2001 INFINITI QX4 check engine

18 CHECK ABSOLUTE PRESSURE SENSOR
1. Remove absolute pressure sensor with its harness connector connected.
SEF961Y
2. Remove hose from absolute pressure sensor.
3. Install a vacuum pump to absolute pressure sensor.
4. Turn ignition switch ªONº and check output voltage between ECM terminal 80 and engine ground under the following
conditions.
SEF300XA
CAUTION:
IAlways calibrate the vacuum pump gauge when using it.
IDo not apply below þ93.3 kPa (±700 mmHg, ±27.56 inHg) or over 101.3 kPa (760 mmHg, 29.92 inHg) of pressure.
OK or NG
OK©GO TO 19.
NG©Replace absolute pressure sensor.
19 CHECK FUEL TANK TEMPERATURE SENSOR
1. Remove fuel level sensor unit.
2. Check resistance between fuel level sensor unit and fuel pump terminals 1 and 2 by heating with hot water or heat gun
as shown in the figure.
SEF974Y
OK or NG
OK©GO TO 20.
NG©Replace fuel level sensor unit.
DTC P1441 EVAP CONTROL SYSTEM (VERY SMALL LEAK)
Diagnostic Procedure (Cont'd)
EC-538

Diagnostic ProcedureNBEC0325
1 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect EVAP canister purge volume control solenoid valve harness connector.
SEF986Y
3. Turn ignition switch ªONº.
4. Check voltage between EVAP canister purge volume control solenoid valve terminal 1 and engine ground with CON-
SULT-II or tester.
SEF333X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors M32, F23
IFuse block (J/B) connector M10
I10A fuse
IHarness for open or short between EVAP canister purge volume control solenoid valve and fuse
©Repair harness or connectors.
3 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID 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 1 and EVAP canister purge volume control solenoid valve terminal 2.
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 4.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
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DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Diagnostic Procedure
EC-545

7 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
With CONSULT-II
1. Turn ignition switch ªOFFº.
2. Reconnect harness connectors disconnected.
3. Start engine.
4. Perform ªPURG VOL CONT/Vº in ªACTIVE TESTº mode with CONSULT-II. Check that engine speed varies according
to the valve opening.
SEF985Y
OK or NG
OK©GO TO 9.
NG©GO TO 8.
8 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
With CONSULT-II
Check air passage continuity of EVAP canister purge volume control solenoid valve under the following conditions.
SEF334X
Without CONSULT-II
Check air passage continuity of EVAP canister purge volume control solenoid valve under the following conditions.
SEF335X
OK or NG
OK©GO TO 9.
NG©Replace EVAP canister purge volume control solenoid valve.
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Diagnostic Procedure (Cont'd)
EC-548

SEF355X
Overall Function CheckNBEC0336Use this procedure to check the overall monitoring function of the
EVAP control system purge flow monitoring. During this check, a
1st trip DTC might not be confirmed.
WITH GSTNBEC0336S011) Lift up drive wheels.
2) Start engine (TCS switch ªOFFº) and warm it up to normal
operating temperature.
3) Turn ignition switch ªOFFº, wait at least 10 seconds.
4) Start engine and wait at least 70 seconds.
5) Set voltmeter probes to ECM terminals 84 (EVAP control sys-
tem pressure sensor signal) and ground.
6) Check EVAP control system pressure sensor value at idle
speed and note it.
7) Establish and maintain the following conditions for at least 1
minute.
Air conditioner switch ON
Steering wheel Fully turned
Headlamp switch ON
Rear window defogger switch ON
Engine speed Approx. 3,000 rpm
Gear position Any position other than ªPº, ªNº or ªRº
8) Verify that EVAP control system pressure sensor value stays
0.1V less than the value at idle speed (measured at step 6) for
at least 1 second.
9) If NG, go to ªDiagnostic Procedureº, EC-564.
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DTC P1447 EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM PURGE
FLOW MONITORING
Overall Function Check
EC-563

Diagnostic Procedure=NBEC0337
1 CHECK EVAP CANISTER
1. Turn ignition switch ªOFFº.
2. Check EVAP canister for cracks.
OK or NG
OK (With CONSULT-II)©GO TO 2.
OK (Without CONSULT-
II)©GO TO 3.
NG©Replace EVAP canister.
2 CHECK PURGE FLOW
With CONSULT-II
1. Disconnect vacuum hose connected to EVAP canister purge volume control solenoid valve at EVAP service port and
install vacuum gauge.
SEF983Y
2. Start engine and let it idle.
3. Select ªPURG VOL CONT/Vº in ªACTIVE TESTº mode with CONSULT-II.
4. Rev engine up to 2,000 rpm.
5. Touch ªQdº and ªQuº on CONSULT-II screen to adjust ªPURG VOL CONT/Vº opening and check vacuum existence.
SEF012Z
OK or NG
OK©GO TO 7.
NG©GO TO 4.
DTC P1447 EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM PURGE
FLOW MONITORING
Diagnostic Procedure
EC-564

3 CHECK PURGE FLOW
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine.
3. Disconnect vacuum hose connected to EVAP canister purge volume control solenoid valve at EVAP service port and
install vacuum gauge.
SEF983Y
4. Start engine and let it idle for at least 80 seconds.
5. Check vacuum gauge indication when revving engine up to 2,000 rpm.
Vacuum should exist.
6. Release the accelerator pedal fully and let idle.
Vacuum should not exist.
OK or NG
OK©GO TO 7.
NG©GO TO 4.
4 CHECK EVAP PURGE LINE
1. Turn ignition switch ªOFFº.
2. Check EVAP purge line for improper connection or disconnection.
Refer to ªEVAPORATIVE EMISSION LINE DRAWINGº, EC-36.
OK or NG
OK (With CONSULT-II)©GO TO 5.
OK (Without CONSULT-
II)©GO TO 6.
NG©Repair it.
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DTC P1447 EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM PURGE
FLOW MONITORING
Diagnostic Procedure (Cont'd)
EC-565

5 CHECK EVAP PURGE HOSE AND PURGE PORT
1. Disconnect purge hoses connected to EVAP service portAand EVAP canister purge volume control solenoid valveB.
SEF367U
2. Blow air into each hose and EVAP purge portC.
3. Check that air flows freely.
SEF368U
OK or NG
OK©GO TO 6.
NG©Repair or clean hoses and/or purge port.
6 CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
With 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.
SEF985Y
OK or NG
OK©GO TO 8.
NG©GO TO 7.
DTC P1447 EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM PURGE
FLOW MONITORING
Diagnostic Procedure (Cont'd)
EC-566

15 CHECK THROTTLE POSITION SWITCH
With CONSULT-II
1. Install all removed parts.
2. Start engine and warm it up to normal operating temperature.
3. Turn ignition switch ªOFFº.
4. Remove vacuum hose connected to throttle opener.
5. Connect suitable vacuum hose to vacuum pump and the throttle opener.
6. Apply vacuum [more than þ40.0 kPa (þ300 mmHg, þ11.81 inHg)] until the throttle drum becomes free from the rod of
the throttle opener.
SEF793W
7. Turn ignition switch ªONº.
8. Select ªDATA MONITORº mode with CONSULT-II.
9. Check indication of ªCLSD THL/P SWº under the following conditions.
Measurement must be made with throttle position switch installed in vehicle.
MTBL0355
OK or NG
OK©GO TO 18.
NG©GO TO 17.
DTC P1447 EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM PURGE
FLOW MONITORING
Diagnostic Procedure (Cont'd)
EC-570