heating CHEVROLET DYNASTY 1993 Service Manual

GROUP TAB LOCATOR
Introduction
0Lubrication and Maintenance
2Suspension/Driveshafts
5Brakes
6Manual Transaxle Clutch
7Cooling System
9Engine
11Exhaust System and Intake Manifold
13Frame and Bumpers
19Steering
21Transaxle
22Wheels/Tires
23Body
24Heating/Air Conditioning
Component and System Index
Service Manual Comment Forms (Rear of Manual)

COMPONENT AND SYSTEM INDEX
Name Group-page Name Group-page
BODY ................................... 23-1
AA-VEHICLE BODY COMPONENT SERVICE .......23-11
AC-VEHICLE BODY COMPONENT SERVICE .......23-37
AG-VEHICLE BODY COMPONENT SERVICE .......23-52
AJ/27-VEHICLE CONVERTIBLE BODY COMPONENT SERVICE ............................ 23-86
AJ-VEHICLE BODY COMPONENT SERVICE .......23-71
AP-VEHICLE BODY COMPONENT SERVICE .......23-97
AY-VEHICLE BODY COMPONENT SERVICE .......23-133
BODY DIAGNOSTIC PROCEDURES .............23-2
GENERAL SERVICE INFORMATION .............23-1
PAINT ................................. 23-4
POWER SUNROOF ........................ 23-6
WINDSHIELD ............................ 23-9
BRAKES ..................................5-1
ANTI-LOCK BRAKE SYSTEMÐBENDIX ANTI-LOCK 10 AC/Y BODY ......................... 5-72
ANTI-LOCK BRAKE SYSTEMÐBENDIX ANTI-LOCK 6 AA,AG,AJ,AP BODY .................... 5-113
BRAKE DISC (ROTOR) ...................... 5-53
BRAKE SUPPORT ASSEMBLY .................5-25
FRONT DISC BRAKES ...................... 5-31
GENERAL INFORMATION .....................5-1
HYDRAULIC SYSTEM CONTROL VALVES .........5-26
KELSEY HAYES DOUBLE PIN FAMILY CALIPER .....5-35
KELSEY HAYES DOUBLE PIN NON-FAMILY CALIPER ............................. 5-38
MASTER CYLINDER ....................... 5-66
PARKING BRAKES ........................ 5-57
POWER BRAKES ......................... 5-68
REAR DISC BRAKES ....................... 5-45
REAR WHEEL DRUM BRAKES ................5-18
SERVICE ADJUSTMENTS .....................5-4
WHEEL BEARINGS ........................ 5-70
WHEEL CYLINDERS ....................... 5-23
COOLING SYSTEM ...........................7-1
ACCESSORY DRIVE BELTS ................... 7-24
ENGINE BLOCK HEATER .................... 7-28
GENERAL INFORMATION .....................7-1
SERVICE PROCEDURES ..................... 7-10
SPECIFICATIONS ......................... 7-29
ENGINE ..................................9-1
2.2/2.5L ENGINES .........................9-8
3.0L ENGINE ............................ 9-66
3.3/3.8L ENGINE ......................... 9-98
STANDARD SERVICE PROCEDURES .............9-1
EXHAUST SYSTEM AND INTAKE MANIFOLD .........11-1
GENERAL INFORMATION .................... 11-1
SERVICE PROCEDURES ..................... 11-4
TORQUE SPECIFICATION ................... 11-25
FRAME AND BUMPERS ....................... 13-1
BUMPER AND FASCIA ...................... 13-1
FRAME ................................ 13-9
HEATING AND AIR CONDITIONING ...............24-1
AUTOMATIC TEMPERATURE CONTROL (ATC) .....24-66 COMPONENT SERVICE PROCEDURES
..........24-47
FIXED DISPLACEMENT COMPRESSORÐMODEL 10PA17............................. 24-24
FIXED DISPLACEMENT COMPRESSORÐMODEL SD709P ............................. 24-38
FIXED DISPLACEMENT COMPRESSORÐMODEL TR105 .............................. 24-32
GENERAL INFORMATION .................... 24-1
HEATER AND A/C PERFORMANCE TESTS .........24-6
REFRIGERANT SERVICE PROCEDURES ..........24-8
VACUUM CONTROL SYSTEM DIAGNOSIS .........24-4
VARIABLE DISPLACEMENT COMPRESSORÐMODEL 6C17 ............................... 24-13
INTRODUCTION .......................... Intro.-1
LUBRICATION AND MAINTENANCE ................0-1
CHASSIS AND BODY ....................... 0-19
DRIVETRAIN ............................ 0-16
ENGINE ................................0-8
GENERAL INFORMATION .....................0-1
MANUAL TRANSAXLE CLUTCH ...................6-1
STEERING ................................ 19-1
ACUSTAR STANDARD AND TILT STEERING COLUMN ............................ 19-28
AUTOMATIC TRANSMISSION SHIFTER/IGNITION INTERLOCK .......................... 19-36
GENERAL INFORMATION .................... 19-1
POWER STEERING GEAR ................... 19-25
POWER STEERING PUMPS ..................19-1
SPECIFICATIONS AND TIGHTENING REFERENCE . . . 19-42
SUSPENSION AND DRIVESHAFTS .................2-1
AUTOMATIC AIR LOAD LEVELING SYSTEM ........2-59
AUTOMATIC AIR SUSPENSION ................2-73
DRIVESHAFTS ........................... 2-25
FRONT SUSPENSION .......................2-2
FRONT SUSPENSION SERVICE PROCEDURES .......2-5
GENERAL INFORMATION .....................2-1
REAR (STUB) AXLE ALIGNMENT ALL MODELS .....2-89
REAR SUSPENSION ....................... 2-50
SPECIFICATIONS ......................... 2-91
TRANSAXLE .............................. 21-85
41TE FOUR SPEED AUTOMATIC TRANSAXLE ......21-85
41TE FOUR SPEED TRANSAXLE HYDRAULIC SCHEMATICS ........................ 21-170
41TE ON-BOARD DIAGNOSTICS .............21-145
A-523, A-543, and A-568 MANUAL TRANSAXLE ....21-1
SPECIFICATIONS ........................ 21-183
THREE SPEED TORQUEFLITE AUTOMATIC TRANSAXLE .......................... 21-35
THREE SPEED TRANSAXLE HYDRAULIC SCHEMATICS ........................ 21-162
WHEELSÐTIRES ........................... 22-1
SPECIFICATIONS ......................... 22-8
TIRE SERVICE PROCEDURES .................22-1
WHEELS SERVICE PROCEDURES ..............22-6

FRONT SUSPENSION SERVICE PROCEDURES INDEX
page page
Ball Joints .............................. 13
Hub and Bearing Assembly ................. 20
Knuckle (Front Suspension) ................. 16
Lower Control Arm ....................... 10
Lower Control Arm Pivot Bushings ........... 11 Shock Absorbers (Strut Damper)
............. 10
Strut Damper Assembly ..................... 7
Suspension Coil Springs .................... 9
Sway Bar .............................. 14
Wheel Alignment .......................... 5
WHEEL ALIGNMENT
Front wheel alignment is the proper adjustment of
all interrelated front suspension angles. These angles
are what affects the running and steering of the
front wheels of the vehicle. The method of checking front alignment will vary
depending on the type of equipment being used. The
instructions furnished by the manufacturer of the
equipment should always be followed. With the ex-
ception that the alignment specifications recom-
mended by Chrysler Corporation be used. There are six basic factors which are the founda-
tion to front wheel alignment. These are height,
caster, camber, toe-in, steering axis inclination and
toe-out on turns. Of the six basic factors only camber
and toe in are mechanically adjustable (Fig. 1)
CAUTION: Do not attempt to modify any suspen-
sion or steering components by heating or bending
of the component.
Wheel alignment adjustments and checks should be
made in the following sequence. (1) Camber
(2) Toe
Camber is the number of degrees the top of the
wheel is tilted inward or outward from true vertical.
Inward tilt is negative camber. Outward tilt is posi-
tive camber. Excessive camber is a tire wear factor: negative
camber causes wear on the inside of the tire, while
positive camber causes wear to the outside. Toe
is measured in degrees or inches and is the
distance the front edges of the tires are closer (or far-
ther apart) than the rear edges. See Front Wheel
Drive Specifications for Toesettings.
PRE-ALIGNMENT
Before any attempt is made to change or correct
the wheel alignment factors. The following inspection
and necessary corrections must be made on those
parts which influence the steering of the vehicle. (1) Check and inflate tires to recommended pres-
sure. All tires should be the same size and in good
condition and have approximately the same wear.
Note type of tread wear which will aid in diagnosing,
see Wheels and Tires, Group 22. (2) Check front wheel and tire assembly for radial
runout. (3) Inspect lower ball joints and all steering link-
age for looseness. (4) Check for broken or sagged front and rear
springs. Front suspension must only be checked after the
vehicle has had the following checked or adjusted.
Tires set to recommended pressures, full tank of fuel,
no passenger or luggage compartment load and is on
a level floor or alignment rack. Just prior to each alignment reading. The vehicle
should be bounced (rear first, then front) by grasping
bumper at center and jouncing each end an equal
number of times. Always release bumpers at bottom
of down cycle.
Ä SUSPENSION AND DRIVESHAFTS 2 - 5

If old springs have overheated or are damaged, re-
place. Overheating indications are paint discoloration
or distorted end coils. Varga brake springs are not
painted but overheating of the brake springs will be
noted by any Blueing of the springs.
BRAKE SHOE INSTALLATION
Lubricate the eight shoe contact areas on the sup-
port plate and anchor using Mopar Multi-Purpose
Lubricant or equivalent (Fig. 11).
KELSEY HAYES REASSEMBLE
Assemble the park brake lever and wave washer to
the new replacement shoe (Fig. 9). Attach upper return spring between the two new
shoe assemblies. Apply a small amount of Mopar Multi-Purpose Lu-
bricant or equivalent to the automatic adjuster screw
assembly. Install adjuster with the two stepped forks
facing toward the outboard side of the shoes (Fig.
10). The longer fork will be pointing to the rear. Connect the lower shoe to shoe spring. Expand the automatic adjuster so that the end of the
shoes will clear the wheel cylinder boots. Position the
brake shoe assemblies on support plate and install
holddown springs (Fig. 7). Install self adjuster lever and spring.
Connect park brake cable.
Adjust brake shoes so that they will not interfere
with the drum installation.
CAUTION: Make sure the adjuster screw nut contacts
the adjuster tubular strut.
Install the drums and pump the brake pedal
several times to partially complete the shoe ad-
justment. After adjusting the Parking brake cable (see Adjust-
ing Parking Brake), road test vehicle. The automatic
adjuster will continue the brake adjustment during the
test.
VARGA REASSEMBLE
(1) Install park brake cable in park brake lever of
trailing shoe. (2) Attach trailing shoe, then leading shoe lower
springs to shoes and anchor plate. (3) Position shoes on support plate and install hold-
down springs. (4) Install automatic adjusters. Left side adjuster
has left hand threads and right side adjuster has
right-hand threads. Do not interchange sides.
Make sure adjuster is installed correctly. (Adjuster
ends must be above extruded pins in web of shoe as
shown in Fig. 3). (5) Install upper shoe to shoe spring. Ensure that
the spring terminal ends are fully engaged in the shoe
webs. (6) Rotate serrated adjuster nut to remove free play
from the adjuster assembly. (7) Install the adjuster lever on the leading shoe
pivot pin. Then attach the short end of the adjuster
spring into the hole on the lever. Then install the long
end of the spring in the leading shoe hole. (8) Connect park brake cable and adjust brake shoes
so as not to interfere with drum installation.
BRAKE DRUM REFACING
Measure drum runout and diameter. If not to speci-
fication, reface drum. (Runout should not exceed
0.1524 mm or 0.006 inch). The diameter variation (oval
shape) of the drum braking surface must not exceed
either 0.0635 mm (0.0025 inch) in 30É or 0.0889 mm
(0.0035 inch) in 360É. All drums will show markings of maximum allowable
diameter (Fig. 12).
Fig. 10 Adjuster Screw and Lever (Typical)
Fig. 11 Shoe Contact Areas on Support Plate
Ä BRAKES 5 - 21

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

GENERATOR INDEX
page page
General Information ........................ 9
Generator ReplacementÐ2.2L Turbo Engine (With 16 Valve Cylinder Head) ............. 10 Generator ReplacementÐ2.2L/2.5L Engine
...... 9
Generator ReplacementÐ3.0L Engine ......... 10
Generator ReplacementÐ3.3L/3.8L Engine ..... 11
GENERAL INFORMATION
This section will cover generator removal and instal-
lation only. Information covering generator on-vehicle
testing and diagnosis can be found in Group 8A,
Battery/Starting/Charging Systems Diagnostics. To
identify the generator, refer to the Generator Specifi-
cation chart at the rear of this section. These generators are not intended to be disas-
sembled for service. It must be replaced as an
assembly.
GENERATOR REPLACEMENTÐ2.2L/2.5L ENGINE
Removal and repositioning of A/C compressor (with-
out disconnecting refrigerant lines) is necessary on
some models to gain access to generator. (1) Disconnect battery negative cable (Fig. 1).
(2) If Equipped With Air Conditioning:
(a) Remove the A/C drive belt. Refer to Group 7,
Cooling System. (b) Remove the four bolts retaining the A/C com-
pressor to the mounting bracket (Fig. 2). (c) Without disconnecting the A/C refrigerant
lines, position the A/C compressor to allow generator
removal.
WARNING: THE A/C REFRIGERANT SYSTEM IS UN-
DER PRESSURE EVEN WHEN THE ENGINE IS OFF.
REFER TO THE SAFETY PRECAUTIONS AND WARN-
INGS SECTION IN HEATING AND A/C, GROUP 24,
BEFORE PERFORMING ANY SERVICE OPERATION. (3) Remove the generator drive belt. Refer to Group
7, Cooling System. (4) Remove the two generator mounting bolts (Fig.
3) and position the generator to gain access to all the
wire connectors. If equipped with:
² BOSCH GENERATOR: Remove B+ terminal nut,
field terminal nuts, and ground harness hold down
nuts (Fig. 4). Remove wire connector assembly.
² NIPPONDENSO GENERATOR: Remove nuts
from field terminals, ground terminal, wire harness
Fig. 1 Remove Battery Negative (-) Cable
Fig. 2 A/C Compressor ReplacementÐ2.2 L/2.5 L Engine
Fig. 3 Remove/Install Generator
Ä BATTERY/STARTER/GENERATOR SERVICE 8B - 9

and B+ terminal (Fig. 5). B+ terminal nut must be
removed last to prevent damage to terminal insula-
tor. (5) Remove the generator from the vehicle.
(6) For installation, reverse above procedures.
Tighten all fasteners to the proper torque. Refer to
the Torque Specifications chart at the rear of this
group.
GENERATOR REPLACEMENTÐ2.2L TURBO
ENGINE (WITH 16 VALVE CYLINDER HEAD)
(1) Disconnect battery NEGATIVE cable (Fig. 1).
(2) Remove generator/air conditioning drive belt.
Refer to Group 7, Cooling System. (3) Remove the bolts retaining the A/C compressor
to the mounting bracket. (4) Without disconnecting the A/C refrigerant
lines, position the A/C compressor to allow generator
removal. WARNING: THE A/C REFRIGERANT SYSTEM IS UN-
DER PRESSURE EVEN WHEN THE ENGINE IS OFF.
REFER TO THE SAFETY PRECAUTIONS AND
WARNINGS SECTION IN HEATING AND A/C,
GROUP 24, BEFORE PERFORMING ANY SERVICE
OPERATION.
(5) Remove the generator mounting bracket bolts
and separate generator from mounting bracket (Fig.
6).
(6) Remove the B+ terminal nut, field terminal
nuts, and ground/wire harness hold-down nuts. Re-
move wire connectors. (7) Remove the generator from the vehicle.
(8) For installation, reverse above procedures.
Tighten all fasteners to the proper torque. Refer to
the Torque Specifications chart at the rear of this
group.
GENERATOR REPLACEMENTÐ3.0L ENGINE
(1) Disconnect battery negative cable (Fig. 1).
(2) Remove generator drive belt. Refer to Group 7,
Cooling System. (3) Remove the generator mounting bolts and sep-
arate the generator from the mounting bracket (Fig.
7). (4) Remove the B+ terminal nut, field terminal
nuts, and ground/wire harness hold-down nuts. Re-
move wire connectors. (5) Remove the generator from the vehicle.
Fig. 4 Remove or Install Wire Connector AssemblyÐBosch Generator
Fig. 5 Remove or Install Wire ConnectorAssemblyÐNippondenso Generator
Fig. 6 Generator MountingÐ2.2 L Turbo Engine With 16 Valve Cylinder Head
8B - 10 BATTERY/STARTER/GENERATOR SERVICE 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 determined
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 programmed
to provide general information only. Refer to Group 0,
Lubrication & Maintenance for specific vehicle require-
ments.
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. 2).
AUTOMATIC CALIBRATION SET PROCEDURE
The engine compartment node will continuously
and automatically recalibrate the compass under nor-
mal driving conditions. As long as the vehicle is
turning, the engine compartment node will record
new compass data. This new data will be used to
recalibrate the compass at a rate of at least once per
full (360 degree) turn of the vehicle. Automatic cali-
bration does not require operator interface.
MANUAL CALIBRATION SET PROCEDURE
Manual compass calibration has been replaced by
automatic calibration set procedure. The manual cal-
ibration set procedure is available, but no longer
serves any useful purpose.
EVIC SELF CHECK DIAGNOSTICS
Ignition switch ON, the EVIC not displaying any
message, may imply a system failure and not an
EVIC failure. Turn the ignition OFF, close all vehi-
cle doors and wait at least 60 seconds before begin-
ning test. Turn ignition switch to the ON position.
Pressing the TEMP, FUEL and INFO buttons at the
same time shall provide the visual message MOD-
ULE SELF CHECK for two seconds. Following at
two second interval there will be messages:
² E2-0 SELF CHECK
² E3-0 SELF CHECK
² END OF SELF CHECK
Showing the microcomputer is working properly.
When the self check mode and message shows:
² E2-1
² E3-2
This would show a fault exists in the EVIC's micro-
computer and the EVIC should be replaced (Fig. 3).
8C - 8 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

(Fig. 9). This short circuits the electrodes. Spark
plugs with electrode gap bridging can be cleaned us-
ing standard procedures.
SCAVENGER DEPOSITS Fuel scavenger deposits may be either white or yel-
low (Fig. 10). They may appear to be harmful, but
are a normal condition caused by chemical additives
in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Accumulation on the
ground electrode and shell area may be heavy but
the deposits are easily removed. Spark plugs with
scavenger deposits can be considered normal in con-
dition and be cleaned using standard procedures.
CHIPPED ELECTRODE INSULATOR A chipped electrode insulator usually results from
bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,
severe detonation also can separate the insulator
from the center electrode (Fig. 11). Replace spark
plugs with chipped electrode insulators. PREIGNITION DAMAGE
Excessive combustion chamber temperature can
cause preignition damage. The center electrode dis-
solves first and the ground electrode dissolves some-
what later (Fig. 12). Insulators appear relatively
deposit free. Determine if the spark plug has the cor-
rect heat range rating for the engine, if ignition tim-
ing is over advanced or if other operating conditions
are causing engine overheating. The heat range rat-
ing refers to the operating temperature of a particu-
lar type spark plug. Spark plugs are designed to
operate within specific temperature ranges depend-
ing upon the thickness and length of the center elec-
trode and porcelain insulator.
SPARK PLUG OVERHEATING Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
13). The increase in electrode gap will be consider-
ably in excess of 0.001 in per 1000 miles of operation.
This suggests that a plug with a cooler heat range
rating should be used. Over advanced ignition tim-
Fig. 9 Electrode Gap Bridging
Fig. 10 Scavenger Deposits
Fig. 11 Chipped Electrode Insulator
Fig. 12 Preignition Damage
Ä IGNITION SYSTEMS 8D - 5