engine INFINITI QX4 2001 Factory Service Manual

3 CHECK IACV-AAC VALVE OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals and IACV-AAC valve terminals as follows.
Refer to Wiring Diagram.
MTBL0354
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F101, F6
IHarness for open or short between IACV-AAC valve and ECM
©Repair harness connectors.
5 CHECK AIR CONTROL VALVE (POWER STEERING) OPERATION-I
1. Reconnect ECM harness connector and IACV-AAC valve harness connector.
2. Disconnect vacuum hose connected to air control valve (Power steering) at intake air duct.
3. Start engine and let it idle.
4. Check vacuum hose for vacuum existence.
SEF995Y
Vacuum slightly exists or does not exist.
OK or NG
OK©GO TO 6.
NG©Replace air control valve (Power steering).
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DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
Diagnostic Procedure (Cont'd)
EC-427

6 CHECK AIR CONTROL VALVE (POWER STEERING) OPERATION-II
Check vacuum hose for vacuum existence when steering wheel is turned.
SEF995Y
Vacuum should exist.
OK or NG
OK©GO TO 9.
NG©GO TO 7.
7 CHECK VACUUM PORT
1. Stop engine.
2. Disconnect vacuum hose connected to air control valve (Power steering) at vacuum port.
3. Blow air into vacuum port.
4. Check that air flows freely.
SEF996Y
OK or NG
OK©GO TO 8.
NG©Repair or clean vacuum port.
DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
Diagnostic Procedure (Cont'd)
EC-428

10 CHECK IACV-AAC VALVE-II
1. Reconnect IACV-AAC valve harness connector and ECM harness connector.
2. Turn ignition switch ªONº and ªOFFº, and ensure the IACV-AAC valve makes operating sound according to the ignition
switch position.
SEF997Y
OK or NG
OK©GO TO 12.
NG©GO TO 11.
11 REPLACE IACV-AAC VALVE
1. Replace IACV-AAC valve assembly.
2. Perform ªIdle Air Volume Learningº, EC-57.
Is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©INSPECTION END
INCMP©Follow the construction of ªIdle Air Volume Learningº.
12 CHECK TARGET IDLE SPEED
1. Turn ignition switch ªOFFº.
2. Reconnect all harness connectors and vacuum hoses.
3. Start engine and warm it up to normal operating temperature.
4. Also warm up transmission to normal operating temperature.
IFor A/T models with CONSULT-II, drive vehicle until ªFLUID TEMP SEº in ªDATA MONITORº mode of ªA/Tº system indi-
cates less than 0.9V.
IFor A/T models without CONSULT-II, drive vehicle for 10 minutes.
5. Stop vehicle with engine running.
6. Check target idle speed.
A/T: 750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 13.
NG©Perform ªIdle Air Volume Learningº, EC-57.
13 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
Diagnostic Procedure (Cont'd)
EC-430

SEF505V
Component DescriptionNBEC0256A closed throttle position switch and wide open throttle position
switch are built into the throttle position sensor unit. The wide open
throttle position switch is used only for A/T control.
When the throttle valve is in the closed position, the closed throttle
position switch sends a voltage signal to the ECM. The ECM only
uses this signal to open or close the EVAP canister purge volume
control solenoid valve when the throttle position sensor is malfunc-
tioning.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0257Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
CLSD THL/P SWIEngine: After warming up, idle
the engineThrottle valve: Idle position ON
Throttle valve: Slightly open OFF
ECM Terminals and Reference ValueNBEC0671Specification 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)
56 OR/LThrottle position switch
(Closed position)[Engine is running]
IAccelerator pedal fully releasedBATTERY VOLTAGE
(11 - 14V)
[Engine is running]
IAccelerator pedal depressedApproximately 0V
On Board Diagnosis LogicNBEC0259Malfunction is detected when battery voltage from the closed
throttle position switch is sent to ECM with the throttle valve
opened.
Possible CauseNBEC0516IHarness or connectors
(The closed throttle position switch circuit is shorted.)
IClosed throttle position switch
IThrottle position sensor
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DTC P0510 CLOSED THROTTLE POSITION SWITCH
Component Description
EC-431

SEF197Y
SEF198Y
DTC Confirmation ProcedureNBEC0260CAUTION:
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.
WITH CONSULT-IINBEC0260S011) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº, wait at least 10 seconds and then
start engine.
3) Select ªCLSD THL/P SWº in ªDATA MONITORº mode.
If ªCLSD THL/P SWº is not available, go to step 5.
4) Check the signal under the following conditions.
Condition Signal indication
Throttle valve: Idle position ON
Throttle valve: Slightly open OFF
If the result is NG, go to ªDiagnostic Procedureº, EC-435.
If OK, go to following step.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Drive the vehicle for at least 5 consecutive seconds under the
following condition.
THRTL POS SEN More than 2.5V
VHCL SPEED SE More than 5 km/h (3 MPH)
Selector lever Suitable position
Driving locationDriving vehicle uphill (Increased engine load)
will help maintain the driving conditions
required for this test.
7) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-435.
SEF345X
Overall Function CheckNBEC0261Use this procedure to check the overall function of the closed
throttle position switch circuit. During this check, a 1st trip DTC
might not be confirmed.
WITH GSTNBEC0261S011) Start engine and warm it up to normal operating temperature.
2) Check the voltage between ECM terminal 56 (Closed throttle
position switch signal) and ground under the following condi-
tions.
At idle: Battery voltage
DTC P0510 CLOSED THROTTLE POSITION SWITCH
DTC Confirmation Procedure
EC-432

Diagnostic ProcedureNBEC0263
1 CHECK CLOSED THROTTLE POSITION SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect throttle position switch harness connector.
SEF944Y
3. Turn ignition switch ªONº.
4. Check voltage between throttle position switch terminal 5 and engine ground with CONSULT-II or tester.
SEF346X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors M32, F23
IHarness for open or short between throttle position switch and ECM
©Repair harness or connectors.
3 CHECK CLOSED THROTTLE POSITION SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 56 and throttle position switch terminal 6.
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 P0510 CLOSED THROTTLE POSITION SWITCH
Diagnostic Procedure
EC-435

4 CHECK IGNITION TIMING AND ENGINE IDLE SPEED
Check the following items. Refer to ªBasic Inspectionº, EC-101.
MTBL0656
Models with CONSULT-II©GO TO 6.
Models without CON-
SULT-II©GO TO 6.
5 CHECK THROTTLE POSITION SWITCH
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Remove vacuum hose connected to throttle opener.
4. Connect suitable vacuum hose to vacuum pump and the throttle opener.
5. 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
6. Turn ignition switch ªONº.
7. Select ªDATA MONITORº mode with CONSULT-II.
8. 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 (With CONSULT-II)©GO TO 8.
OK (Without CONSULT-
II)©GO TO 9.
NG©GO TO 7.
DTC P0510 CLOSED THROTTLE POSITION SWITCH
Diagnostic Procedure (Cont'd)
EC-436

6 CHECK THROTTLE POSITION SWITCH
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Remove vacuum hose connected to throttle opener.
4. Connect suitable vacuum hose to vacuum pump and the throttle opener.
5. 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
6. Disconnect closed throttle position switch harness connector.
7. Check continuity between closed throttle position switch terminals 6 and 5 under the following conditions.
Resistance measurement must be made with throttle position switch installed in vehicle.
SEF998Y
OK or NG
OK (With CONSULT-II)©GO TO 8.
OK (Without CONSULT-
II)©GO TO 9.
NG©GO TO 7.
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DTC P0510 CLOSED THROTTLE POSITION SWITCH
Diagnostic Procedure (Cont'd)
EC-437

7 ADJUST THROTTLE POSITION SWITCH
Check the following items. Refer to ªBasic Inspectionº, EC-101.
MTBL0655
Is it possible to adjust closed throttle position switch?
YesorNo
Yes (With CONSULT-II)©GO TO 9.
Yes (Without CONSULT-
II)©GO TO 9.
No©Replace throttle position switch.
8 CHECK THROTTLE POSITION SENSOR
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine (ignition switch OFF).
3. Remove the vacuum hose connected to the throttle opener.
4. Connect suitable vacuum hose to the vacuum pump and the opener.
5. 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
6. Turn ignition switch ON.
7. Select ªDATA MONITORº mode with CONSULT-II.
8. Check voltage of ªTHRTL POS SENº under the following conditins.
Voltage measurement must be made with throttle position sensor installed in vehicle.
MTBL0230
OK or NG
OK©GO TO 10.
NG©Replace throttle position sensor.
DTC P0510 CLOSED THROTTLE POSITION SWITCH
Diagnostic Procedure (Cont'd)
EC-438

9 CHECK THROTTLE POSITION SENSOR
1. Start engine and warm it up to normal operating temperature.
2. Stop engine (ignition switch OFF).
3. Remove the vacuum hose connected to the throttle opener.
4. Connect suitable vacuum hose to the vacuum pump and the opener.
5. 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
6. Turn ignition switch ON.
7. Check voltage between ECM terminal 91 (Throttle position sensor signal) and ground.
Voltage measurement must be made with throttle position sensor installed in vehicle.
SEF348X
OK or NG
OK©GO TO 10.
NG©Replace throttle position sensor.
10 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0510 CLOSED THROTTLE POSITION SWITCH
Diagnostic Procedure (Cont'd)
EC-439