
ENGINEANDEMISSION CONTROLOVERALLSYSTEM
ECCS Component PartsLocation
EGR valve
IACV.air regulator
EGRC-BPTvalve
Injector
IACV.AAC valve
IACV.FICD solenoidvalve
Engine coolant temperature sensor
Knock sensor Pressure
regulator
Heated oxygen
sensor Camshaft
positionsensor,
ignition coiland power
transistor builtintodistributor
EC-228
SEF307R

ENGINEANDEMISSION CONTROLOVERALLSYSTEM
System Chart
Camshaft positionsensor Fuel
injection
&
mixture ratio
•
I
I
control Injectors
Mass airflow sensor
I
Distributorignitionsystem
r
~1
Power transistor
Engine coolant temperature
.
sensor
I
IACV-AAC valveand
Idle aircontrol system
IACV-FICDsolenoidvalve
Heated oxygen sensor
I
IACV-airregulator control
~--..j
IACV-air regulator
I
Ignition switch
I
I
Throttle position sensor
~-+
Fuel
pump control Fuel
pump relay
ECM
(ECCS
control
Neutral position/Inhibitor
.
module) Heatedoxygen sensor
switch monitor
&
on-board diagnos-
~-+
Malfunction
indicatorlamp
tic system (On
theinstrument panel)
I
Air conditioner switch
t~
EGRvalve
&
EVAP canister
1---+
EGR
valve
&
EVAP canister
purge control purge
control solenoid valve
Knock sensor
.....
Frontheated oxygen sensor Front
heated oxygen sensor
Battery voltage
.
heater
control heater
I
.
Power steering oilpressure
~
Coolingfancontrol
--
Cooling
fanrelay
switch
Vehicle speedsensor
.....
Airconditioning cutcontrol Air
conditioner relay
EC-232

ON-BOARDDIAGNOSTIC SYSTEMDESCRIPTION
CONSULT (Coni'd)
ECCS COMPONENT PARTS/CONTROL SYSTEMSAPPLICATION
DIAGNOSTIC TESTMODE
SELF.
Item WORKDlAG.
DATAACTIVEFUNCTION
SUPPORT NOSTICMONITOR TESTTEST
RESULTS
Camshaft positionsensor XX
Mass airflow sensor XX
Engine coolant temperature sensor XX
X
Heated oxygen sensor X
X
Vehicle speedsensor X
X
Throttle positionsensor X
XX X
INPUT Knocksensor X
lJ)
~ Ignitionswitch(startsignal) X
X
a:
<
0-
Airconditioner switch X
~
z
Park/Neutralpositionswitch X
X
w
z
0
Powersteering oilpressure switch X
X
0-
:!
X
0
Battery
voltage
0
lJ)
Injectors XX
X
0
0
X(Ignition
w
Powertransistor (Iynitiontiming) X
XX
X
signal)
IACV-AAC valve XX
XX
OUTPUT Air
conditioner relay X
Fuel pump relay XXX
X
Cooling fan X
X
X
EGR valve
&
EVAP canister purge
X
X
X
control solenoid valve
X: Applicable
EC-255
•

ON-BOARDDIAGNOSTIC SYSTEMDESCRIPTION
CONSULT (Conl'd)
ACTIVE TESTMODE
TEST ITEM CONDITION JUDGEMENTCHECKITEM(REMEDY)
• Engine: Returntothe original
•Harness andconnector
FUEL INJECTION trouble
condition
Iftrouble symptom disappears,
•Fuel injectors
• Change theamount offuel
seeCHECK ITEM.
•Heated oxygen sensor
injection usingCONSULT .
• Engine: Afterwarming up,idle
IACV-AACIV the
engine.
Enginespeedchanges according •Harness andconnector
OPENING •
Change theIACV-AAC valve
tothe opening percent. •
IACV-AAC valve
opening percentusingCON-
SULT.
• Engine: Returntothe original
•Harness andconnector
ENG COOLANT trouble
condition
Iftrouble symptom disappears, •
Engine coolant temperature
• Change theengine coolant
.
TEMP see
CHECK ITEM. sensor
temperature indicationusing
•Fuel injectors
CONSULT .
• Engine: Returntothe original
trouble condition
Iftrouble symptom disappears,
IGNITION TIMING•Timing light:Set •
Adjust initialignition timing
• Retard theignition timingusingsee
CHECK ITEM.
CONSULT.
• Engine: Afterwarming up,idle •
Harness andconnector
the engine. •
Compression
POWER
•
AIC
switch "OFF"
Enginerunsrough ordies. •
Injectors
BALANCE •
Shift lever "N" •
Power transistor
• Cut offeach injector signalone •
Spark plugs
at atime using CONSULT . •
Ignition coils
• Ignition switch:ON
•Harness andconnector
COOLING FAN•
Turn thecooling fan"ON" andCooling
fanmoves andstops.
•Cooling fanmotor
"OFF" usingCONSULT .
• Ignition switch:ON(Engine
FUEL PUMP stopped)
Fuelpump relaymakes theoper- •
Harness andconnector
RELAY •
Turn thefuel pump relay"ON"
atingsound. •
Fuel pump relay
and "OFF" usingCONSULT
and listen tooperating sound.
EGRC •
Ignition switch:ON
• Turn solenoid valve"ON"and Solenoid
valvemakes anoperat- •
Harness andconnector
SOLENOID "OFF"withtheCONSULT andingsound. •
Solenoid valve
VALVE listentooperating sound.
SELF-LEARNING •
In this test, thecoefficient ofself-learning controlmixture ratioreturns tothe original coefficient by
CONT touching
"CLEAR" onthe screen.
EC-259
•

ON-BOARDDIAGNOSTIC SYSTEMDESCRIPTION
CONSULT (Cont'd)
FUNCTION TEST
CONDITION
ITEM JUDGEMENT
CHECKITEM(REMEDY)
• Ignition switch:ON
->
START
• Start signal circuit is
tested whenengine is
started byoperating the
starter. Beforecranking,
START SIGNAL batteryvoltage andengine
Startsignal: OFF
->
ON •
Harness andconnector
CIRCUIT coolanttemperature are
•Ignition switch
displayed. During
cranking, averagebattery
voltage, massairflow
sensor outputvoltage and
cranking speedaredis-
.
played .
• Ignition switch:ON
(Engine running)
Lockedposition ON
•Harness andconnector
PW/ST SIGNAL •
Power steering circuitis
•Power steering oilpres-
CIRCUIT tested
whensteering
sureswitch
wheel isrotated fullyand
•Power steering oilpump
then settoastraight lineNeutral
position OFF
running position.
• Vehicle speedsensor cir-
•Harness andconnector
VEHICLE SPEED cuitistested whenvehicle Vehiclespeedsensor inputsignal is
•Vehicle speedsensor
SEN CKT isrunning ataspeed of10 greater than4km/h (2MPH)
•Electric speedometer
km/h (6MPH) orhigher .
• After warming up,idle the
engine. •Adjust ignition timing(by
• Ignition timingadjustment
movingcrankshaft position
is checked byreading Thetiming lightindicates thesame
IGN TIMING ADJ
ignitiontimingwithatim- valueonthe screen. sensor
ordistributor)
ing light andchecking •
Camshaft positionsensor
whether itagrees with drive
mechanism
specifications. •INJECTION SYS(Injector,
fuel pressure regulator,
harness orconnector)
• Air-fuel ratiofeedback cir- •
IGNITION SYS(Spark
cuit (injection system,igni- plug,
power transistor,
ignition coil,harness or
tion system, vacuum
connector)
MIXTURE RATIO system,
etc.)istested byHeated oxygen sensorCOUNT: More
•VACUUM SYS(Intake air
TEST examining
theheated oxy-than
5times during 10seconds
leaks)
gen sensor outputat2,000
•Heated oxygen sensorcir-
rpm under non-loaded
cuit
state. •Heated oxygen sensor
operation
• Fuel pressure highorlow
• Mass airflow sensor
EC-261
•

TROUBLEDIAGNOSIS -General Description
Symptom MatrixChart(Cont'd)
SYMPTOM
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e;
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- ECCS system
~
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1Il
11\ 18
1C 1F
1H 1R
1S1M 1J1L1K
1T
1V1N 1P1X
1Y
ECCS Camshaft
positionsensorcircuit
•
0
0
••
0
000 0
EC-289
Mass airflow sensor circuit
•••
•••
0
00
•
EC-293
Heated oxygen sensorcircuit
••
••
0
00
•
EC-362
Engine coolant temperature sensor
••• ••
•
•
0
0
0
•
EC-297
circuit
Throttle positionsensorcircuit
••
••
• •
EC-309
Incorrect fhrottleposition sensor
0
•
0
0
•
0
0
EC-272
adjustment
Vehicle speedsensor circuit
000
0
EC-314
Knock sensor circuit
00
0 0
EC-306
ECM
0
0
0
0
00000
0
00 0
EC-270
Start signal circuit
00
EC-317
Park/Neutral positionswitchcircuit
000
0
EC-357
Power steering oilpressure switchcir-
0
0
EC-354
cuit
•
• ;High Possibility Item
0;
Low Possibility Item
EC-275
(continued
onnext page)

TROUBLEDIAGNOSIS FORNON-DETECTABLE ITEMS
Exhaust GasRecirculation (EGR)Valveand
EVAP Canister PurgeControl
SYSTEM DESCRIPTION
I
Camshaft positionsensor
I
Engine speed
EGRvalve
I
Mass
airflow sensor
I
Amount ofintake air ECM
&
EVAP
(ECCS canister
I
~Engine
coolanttemperature control
purgecon-
Engine coolant temperature sensor
module)trolsole-
I
noid
valve
Ignition switch
I
Start signal
I
This system cutsandcontrols vacuumappliedto
EGR valve andEVAP canister tosuit engine oper-
ating conditions. Thiscut-and-control operation
is accomplished throughtheECM andtheEGR
valve
&
EVAP canister purgecontrol solenoid
valve. WhentheECM detects anyofthe following
conditions, currentflowsthrough thesolenoid
valve. Thiscauses theport vacuum tobe dis-
charged intotheatmosphere. TheEGR valve and
EVAP canister remainclosed.
•
•
•
•
•
•
Low
engine coolant temperature
Engine starting
High-speed engineoperation
Engine idling
Excessively highengine coolant temperature
Mass airflow sensor malfunction
•
Exhaust pressure COMPONENT
DESCRIPTION
EGR valve
The EGR valve controls theamount ofexhaust gasrouted tothe
intake manifold. Vacuumisapplied tothe EGR valve in
response tothrottle valveopening. Thevacuum controls the
movement ofataper valve connected tothe vacuum diaphragm
in the EGR valve.
SEF783K EGRC-BPT valve
The EGRC-BPT valvemonitors exhaustpressure toactivate the
diaphragm, controllingthrottlebodyvacuum appliedtothe EGR
valve. Inother words, recirculated exhaustgasiscontrolled in
response topositioning ofthe EGR valve ortoengine operation.
SEF529K
~ Vacuumsignal
SEF240PE EGR
valve
&
EVAP canister purgecontrol solenoid valve
The EGR valve
&
EVAP canister purgecontrol solenoid valve
responds tosignals fromtheECM. When theECM sends anON
(ground) signal,thecoil inthe solenoid valveisenergized. A
plunger willthen move tocut the vacuum signal(fromthethrot-
tle body tothe EGR valve andEVAP canister purgevalve).
When theECM sends anOFF signal, thevacuum signalpasses
through thesolenoid valve.Thesignal thenreaches theEGR
valve andEVAP canister.
EC-319

TROUBLEDIAGNOSIS FORNON-DETECTABLE ITEMS
SYSTEM DESCRIPTION Idle
AirControl Valve(IACV) -Auxiliary Air
Control (AAC)Valve
Camshaft positionsensor Engine
speed
~
I
Amount ofintake air
Mass airflow sensor
I
Engine coolant temperature sensor Engine
coolant temperature
I
Ignition switch Start
signal
I
Throttle position sensor Throttle
"position
I
ECM
Inhibitor switch(A/Tmodels)/ Park/Neutral
position (ECCS
control
!
IACV-AAC valve
I
Neutral position switch(M/Tmodels)
module)
Air conditioner switch Air
conditioner operation
Power steering oilpressure switch Power
steering loadsignal
I
Battery Battery
voltage
Vehicle speedsensor Vehicle
speed
I
l
Cooling fan Cooling
fanoperation
I
This system automatically controlsengineidlespeed toaspecified level.Idlespeed iscontrolled
through fineadjustment ofthe amount ofair which bypasses thethrottle valveviaIACV-AAC valve.The
IACV-AAC valverepeats ON/OFF operation according tothe signal sentfrom theECM. Thecamshaft
position sensordetects theactual engine speedandsends asignal tothe ECM. TheECM thencontrols
the ON/OFF timeofthe IACV-AAC valvesothat engine speedcoincides withthetarget valuememo-
rized inECM. Thetarget engine speedisthe lowest speedatwhich theengine canoperate steadily.
The optimum valuestored inthe ECM isdetermined bytaking intoconsideration variousengine
conditions, suchasduring warmup,deceleration, andengine load(airconditioner, powersteering and
cooling fanoperation).
COMPONENTDESCRIPTION
IACV-AAC valve
The IACV-AAC valveismoved byON/OFF pulsesfromtheECM.
The longer theONpulse, thegreater theamount ofair that will
flow through thevalve. Themore airthat flows through the
valve, thehigher theidle speed.
Air SEF040E
EC-335
•