL button second time; will dis-
play the fuel consumed.
²
Pressing the FUEL button third time; will display
the average fuel economy in miles per gallon since last
reset. The display will be updated every 16 seconds.
² Pressing the FUEL button forth time, the current
fuel economy will be displayed. The current fuel
economy will be up updated every two seconds.
² To reset Fuel consumed, press SET button until
the fuel consumed message is displayed and then
within five seconds press SET button.
² To reset AVERAGE FUEL ECONOMY, press the
FUEL button until average fuel economy is displayed
and within five seconds press SET button. TRIP RESET, press FUEL button and wait four
seconds press the SET button twice. This clears all
trip information and the message Trip Reset will be
displayed. This will occur only if a reset function is
currently being displayed. The reset functions:
² Fuel consumed
² Average fuel economy message
INFO button, will active a MONITORED SYS-
TEMS OK message on display if all monitored sys-
tems are operating properly. If a problem is detected,
the appropriate message will be displayed. SET button, will clear the various functions after
they have been displayed. It is used to enter the
clock set or compass variance modes. This button is
also used to reset certain trip computer functions and
the maintenance reminder message.
The EVIC display may be turned off by pressing the
TIME and SET buttons at the same time. Pressing the
buttons a second time will restore the display.
EVIC INFORMATION SOURCES
The EVIC monitors information provided by the
body controller, engine compartment node and pow-
ertrain control module. Refer to Body Diagnostic Test
Procedure Manual for test procedures. The Body Controller is a micro-controller unit
which, informs the EVIC overhead console via the
CCD bus of:
² Time of day
² Day of week
² Day of month
² Month of year
² Fuel range
² Fuel consumed
² Fuel efficiency
² Warning messages as noted in Fig. 2
The Engine Compartment Node is a microcomputer
controlled unit which, informs the EVIC overhead
console via the CCD bus of:
² Outside temperature
² Compass direction
THE FOLLOWING ARE WARNING MESSAGES:
² Low brake fluid
² Low coolant level
² Low engine oil level
The powertrain control module is a microcomputer
controlled unit which, informs the EVIC overhead con-
sole via the CCD bus of the following warning messages:
² Engine temperature high
² Voltage improper
Fig. 2 EVIC Messages and Sensors
Ä OVERHEAD CONSOLE 8C - 7

dition exists. These messages are displayed on the
center of the instrument panel.For complete EVIC operating instructions, refer to
the Owners Manual provided with the vehicle.
EVIC BUTTON FUNCTIONS
TIME button will display:
² Time of day
² Day of week
² Day of month
² Month of year
² To set HOURS, press TIME button and within four
seconds press the SET button. An arrow will appear
on the display and point to the hours. Press and hold
the SET button to advance the hours or INFO button
to set back the hours.
² To set MINUTES, press TIME button. The arrow
will point to the minutes. Press and hold the SET
button to advance the minutes or INFO button to set
back the minutes.
² To set DAY of WEEK, press TIME button. An ar-
row will appear on the display and point to the Day.
Press and hold the SET button to move the day for-
ward or INFO button to move it backward.
² To set DAY of MONTH, press TIME button. The
arrow will point to Date. Press and hold the SET
button to advance the date or INFO button to move
it backwards.
² To set MONTH of YEAR, press TIME button. The
arrow will point to the Month. Press and hold the
SET button to advance the Month forward or INFO
button to move backward. TEMP button, pressing the Temp button will dis-
play:
² The temperature outside the vehicle
² Vehicle direction define by an eight point compass
If Compass has lost calibration or not receiving
good information from the engine compartment node,
an asterisk (*) will flash on the display and the word
calibrate will appear. Refer to Compass Calibration. FUEL BUTTON, WILL DISPLAY:
² Pressing FUEL button the first time will show, the
estimated number of miles that can be driven with
the remaining fuel. The destination to empty indica-
tion will vary every few seconds as the amount of
fuel and fuel efficiency is calculated. This function
can not be reset.
² Pressing the FUEL button second time; will dis-
play the fuel consumed.
² Pressing the FUEL button third time; will display
the average fuel economy in miles per gallon since
last reset. The display will be updated every 16 sec-
onds.
² Pressing the FUEL button forth time, the current
fuel economy will be displayed. The current fuel
economy will be up updated every two seconds. ²
To reset Fuel consumed, press SET button until
the fuel consumed message is displayed and then
within five seconds press SET button.
² To reset AVERAGE FUEL ECONOMY, press the
FUEL button until average fuel economy is displayed
and within five seconds press SET button. TRIP RESET, press FUEL button and wait four
seconds press the SET button twice. This clears all
trip information and the message Trip Reset will be
displayed. This will occur only if a reset function is
currently being displayed. The reset functions:
² Fuel consumed
² Average fuel economy message
INFO button, will active a MONITORED SYS-
TEMS OK message on display if all monitored sys-
tems are operating properly. If a problem is detected,
the appropriate message will be displayed. SET button, will clear the various functions after
they have been displayed. It is used to enter the
clock set or compass variance modes. This button is
also used to reset certain trip computer functions and
the maintenance reminder message. The EVIC display may be turned off by pressing
the TIME and SET buttons at the same time. Press-
ing the buttons a second time will restore the dis-
play.
EVIC INFORMATION SOURCES
The EVIC monitors information provided by the
body controller, engine compartment node and pow-
ertrain control module. Refer to Body Diagnostic Test
Procedure Manual for test procedures. The Body Controller is a micro-controller unit
which, informs the EVIC via the CCD bus of:
² Time of day
² Day of week
² Day of month
² Month of year
² Fuel range
² Fuel consumed
² Fuel efficiency
² Warning messages as noted in Fig. 3.
The Engine Compartment Node is a microcomputer
controlled unit which, informs the EVIC via the CCD
bus of:
² Outside temperature
² Compass direction
THE FOLLOWING ARE WARNING MESSAGES:
² Low brake fluid
² Low coolant level
² Low engine oil level
The powertrain control module is a microcomputer
controlled unit which, informs the EVIC via the CCD
bus of the following warning messages:
² Engine temperature high
² Voltage improper
8C - 14 OVERHEAD CONSOLE Ä

VISUAL MESSAGES
Following are the visual messages and the condi-
tions under which, the messages will be given:
² Keys in ignition
² Exterior lamps on
These messages will appear if the conditions are
present and the driver's door is open while the igni-
tion switch is in the OFF, LOCK, or ACC positions.
A tone will sound until the condition is corrected or
the door is closed.
² Passenger door ajar
² Driver door ajar
² Trunk ajar
² Park brake engaged
² Right rear door ajar
² Left rear door ajar
These messages will appear if a condition is de-
tected after the vehicle is in motion. When the con-
dition is corrected, a short tone will sound to
acknowledge the action. LOW OIL PRESSURE
If this message is displayed while the vehicle is at
cruising speeds, immediate attention is required. If
this message appears at idle speed, increase the idle
speed and the message should go off. If the message
remains on, immediate attention is required. ENGINE TEMP CRITICAL
This message appears when a sensor has deter-
mined that the engine coolant is overheating. If this
message comes on and stays on, immediate action is
required. COOLANT LEVEL LOW
LOW FUEL LEVEL
LOW BRAKE FLUID WASHER FLUID LOW
These messages will appear if a continuous warn-
ing condition is detected while the engine is running.
Inspection is required. To clear this message from
the display, after the condition is corrected, the igni-
tion switch must be turned OFF. CHECK TRANS
This message will appear if a continuous warning
condition is detected while the engine is running. Im-
mediate attention is recommended. To clear this mes-
sage from the display, after the condition has been
corrected, the ignition switch must be turned OFF. VOLTAGE IMPROPER
This message will appear if a continuous warning
condition is detected. Immediate attention is re-
quired. To clear this message from the display, after
the condition has been corrected, the ignition switch
must be turned OFF. TURN SIGNAL ON
This message will appear if the turn signal is left
on while vehicle speed is over 15 mph and the vehi-
cle has traveled over one-half mile. FASTEN SEAT BELTS
An intermittent chime tone will sound for several
seconds if the seat belt is not fastened. CHK ENGINE OIL LEVEL
If this message is delivered, a check of the engine
oil dipstick is suggested. To clear this message, after
the condition is corrected, the ignition switch must
be turned OFF. HEADLAMP OUT
BRAKE LAMP OUT
TAIL LAMP OUT
These conditions are monitored only when the
lamps are on. The message will remain, even after
the lamp is replaced, until the lamp is turned on and
operates. SERVICE REMINDER
The maintenance reminder statement is pro-
grammed to provide general information only. Refer
to Group 0, Lubrication & Maintenance for specific
vehicle requirements. The service reminder message is displayed at 7,500
miles or 12 months intervals, which ever comes first. MONITORED SYSTEMS OK
If there is no warning condition to report, the mes-
sage Monitored Systems OK is displayed (Fig. 3).
ENGINE COMPARTMENT NODE (ECN)
The Engine Compartment Node is a microcomputer
controlled unit which, informs the Electronic Vehicle
Information Center (EVIC) via the CCD bus of:
² Outside temperature
² Compass direction
and the following warning messages:
² Low Brake Fluid
² Low Coolant Level
² Low Engine Oil Level
Fig. 3 EVIC Messages and Sensors
Ä OVERHEAD CONSOLE 8C - 15

IGNITION SYSTEMS
CONTENTS
page page
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐDIAGNOSTIC PROCEDURES
..... 11
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNI- TION SYSTEMSÐSERVICE PROCEDURES . 14
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNI- TION SYSTEMSÐSYSTEM OPERATION .... 1
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMÐDIAGNOSTIC PROCEDURES
.... 35
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMÐSYSTEM OPERATION ......... 24
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMSÐSERVICE PROCEDURES ...... 39
IGNITION SWITCH ...................... 45
SPECIFICATIONS ....................... 47
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicles by letter designation. A chart ex-
plaining the designations appears in the Introduction
Section of this manual.
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐSYSTEM OPERATION
INDEX
page page
Auto Shutdown (ASD) Relay and Fuel Pump Relay . 8
Coolant Temperature Sensor ................. 7
Distributor Cap ........................... 1
Distributor Pick-UpÐ3.0L Engine .............. 7
Distributor Pick-UpÐPCM Input ............... 6
General Information ........................ 1 Ignition Coil
.............................. 9
Manifold Absolute Pressure (MAP) Sensor ...... 8
Powertrain Control Module (PCM) ............. 6
Rotor .................................. 2
Spark Plug Cables ........................ 2
Spark Plugs ............................. 3
GENERAL INFORMATION
This section describes the ignition systems of the
2.2L TBI, 2.5L TBI, 2.5L MPI (flexible fuel AA-body)
and 3.0L engines. The Fuel Injection sections of Group 14 explain On
Board Diagnostics. Group 0, Lubrication and Maintenance, contains
general maintenance information for ignition related
items. The Owner's Manual also contains mainte-
nance information.
DISTRIBUTOR CAP
Remove the distributor cap and inspect the inside
for flash over, cracking of carbon button, lack of
spring tension on carbon button, cracking of cap, and
burned, worn terminals (Fig. 1). Also check for bro-
ken distributor cap towers. If any of these conditions
are present the distributor cap and/or cables should
be replaced. When replacing the distributor cap, transfer cables
from the original cap to the new cap one at a time.
Ensure each cable is installed into the corresponding tower of the new cap. Fully seat the wires into the
towers. If necessary, refer to the appropriate engine
firing order diagram (Fig. 2 or Fig. 3).
Fig. 1 Distributor Cap Inspection
Ä
IGNITION SYSTEMS 8D - 1

for unleaded fuel. During combustion, fuel with
MMT coats the entire tip of the spark plug with a
rust color deposit. The rust color deposits could be
misdiagnosed as being caused by coolant in the com-
bustion chamber. MMT deposits do not affect spark
plug performance.
COLD FOULING (CARBON FOULING)
Cold fouling is sometimes referred to as carbon
fouling. The deposits that cause cold fouling are ba-
sically carbon (Fig. 7). A dry, black deposit on one or
two plugs in a set may be caused by sticking valves
or defective spark plug cables. Cold (carbon) fouling
of the entire set may be caused by a clogged air
cleaner. Cold fouling is normal after short operating periods.
The spark plugs do not reach a high enough operating
temperature during short operating periods.
WET FOULING
A spark plug that is coated with excessive wet fuel or
oil is wet fouled. In older engines, wet fouling can be
caused by worn rings or excessive cylinder wear.
Break-in fouling of new engines may occur be-
fore normal oil control is achieved. In new or
recently overhauled engines, wet fouled spark
plugs can be usually be cleaned and reinstalled.
OIL OR ASH ENCRUSTED
If one or more plugs are oil or oil ash encrusted,
engine oil is entering the combustion chambers (Fig. 8).
Evaluate the engine to determine the cause.
HIGH SPEED MISS When replacing spark plugs because of a high speed
miss condition; wide open throttle operation
should be avoided for approximately 80 km (50
miles) after installation of new plugs. This will
allow deposit shifting in the combustion chamber to
take place gradually and avoid plug destroying splash
fouling shortly after the plug change.
ELECTRODE GAP BRIDGING
Loose deposits in the combustion chamber can cause
electrode gap bridging. The deposits accumulate on the
spark plugs during continuous stop-and-go driving.
When the engine is suddenly subjected to a high torque
load, the deposits partially liquefy and bridge the gap
between the electrodes
Fig. 6 Setting Spark Plug Electrode GapÐTypical
Fig. 7 Normal Operation and Cold (Carbon) FoulingFig. 8 Oil or Ash Encrusted
8D - 4 IGNITION SYSTEMS Ä

ing, detonation and cooling system malfunctions also
can cause spark plug overheating.
SPARK PLUG SERVICE
When replacing the spark plug and coil cables,
route the cables correctly and secure them in the ap-
propriate retainers. Failure to route the cables prop-
erly can cause the radio to reproduce ignition noise,
cross ignition of the spark plugs or short circuit the
cables to ground.
SPARK PLUG REMOVAL
Always remove the spark plug cable by grasping at
the spark plug boot turning, the boot 1/2 turn and
pulling straight back in a steady motion. (1) Prior to removing the spark plug spray com-
pressed air around the spark plug hole and the area
around the spark plug. (2) Remove the spark plug using a quality socket
with a rubber or foam insert. (3) Inspect the spark plug condition. Refer to
Spark Plug Condition in this section.
SPARK PLUG GAP ADJUSTMENT Check the spark plug gap with a gap gauge. If the
gap is not correct, adjust it by bending the ground
electrode (Fig. 6).
SPARK PLUG INSTALLATION (1) To avoid cross threading, start the spark plug
into the cylinder head by hand. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.)
torque. (3) Install spark plug cables over spark plugs.
POWERTRAIN CONTROL MODULE (PCM)
The ignition system is regulated by the powertrain
control module (PCM) (Fig. 14). The PCM supplies
battery voltage to the ignition coil through the Auto
Shutdown (ASD) Relay. The PCM also controls the
ground circuit for the ignition coil. By switching the ground path for the coil on and off, the PCM adjusts
ignition timing to meet changing engine operating
conditions.
During the crank-start period the PCM advances
ignition timing a set amount. During engine opera-
tion, the amount of spark advance provided by the
PCM is determined by these input factors:
² coolant temperature
² engine RPM
² available manifold vacuum
The PCM also regulates the fuel injection system.
Refer to the Fuel Injection sections of Group 14.
DISTRIBUTOR PICK-UPÐPCM INPUT
The engine speed input is supplied to the power-
train control module (PCM) by the distributor pick-
up. The distributor pick-up is a Hall Effect device
(Fig. 15 or Fig. 16).
A shutter (sometimes referred to as an interrupter)
is attached to the distributor shaft. The shutter con-
tains four blades, one per engine cylinder. A switch
plate is mounted to the distributor housing above the
shutter. The switch plate contains the distributor
Fig. 14 Powertrain control module (PCM)
Fig. 15 DistributorÐ2.2L and 2.5L TBI Engines
Fig. 13 Spark Plug Overheating
8D - 6 IGNITION SYSTEMS Ä