2001 INFINITI QX4 Fuel

Wiring DiagramNBEC0640
MEC985C
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1464 FUEL LEVEL SENSOR CIRCUIT (GROUND SIGNAL)
Wiring Diagram
EC-583

Diagnostic Procedure=NBEC0641
1 CHECK FUEL LEVEL SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 59 and body ground. 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 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
1. Check the following.
IHarness connectors F27, M94
IHarness connectors M2, B1
IHarness for open between ECM and body ground
©Replace open circuit or short to power in harness or connectors.
3 CHECK FUEL LEVEL SENSOR
Refer to EL-108, ªFuel Level Sensor Unit Checkº.
OK or NG
OK©GO TO 4.
NG©Replace fuel level sensor unit.
4 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
OK or NG
©INSPECTION END
DTC P1464 FUEL LEVEL SENSOR CIRCUIT (GROUND SIGNAL)
Diagnostic Procedure
EC-584

SEF485T
Description=NBEC0346COMPONENT DESCRIPTIONNBEC0346S01The 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 DIAGRAMNBEC0346S02
SEF373Z
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0347Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
VC/V BYPASS/VIIgnition switch: ON OFF
ECM Terminals and Reference ValueNBEC0681Specification 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 P1490 VACUUM CUT VALVE BYPASS VALVE (CIRCUIT)
Description
EC-585

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

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

3 CHECK VACUUM CUT VALVE BYPASS VALVE OPERATION
Without CONSULT-II
1. Turn ignition switch ªOFFº.
2. Remove vacuum cut valve and vacuum cut valve bypass valve as an assembly.
3. Apply vacuum to port A and check that there is no suction from port B.
4. Apply vacuum to port B and check that there is suction from port A.
5. Blow air in port B and check that there is a resistance to flow out of port A.
6. Disconnect vacuum cut valve bypass valve harness connector.
7. Supply battery voltage to the terminal.
8. Blow air in port A and check that air flows freely out of port B.
9. Blow air in port B and check that air flows freely out of port A.
SEF914U
OK or NG
OK©GO TO 4.
NG©GO TO 7.
4 CHECK EVAP PURGE LINE
Check EVAP purge line between EVAP canister and fuel tank for clogging or disconnection.
OK or NG
OK©GO TO 5.
NG©Repair it.
5 CHECK EVAP PURGE PORT
Check EVAP purge port of fuel tank for clogging.
OK or NG
OK©GO TO 6.
NG©Clean EVAP purge port.
DTC P1491 VACUUM CUT VALVE BYPASS VALVE
Diagnostic Procedure (Cont'd)
EC-596

DTC Confirmation ProcedureNBEC0371CAUTION:
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.
SEF212Y
SEF213Y
WITH CONSULT-IINBEC0371S011) Turn ignition switch ªONº.
2) Select ªP/N POSI SWº in ªDATA MONITORº mode with CON-
SULT-II. Then check the ªP/N POSI SWº signal under the fol-
lowing conditions.
Position (Selector lever) Known-good signal
ªNº and ªPº position ON
Except the above position OFF
If NG, go to ªDiagnostic Procedureº, EC-608.
If OK, go to following step.
3) Select ªDATA MONITORº mode with CONSULT-II.
4) Start engine and warm it up to normal operating temperature.
5) Maintain the following conditions for at least 60 consecutive
seconds.
ENG SPEED 1,500 - 2,500 rpm
COOLAN TEMP/S More than 70ÉC (158ÉF)
B/FUEL SCHDL 3.6 - 12 msec
VHCL SPEED SE 70 - 100 km/h (43 - 62 MPH)
Selector lever Suitable position
6) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-608.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1706 PARK/NEUTRAL POSITION (PNP) SWITCH
DTC Confirmation Procedure
EC-605

SEF375Z
Component DescriptionNBEC0383The fuel injector is a small, precise solenoid valve. When the ECM
supplies a ground to the injector circuit, the coil in the injector is
energized. The energized coil pulls the needle valve back and
allows fuel to flow through the injector into the intake manifold. The
amount of fuel injected depends upon the injection pulse duration.
Pulse duration is the length of time the injector remains open. The
ECM controls the injection pulse duration based on engine fuel
needs.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0384Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
INJ PULSE-B2
INJ PULSE-B1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 2.4 - 3.2 msec
2,000 rpm 1.9 - 2.8 msec
B/FUEL SCHDL dittoIdle 2.0 - 3.2 msec
2,000 rpm 1.4 - 2.6 msec
ECM Terminals and Reference ValueNBEC0685Specification 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)
101
102
103
104
105
107R/B
L/W
R/W
PU/R
R/Y
R/LInjector No. 1
Injector No. 5
Injector No. 2
Injector No. 6
Injector No. 3
Injector No. 4[Engine is running]
IIdle speedBATTERY VOLTAGE
(11 - 14V)
INJECTOR
Component Description
EC-616