Infiniti QX4 (R50). Manual — part 281
SEF485T
Description
NBEC0353
COMPONENT DESCRIPTION
NBEC0353S01
The 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 DIAGRAM
NBEC0353S02
SEF373Z
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0354
Specification data are reference values.
MONITOR ITEM
CONDITION
SPECIFICATION
VC/V BYPASS/V
I
Ignition switch: ON
OFF
ECM Terminals and Reference Value
NBEC0682
Specification 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
COLOR
ITEM
CONDITION
DATA (DC Voltage)
39
G/W
Vacuum cut valve
bypass valve
[Ignition switch “ON”]
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
On Board Diagnosis Logic
NBEC0356
Malfunction is detected when vacuum cut valve bypass valve does
not operate properly.
Possible Cause
NBEC0593
I
Vacuum cut valve bypass valve
I
Vacuum cut valve
I
Bypass hoses for clogging
I
EVAP control system pressure sensor and circuit
I
EVAP canister vent control valve
I
Hose between fuel tank and vacuum cut valve clogged
I
Hose between vacuum cut valve and EVAP canister clogged
I
EVAP canister
I
EVAP purge port of fuel tank for clogging
SEF210Y
SEF211Y
SEF239Y
DTC Confirmation Procedure
NBEC0357
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously conducted,
always turn ignition switch “OFF” and wait at least 10 seconds
before conducting the next test.
TESTING CONDITION:
For best results, perform test at a temperature of 5 to 30°C (41
to 86°F).
WITH CONSULT-II
NBEC0357S01
1)
Turn ignition switch “ON”.
2)
Start engine and warm it up to normal operating temperature.
3)
Turn ignition switch “OFF” and wait at least 10 seconds.
4)
Start engine and let it idle for at least 70 seconds.
5)
Select “VC CUT/V BP/V P1491” of “EVAPORATIVE SYSTEM”
in “DTC WORK SUPPORT” mode with CONSULT-II.
6)
Touch “START”.
7)
When the following conditions are met, “TESTING” will be dis-
played on the CONSULT-II screen. Maintain the conditions
continuously until “TESTING” changes to “COMPLETED”. (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 “TESTING” is not displayed after 5 minutes, retry from
step 3.
8)
Make sure that “OK” is displayed after touching “SELF-DIAG
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
On Board Diagnosis Logic
EC-592
RESULTS”.
If
“NG”
is
displayed,
refer
to
“Diagnostic
Procedure”, EC-595.
SEF530Q
Overall Function Check
NBEC0358
Use 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 GST
NBEC0358S01
1)
Remove vacuum cut valve and vacuum cut valve bypass valve
as an assembly.
2)
Apply vacuum to port A and check that there is no suction from
port B.
3)
Apply vacuum to port B and check that there is suction from
port A.
4)
Blow air in port B and check that there is a resistance to flow
out of port A.
5)
Supply battery voltage to the terminal.
6)
Blow air in port A and check that air flows freely out of port B.
7)
Blow air in port B and check that air flows freely out of port A.
8)
If NG, go to “Diagnostic Procedure”, 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
Wiring Diagram
NBEC0359
MEC972C
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
Wiring Diagram
EC-594
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