Page 1121 of 2395
On Board Diagnosis LogicNBEC0349Malfunction is detected when an improper voltage signal is sent to
ECM through vacuum cut valve bypass valve.
Possible CauseNBEC0592IHarness or connectors
(The vacuum cut valve bypass valve circuit is open or shorted.)
IVacuum cut valve bypass valve
DTC Confirmation ProcedureNBEC0350NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is more than 11V at idle speed.
SEF058Y
WITH CONSULT-IINBEC0350S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and wait at least 5 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-588.
WITH GSTNBEC0350S02Follow the procedure ªWITH CONSULT-IIº above.
DTC P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
On Board Diagnosis Logic
EC-586
Page 1122 of 2395
Wiring DiagramNBEC0351
MEC972C
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
Wiring Diagram
EC-587
Page 1123 of 2395
Diagnostic ProcedureNBEC0352
1 INSPECTION START
Do you have CONSULT-II?
YesorNo
Ye s©GO TO 2.
No©GO TO 3.
2 CHECK VACUUM CUT VALVE BYPASS VALVE CIRCUIT
With CONSULT-II
1. Turn ignition switch ªOFFº and then ªONº.
2. Select ªVC/V BYPASS/Vº in ªACTIVE TESTº mode with CONSULT-II.
3. Touch ªON/OFFº on CONSULT-II screen.
SEF014Z
4. Make sure that clicking sound is heard from the vacuum cut valve bypass valve.
OK or NG
OK©GO TO 7.
NG©GO TO 3.
DTC P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
Diagnostic Procedure
EC-588
Page 1124 of 2395

3 CHECK VACUUM CUT VALVE BYPASS VALUE POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect vacuum cut valve bypass valve harness connector.
SEF485T
3. Turn ignition switch ªONº.
4. Check voltage between vacuum cut valve bypass valve terminal 2 and ground with CONSULT-II or tester.
SEF015Z
OK or NG
OK©GO TO 5.
NG©GO TO 4.
4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors M2, B1
IFuse block (J/B) connector M10
IHarness connectors B43, B101 and B151, B152
I10A fuse
IHarness for open or short between vacuum cut valve bypass valve and fuse
©Repair harness or connectors.
5 CHECK VACUUM CUT VALVE BYPASS VALVE OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 39 and vacuum cut valve bypass valve terminal 1. Refer to Wiring
Diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 7.
NG©GO TO 6.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-589
Page 1125 of 2395
6 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors B152, B151 and B101, B43
IHarness connectors B1, M2 and M94, F27
IHarness for open or short between vacuum cut valve bypass valve and ECM
©Repair open circuit or short to ground or short to power in harness or connectors.
7 CHECK VACUUM CUT VALVE BYPASS VALVE
With CONSULT-II
1. Reconnect harness disconnected connectors.
2. Turn ignition switch ON.
3. Perform ªVC/V BYPASS/Vº in ªACTIVE TESTº mode.
4. Check air passage continuity and operation delay time under the following conditions.
SEF016Z
Without CONSULT-II
Check air passage continuity and operation delay time under the following conditions.
SEF358X
OK or NG
OK©GO TO 8.
NG©Replace vacuum cut valve bypass valve.
8 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
DTC P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-590
Page 1126 of 2395

SEF485T
DescriptionNBEC0353COMPONENT DESCRIPTIONNBEC0353S01The vacuum cut valve and vacuum cut valve bypass valve are
installed in parallel on the EVAP purge line between the fuel tank
and the EVAP canister.
The vacuum cut valve prevents the intake manifold vacuum from
being applied to the fuel tank.
The vacuum cut valve bypass valve is a solenoid type valve and
generally remains closed. It opens only for on board diagnosis.
The vacuum cut valve bypass valve responds to signals from the
ECM. When the ECM sends an ON (ground) signal, the valve is
opened. The vacuum cut valve is then bypassed to apply intake
manifold vacuum to the fuel tank.
EVAPORATIVE EMISSION SYSTEM DIAGRAMNBEC0353S02
SEF373Z
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0354Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
VC/V BYPASS/VIIgnition switch: ON OFF
ECM Terminals and Reference ValueNBEC0682Specification 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)
39 G/WVacuum cut valve
bypass valve[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
Description
EC-591
Page 1127 of 2395

On Board Diagnosis LogicNBEC0356Malfunction is detected when vacuum cut valve bypass valve does
not operate properly.
Possible CauseNBEC0593IVacuum cut valve bypass valve
IVacuum cut valve
IBypass hoses for clogging
IEVAP control system pressure sensor and circuit
IEVAP canister vent control valve
IHose between fuel tank and vacuum cut valve clogged
IHose between vacuum cut valve and EVAP canister clogged
IEVAP canister
IEVAP purge port of fuel tank for clogging
SEF210Y
SEF211Y
SEF239Y
DTC Confirmation ProcedureNBEC0357CAUTION:
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 10 seconds
before conducting the next test.
TESTING CONDITION:
For best results, perform test at a temperature of 5 to 30ÉC (41
to 86ÉF).
WITH CONSULT-IINBEC0357S011) Turn ignition switch ªONº.
2) Start engine and warm it up to normal operating temperature.
3) Turn ignition switch ªOFFº and wait at least 10 seconds.
4) Start engine and let it idle for at least 70 seconds.
5) Select ªVC CUT/V BP/V P1491º of ªEVAPORATIVE SYSTEMº
in ªDTC WORK SUPPORTº mode with CONSULT-II.
6) Touch ªSTARTº.
7) When the following conditions are met, ªTESTINGº will be dis-
played on the CONSULT-II screen. Maintain the conditions
continuously until ªTESTINGº changes to ªCOMPLETEDº. (It
will take at least 30 seconds.)
ENG SPEED Idle speed or more
Selector lever Suitable position
Vehicle speed 37 km/h (23 MPH) or more
B/FUEL SCHDL 1.3 - 10 msec
If ªTESTINGº is not displayed after 5 minutes, retry from
step 3.
8) Make sure that ªOKº is displayed after touching ªSELF-DIAG
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
On Board Diagnosis Logic
EC-592
Page 1128 of 2395
RESULTSº. If ªNGº is displayed, refer to ªDiagnostic
Procedureº, EC-595.
SEF530Q
Overall Function CheckNBEC0358Use this procedure to check the overall function of vacuum cut
valve bypass valve. During this check, the 1st trip DTC might not
be confirmed.
WITH GSTNBEC0358S011) Remove vacuum cut valve and vacuum cut valve bypass valve
as an assembly.
2) Apply vacuum to portAand check that there is no suction from
portB.
3) Apply vacuum to portBand check that there is suction from
portA.
4) Blow air in portBand check that there is a resistance to flow
out of portA.
5) Supply battery voltage to the terminal.
6) Blow air in portAand check that air flows freely out of portB.
7) Blow air in portBand check that air flows freely out of portA.
8) If NG, go to ªDiagnostic Procedureº, EC-595.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
DTC Confirmation Procedure (Cont'd)
EC-593