
SEF552W
COMPONENT DESCRIPTIONNLEC0227S02EGR Volume Control ValveNLEC0227S0201The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0502Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
EGR TEMP SEN+Engine: After warming up Less than 4.5V
EGR VOL CON/V+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: ªNº
+No-loadIdle 0 step
Revving engine up to 3,000 rpm
quickly10 - 55 step
ECM Terminals and Reference ValueNLEC0503Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
8
9
17
18SB
W/B
R/Y
BR/REGR volume control valve[Engine is running]
+Idle speed0 - 14V
58 B Sensor's ground[Engine is running]
+Warm-up condition
+Idle speed0V
72 P/B EGR temperature sensor[Engine is running]
+Warm-up condition
+Idle speedLess than 4.5V
[Engine is running]
+Warm-up condition
+EGR system is operating.0-1V
SEF073P
On Board Diagnosis LogicNLEC0228If the absence of EGR flow is detected by EGR temperature sen-
sor under the condition that calls for EGR, a low-flow malfunction
is diagnosed.
DTC P0400 EGR FUNCTION (CLOSED) (WHERE FITTED)QG18DE
Description (Cont'd)
EC-311

DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0400
0400+No EGR flow is detected under conditions that call for
EGR.+Harness or connectors
(EGR volume control valve circuit is open or
shorted.)
+EGR volume control valve stuck closed
+Dead (Weak) battery
+EGR passage clogged
+EGR temperature sensor and circuit
+Exhaust gas leaks
SEF013Y
SEF845Y
SEF846Y
SEF235Y
DTC Confirmation ProcedureNLEC0229CAUTION:
Always drive vehicle at a safe speed.
NOTE:
+If ªDTC Confirmation Procedureº has been previously
conducted, always turn ignition switch ªOFFº and wait at least
9 seconds before conducting the next test.
+P0400 will not be displayed at ªSELF-DIAG RESULTSº mode
with CONSULT-II even though DTC work support test result is
ªNGº.
TESTING CONDITION:
+Before performing the following procedure, confirm bat-
tery voltage is more than 10V at idle, then stop engine
immediately.
+For best result, perform the test at a temperature of 0ÉC
(32ÉF) or higher.
With CONSULT-II
1) Turn ignition switch ªOFFº and wait at least 9 seconds.
2) Turn ignition switch ªONº.
3) Check ªCOOLAN TEMP/Sº in ªDATA MONITORº mode with
CONSULT-II and confirm it is within the range listed below.
COOLAN TEMP/S: Less than 40ÉC (104ÉF)
If the value is out of range, park the vehicle in a cool place and
allow the engine temperature to stabilize. Do not attempt to
lower the engine coolant temperature with a fan or means
other than ambient air. Doing so may produce an inaccurate
diagnostic result.
4) Start engine and let it idle monitoring ªCOOLAN TEMP/Sº
value. When the ªCOOLAN TEMP/Sº value reaches 70ÉC
(158ÉF), immediately go to the next step.
5) Select ªEGR SYSTEM P0400º of ªEGR SYSTEMº in ªDTC
WORK SUPPORTº mode with CONSULT-II.
6) Touch ªSTARTº.
7) Accelerate vehicle to a speed of 40 km/h (25 MPH) once and
then stop vehicle with engine running.
If ªCOMPLETEDº appears on CONSULT-II screen, go to step
9.
If ªCOMPLETEDº does not appear on CONSULT-II screen, go
to the following step.
8) When the following conditions are met, ªTESTINGº will be dis-
played on the CONSULT-II screen. Maintain the conditions
until ªTESTINGº changes to ªCOMPLETEDº. (It will take
approximately 45 seconds or more.)
DTC P0400 EGR FUNCTION (CLOSED) (WHERE FITTED)QG18DE
On Board Diagnosis Logic (Cont'd)
EC-312

ENG SPEED Above 2,400 rpm
Vehicle speed Above 90 km/h (56 MPH)
B/FUEL SCHDL 4.0 - 8.0 msec
Selector lever 4th or 5th
If ªTESTINGº is not displayed after 5 minutes, retry from
step 2.
9) Make sure that ªOKº is displayed after touching ªSELF-DIAG
RESULTSº. If ªNGº is displayed, refer to ªDiagnostic
Procedureº, EC-316.
With GST
1) Turn ignition switch ªONº.
2) Check engine coolant temperature in MODE 1 with GST.
Engine coolant temperature: Less than 40ÉC (104ÉF)
If the value is out of range, park the vehicle in a cool place and
allow the engine temperature to stabilize. Do not attempt to
lower the engine coolant temperature with a fan or means
other than ambient air. Doing so may produce an inaccurate
diagnostic result.
3) Start engine and let it idle monitoring the value of ªCOOLAN
TEMP/Sº. When the engine coolant temperature reaches 70ÉC
(158ÉF), immediately go to the next step.
4) Maintain the following conditions for at least 1 minute.
Engine speed Above 2,400 rpm
Vehicle speed Above 90 km/h (56 MPH)
Selector lever 4th or 5th
5) Stop vehicle.
6) Turn ignition switch ªOFFº and wait at least 9 seconds, then
turn ªONº.
7) Repeat step 2 to 4.
8) Select ªMODE 3º with GST.
9) If DTC is detected, go to ªDIAGNOSTIC PROCEDUREº,
EC-316.
+When using GST, ªDTC CONFIRMATION PROCEDUREº
should be performed twice as much as when using CON-
SULT-II because GST cannot diaplay MODE 7 (1st trip
DTC) concerning this diagnosis. Therefore, using CON-
SULT-II is recommended.
DTC P0400 EGR FUNCTION (CLOSED) (WHERE FITTED)QG18DE
DTC Confirmation Procedure (Cont'd)
EC-313

DescriptionNLEC0504SYSTEM DESCRIPTIONNLEC0504S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
EGR vol-
ume controlEGR volume control valve Camshaft position sensor (PHASE) Engine speed and cylinder number
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Vehicle speed sensor Vehicle speed
Battery Battery voltage
Air conditioner switch Air conditioner operation
Power steering oil pressure switch Power steering load signal
Electrical load Electrical load signal
PNP switch Park/Neutral position signal
This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions. The EGR volume control
valve remains close under the following conditions.
+Low engine coolant temperature
+Engine starting
+High-speed engine operation
+Extremely light load engine operation
+Engine idling
+Excessively high engine coolant temperature
+Wide open throttle
+Mass air flow sensor malfunction
+Low battery voltage
SEF551W
DTC P0403 EGR VOLUME CONTROL VALVE (CIRCUIT)
(WHERE FITTED)
QG18DE
Description
EC-319

SEF184UD
On Board Diagnosis LogicNLEC0240The ECM monitors the switching frequency ratio of heated oxygen
sensors 1 (front) and 2 (rear).
A three way catalyst with high oxygen storage capacity will indicate
a low switching frequency of heated oxygen sensor 2 (rear). As
oxygen storage capacity decreases, the heated oxygen sensor 2
(rear) switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 (front) and
2 (rear) approaches a specified limit value, the three way catalyst
malfunction is diagnosed.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0420
0420+Three way catalyst does not operate properly.
+Three way catalyst does not have enough oxygen stor-
age capacity.+Three way catalyst
+Exhaust tube
+Intake air leaks
+Injectors
+Injector leaks
+Spark plug
+Improper ignition timing
SEF847Y
SEF848Y
SEF560X
DTC Confirmation ProcedureNLEC0241CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
TESTING CONDITION:
+Open engine hood before conducting following proce-
dure.
+Do not hold engine speed more than specified minutes
below.
1) Turn ignition switch ªONº.
2) Select ªDTC & SRT CONFIRMATIONº then ªSRT WORK SUP-
PORTº mode with CONSULT-II.
3) Start engine.
4) Rev engine up to 3,000±500 rpm and hold it for 3 consecutive
minutes then release the accelerator pedal completely.
If ªCOMPLETEDº appears on the CONSULT-II screen, go to
step 7.
5) Wait 5 seconds at idle.
6) Rev engine up to 2,500±500 rpm and maintain it until ªINCMPº
of CATALYST changes to ªCMPLTº (it will take approximately
5 minutes.)
If not ªCMPLTº, stop engine and cool it down to less than 70ÉC
(158ÉF) and then retest from step 1.
7) Select ªSELF-DIAG RESULTSº mode with CONSULT-II.
8) Confirm that the 1st trip DTC is not detected.
If the 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-328.
DTC P0420 THREE WAY CATALYST FUNCTIONQG18DE
On Board Diagnosis Logic
EC-327

DescriptionNLEC0248SYSTEM DESCRIPTIONNLEC0248S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
EVAP can-
ister purge
controlEVAP canister purge volume
control solenoid valve Camshaft position sensor (PHASE) Engine speed and cylinder number
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Battery Battery voltage
Ignition switch Start signal
Closed throttle position switch Closed throttle position
Throttle position sensor Throttle position
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Vehicle speed sensor Vehicle speed
This system controls flow rate of fuel vapor from the EVAP canis-
ter. The opening of the vapor by-pass passage in the EVAP canis-
ter purge volume control solenoid valve changes to control the flow
rate. The EVAP canister purge volume control solenoid valve
repeats ON/OFF operation according to the signal sent from the
ECM. The opening of the valve varies for optimum engine control.
The optimum value stored in the ECM is determined by consider-
ing various engine conditions. When the engine is operating, the
flow rate of fuel vapor from the EVAP canister is regulated as the
air flow changes.
SEF337U
COMPONENT DESCRIPTIONNLEC0248S02The EVAP canister purge volume control solenoid valve uses a
ON/OFF duty to control the flow rate of fuel vapor from the EVAP
canister. The EVAP canister purge volume control solenoid valve
is moved by ON/OFF pulses from the ECM. The longer the ON
pulse, the greater the amount of fuel vapor that will flow through the
valve.
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0249
MONITOR ITEM CONDITION SPECIFICATION
PURG VOL C/V+Engine: After warming up
+No-loadIdle 0%
Revving engine Ð
DTC P0443 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
(CIRCUIT)
QG18DE
Description
EC-332

4 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Refer to ªComponent Inspectionº EC-337.
OK or NG
OK©GO TO 5.
NG©Replace EVAP canister purge volume control solenoid valve.
5 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-145.
©INSPECTION END
SEF677Y
SEF661U
Component InspectionNLEC0255EVAP CANISTER PURGE VOLUME CONTROL
SOLENOID VALVE
NLEC0255S01With CONSULT-II
1) Start engine.
2) Perform ªPURG VOL CONT/Vº in ªACTIVE TESTº mode with
CONSULT-II. Check that engine speed varies according to the
valve opening.
If OK, inspection end. If NG, go to following step.
3) Check air passage continuity.
Condition
PURG VOL CONT/V valueAir passage continuity
between A and B
100.0% Yes
0.0% No
If NG, replace the EVAP canister purge volume control sole-
noid valve.
Without CONSULT-II
Check air passage continuity.
ConditionAir passage continuity
between A and B
12V direct current supply between ter-
minalsYe s
No supply No
If NG, replace the EVAP canister purge volume control solenoid
valve.
DTC P0443 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
(CIRCUIT)
QG18DE
Diagnostic Procedure (Cont'd)
EC-337

DescriptionNLEC0279SYSTEM DESCRIPTIONNLEC0279S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
Idle air con-
trolIACV-AAC valve Camshaft position sensor (PHASE) Engine speed and cylinder number
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
PNP switch Park/Neutral position
Air conditioner switch Air conditioner operation
Power steering oil pressure switch Power steering load signal
Battery Battery voltage
Vehicle speed sensor Vehicle speed
Cooling fan Cooling fan operation
Electrical load Electrical load signal
This system automatically controls engine idle speed to a specified
level. Idle speed is controlled through fine adjustment of the
amount of air which by-passes the throttle valve via IACV-AAC
valve. The IACV-AAC valve changes the opening of the air by-pass
passage to control the amount of auxiliary air. This valve is actu-
ated by a step motor built into the valve, which moves the valve in
the axial direction in steps corresponding to the ECM output sig-
nals. One step of IACV-AAC valve movement causes the respec-
tive opening of the air by-pass passage. (i.e. when the step
advances, the opening is enlarged.) The opening of the valve is
varied to allow for optimum control of the engine idling speed. The
crankshaft position sensor (POS) detects the actual engine speed
and sends a signal to the ECM. The ECM then controls the step
position of the IACV-AAC valve so that engine speed coincides with
the target value memorized in ECM. The target engine speed is the
lowest speed at which the engine can operate steadily. The opti-
mum value stored in the ECM is determined by taking into consid-
eration various engine conditions, such as during warm up,
deceleration, and engine load (air conditioner, power steering, cool-
ing fan operation and electrical load).
SEF937W
COMPONENT DESCRIPTIONNLEC0279S02IACV-AAC ValveNLEC0279S0202The IACV-AAC valve is operated by a step motor for centralized
control of auxiliary air supply. This motor has four winding phases
and is actuated by the output signals of ECM which turns ON and
OFF two windings each in sequence. Each time the IACV-AAC
valve opens or closes to change the auxiliary air quantity, the ECM
sends a pulse signal to the step motor. When no change in the
auxiliary air quantity is needed, the ECM does not issue the pulse
signal. A certain voltage signal is issued so that the valve remains
at that particular opening.
DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
QG18DE
Description
EC-343