ECU INFINITI QX56 2011 Factory Service Manual

EC-268
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
5.PERFORM DTC CONFIRMATION PROCEDURE-III
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine.
5. Maintain the following conditions for at least 10 consecutive minutes. Hold the accelerator pedal as steady as possible.
CAUTION:
Always drive vehicle at a safe speed.
6. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-268, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217828
1.CHECK EXHAUST GAS LEAKAGE
1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).
Is exhaust gas leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 2.
2.CHECK FOR INTAKE AIR LEAKAGE
Listen for an intake air leakage after the mass air flow sensor.
Is intake air leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 3.
3.CHECK A/F SENSOR 1 CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
Vehicle speed 50 - 120 km/h (31 - 75 MPH)
PBIB1216E
Revision: 2010 May2011 QX56

P0420, P0430 THREE WAY CATALYST FUNCTIONEC-307
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P0420, P0430 THREE WAY CATALYST FUNCTION
DTC LogicINFOID:0000000006217851
DTC DETECTION LOGIC
The ECM monitors the switching frequency ratio of air fuel ratio (A/F)
sensor 1 and heated oxygen sensor 2.
A three way catalyst (manifold) with high oxygen storage capacity
will indicate a low switching frequency of heated oxygen sensor 2.
As oxygen storage capacity decr
eases, the heated oxygen sensor 2
switching frequency will increase.
When the frequency ratio of A/F sensor 1 and heated oxygen sensor
2 approaches a specified limit value, the three way catalyst (mani-
fold) malfunction is diagnosed.
DTC CONFIRMATION PROCEDURE
1.INSPECTION START
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 6.
2.PERFORM DTC CONFIRMATION PROCEDURE-I
WITH CONSULT-III
TESTING CONDITION:
Do not maintain engine speed for mo re than the specified minutes below.
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 1 minute.
7. Select “DATA MONITOR” mode with CONSULT-III.
8. Check that “COOLAN TEMP/S” indicates more than 70 °C (158 °F).
If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches to 70°C (158 °F).
9. Open engine hood.
10. Select “DTC & SRT CONFIRMATION” then “SRT WORK SUPPORT” mode with CONSULT-III.
11. Rev engine between 2,000 and 3,000 rpm and hold it for 3 consecutive minutes then release the acceler-
ator pedal completely.
12. Check the indication of “CATALYST”.
Which is displayed on CONSULT-III screen?
CMPLT >> GO TO 5.
INCMP >> GO TO 3.
PBIB2055E
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0420 TW CATALYST SYS-B1
[Catalyst system efficiency
below threshold (bank 1)]
 Three way catalyst (manifold) does not
operate properly.
 Three way catalyst (manifold) does not have enough oxygen storage capacity.  Three way catalyst (manifold)
 Exhaust tube
 Intake air leakage
 Fuel injector
 Fuel injector leakage
 Spark plug
 Improper ignition timing
P0430
TW CATALYST SYS-B2
[Catalyst system efficiency
below threshold (bank 2)]
Revision: 2010 May2011 QX56

EC-352
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0460 FUEL LEVEL SENSOR
P0460 FUEL LEVEL SENSOR
DTC LogicINFOID:0000000006288328
DTC DETECTION LOGIC
NOTE:

If DTC P0460 is displayed with DTC UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
 If DTC P0460 is displayed with DTC P0607, first pe rform the trouble diagnosis for DTC P0607. Refer
to EC-378, "
DTC Logic".
When the vehicle is parked, the fuel level in the fuel tank is naturally stable. It means that output signal of the
fuel level sensor does not change. If ECM senses sloshi ng signal from the sensor, fuel level sensor malfunc-
tion is detected.
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and wait maximum of 2 consecutive minutes.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-352, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288329
1.CHECK DTC WITH “COMBINATION METER”
Refer to MWI-30, "
CONSULT-III Function".
Is any DTC detected?
YES >> Perform trouble diagnosis of detected DTC.
NO >> GO TO 2.
2.CHECK FUEL LEVEL SENSOR SIGNAL CIRCUIT
Check fuel level sensor signal circuit. Refer to MWI-69, "
Component Function Check".
Is the inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
NO >> Perform trouble diagnosis of fuel level sensor signal circuit. Refer to MWI-69,
"DiagnosisProcedure".
DTC No.Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0460 FUEL LEV SEN SLOSH
(Fuel level sensor circuit
noise) Even though the vehicle is parked, a
signal being varied is sent from the
fuel level sensor to ECM.  Harness or connectors
(The CAN communication line is open or shorted)
 Harness or connectors (The sensor circuit is open or shorted)
 Combination meter
 Fuel level sensor
Revision: 2010 May2011 QX56

EC-356
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0500 VSS
P0500 VSS
DescriptionINFOID:0000000006217857
The vehicle speed signal is sent to the “combination me
ter” from the “ABS actuator and electric unit (control
unit)” by CAN communication line. The “combination meter” then sends a signal to the ECM by CAN commu-
nication line.
DTC LogicINFOID:0000000006217858
DTC DETECTION LOGIC
NOTE:
 If DTC P0500 is displayed with DTC UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
 If DTC P0500 is displayed with DTC P0607, first pe rform the trouble diagnosis for DTC P0607. Refer
to EC-378, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.INSPECTION START
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 4.
2.CHECK VEHICLE SPEED SIGNAL
NOTE:
This procedure may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a
road test is expected to be easier, it is unnecessary to lift the vehicle.
WITH CONSULT-III
1. Start engine (VDC switch OFF).
2. Read “VHCL SPEED SE” in “DATA MONITOR” mode with CONSULT-III.
The vehicle speed on CONSULT-III should exceed 10 km/h (6 MPH) when rotating wheels with suitable
gear position.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Go to EC-357, "
Diagnosis Procedure".
3.PERFORM DTC CONFIRMATION PROCEDURE
1. Select “DATA MONITOR” mode with CONSULT-III.
2. Warm engine up to normal operating temperature.
3. Maintain the following conditions for at least 50 consecutive seconds. CAUTION:
Always drive vehicle at a safe speed.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0500 VEH SPEED SEN/CIRC
(Vehicle speed sensor) The vehicle speed signal sent to
E C M i s a l m o s t 0 k m / h ( 0 M P H ) e v e n
when vehicle is being driven.  Harness or connectors
(The CAN communication line is open or shorted)
 Harness or connectors (The vehicle speed signal circuit is open or shorted)
 Wheel sensor
 Combination meter
 ABS actuator and electric unit (control unit)
ENG SPEED More than 1,500 rpm
COOLAN TEMP/S More than 70 °C (158 °F)
Revision: 2010 May2011 QX56

EC-364
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0524 ENGINE OIL PRESSURE
P0524 ENGINE OIL PRESSURE
DTC LogicINFOID:0000000006288342
DTC DETECTION LOGIC
NOTE:
If DTC P0524 is displayed with DTC P0075 or P0081,
perform trouble diagnosis for DTC P0075 or P0081
first. Refer to EC-193, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING-I
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confi rm that battery voltage is between 10 V and 16 V at
idle.
>> GO TO 2.
2.PRECONDITIONING-II
Check oil level and oil pressure. Refer to LU-7, "
Inspection".
Is the inspection result normal?
YES >> GO TO 3.
NO >> Proceed to LU-7, "
Inspection".
3.PERFORM DTC CONFIRMATION PROCEDURE
WITH CONSULT-III
1. Select “DATA MONITOR” mode with CONSULT-III.
2. Maintain the following conditions for at least 20 consecutive seconds.
CAUTION:
Always drive at a safe speed.
3. Check 1st trip DTC.
WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Proceed to EC-365, "Diagnosis Procedure"
DTC No.Trouble diagnosis name
(Trouble diagnosis content) Detecting condition Possible cause
P0524 ENGINE OIL PRESSURE
(Engine oil pressure too low) Engine oil pressure is low because
there is a gap between angle of target
and phase-control angle.  Engine oil pressure or level too low
 Crankshaft position sensor
 Camshaft position sensor
 Intake valve timing control solenoid valve
 Accumulation of debris to the signal pick-up por-
tion of the camshaft
 Timing chain installation
 Foreign matter caught in the oil groove for intake valve timing control
ENG SPEED More than 1,700 rpm
COOLAN TEMP/S More than 70 °C (158 °F)
Selector lever 1st or 2nd position
Driving location uphill Driving vehicle uphill
(Increased engine load will help maintain the driving
conditions required for this test.)
Revision: 2010 May2011 QX56

P0850 PNP SWITCHEC-383
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P0850 PNP SWITCH
DescriptionINFOID:0000000006217884
When the selector lever position is P or N, park/neut
ral position (PNP) signal is sent to ECM from TCM.
DTC LogicINFOID:0000000006217885
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.INSPECTION START
Will CONSULT-III be used?
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 5.
2.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
>> GO TO 3.
3.CHECK PNP SIGNAL
WITH CONSULT-III
1. Turn ignition switch ON.
2. Select “P/N POSI SW” in “DATA MONITOR” mode wit h CONSULT-III. Then check the “P/N POSI SW” sig-
nal under the following conditions.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Go to EC-384, "
Diagnosis Procedure".
4.PERFORM DTC CONFIRMATION PROCEDURE
1. Select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to normal operating temperature.
3. Maintain the following conditions for at least 50 consecutive seconds. CAUTION:
Always drive vehicle at a safe speed.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0850 P-N POS SW/CIRCUIT
(Park/neutral position
switch) The signal of the park/neutral position (PNP)
signal does not change during driving after the
engine is started.  Harness or connectors
[The park/neutral position (PNP) signal
circuit is open or shorted.]
TCM
Position (Selector lever) Known-good signal
N or P position ON
Except above position OFF
ENG SPEED 1,300 - 6,375 rpm
COOLAN TEMP/S More than 70 °C (158 °F)
B/FUEL SCHDL 2.0 - 31.8 msec
Revision: 2010 May2011 QX56

EC-438
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1572 ASCD BRAKE SWITCH
P1572 ASCD BRAKE SWITCH
DTC LogicINFOID:0000000006217943
DTC DETECTION LOGIC
NOTE:

If DTC P1572 is displayed with DTC P0605, first pe rform the trouble diagnosis for DTC P0605. Refer
to EC-376, "
DTC Logic".
 This self-diagnosis has the one tr ip detection logic. When malfunction A is detected, DTC is not
stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed.
1st trip DTC is erased when ignition switch is tu rned OFF. And even when malfunction A is detected
in two consecutive trips, DTC is not stored in ECM memory.
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
NOTE:
The procedure for malfunction B is not described. It ta kes an extremely long time to complete the procedure
for malfunction B. By performing the procedure for malfunc tion A, the condition that causes malfunction B can
be detected.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A
1. Start engine (VDC switch OFF).
2. Press MAIN switch and check that CRUISE indicator is displayed in combination meter.
3. Drive the vehicle for at least 5 consec utive seconds under the following conditions.
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s lifted in the shop or by driving the vehicle.
If a road test is expected to be easier , it is unnecessary to lift the vehicle.
4. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-439, "Diagnosis Procedure".
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE
1. Drive the vehicle for at least 5 consec utive seconds under the following conditions.
CAUTION:
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1572 ASCD BRAKE SW
(ASCD brake switch) A)
When the vehicle speed is above 30 km/h
(19 MPH), ON signals from the stop lamp
switch and the ASCD brake switch are
sent to the ECM at the same time.  Harness or connectors
(The stop lamp switch circuit is shorted.)
 Harness or connectors
(The ASCD brake switch circuit is short-
ed.)
 Stop lamp switch
 ASCD brake switch
 Incorrect stop lamp switch installation
 Incorrect ASCD brake switch installation
ECM
B)
ASCD brake switch signal is not sent to
ECM for extremely long time while the ve-
hicle is being driven.
Vehicle speed More than 30 km/h (19 mph)
Selector lever Suitable position
Revision: 2010 May2011 QX56

P1572 ICC BRAKE SWITCHEC-443
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P1572 ICC BRAKE SWITCH
DTC LogicINFOID:0000000006217947
DTC DETECTION LOGIC
NOTE:

If DTC P1572 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-376, "
DTC Logic".
 This self-diagnosis has the one trip detection logic. When malfunction A is detected, DTC is not
stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed.
1st trip DTC is erased when ignition switch is tu rned OFF. And even when malfunction A is detected
in two consecutive trips, DTC is not stored in ECM memory.
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
NOTE:
The procedure for malfunction B is not described. It ta kes an extremely long time to complete the procedure
for malfunction B. By performing the procedure for malf unction A, the condition that causes malfunction B can
be detected.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine (VDC switch OFF).
2. Press MAIN switch and check that CRUISE i ndicator is displayed in combination meter.
3. Drive the vehicle for at least 5 consec utive seconds under the following conditions.
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s lifted in the shop or by driving the vehicle.
If a road test is expected to be easier , it is unnecessary to lift the vehicle.
4. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-444, "Diagnosis Procedure".
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE
1. Drive the vehicle for at least 5 consec utive seconds under the following conditions.
CAUTION:
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1572 ASCD BRAKE SW
(ICC brake switch) A)
ON signals from the stop lamp switch
and the ICC brake switch are sent to
ECM at the same time.  Harness or connectors
(The stop lamp switch circuit is shorted.)
 Harness or connectors
(The ICC brake switch circuit is shorted.)
Stop lamp switch
 ICC brake switch
 ICC brake hold relay
 Incorrect stop lamp switch installation
 Incorrect ICC brake switch installation
ECM
B)
ICC brake switch signal is not sent to
ECM for extremely long time while the
vehicle is being driven
Vehicle speed More than 30 km/h (19 mph)
Selector lever Suitable position
Revision: 2010 May2011 QX56

DRIVE BELTSEM-21
< PERIODIC MAINTENANCE >
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2. Install wrench (A) on drive belt auto tensioner pulley bolt, move
in the direction of arrow (loosening direction of tensioner) as
shown.
CAUTION:
 Never place hand in a location where pinching may occurif the holding tool accidentally comes off.
 Never loosen the hexagonal part in center of auto ten- sioner pulley (1) (Never turn it clockwise). If turned clock-
wise, the complete auto tensioner must be replaced as a
unit, including the pulley.
3. Under the above condition, insert a metallic bar (B) of approxi- mately 6 mm (0.24 in) in diameter (hexagonal bar wrench shown
as example in the figure) through the holding boss to lock auto tensioner pulley arm.
4. Remove drive belt.
INSTALLATION
Note the following item, and install in the reverse order of removal.
CAUTION:
 Check drive belts are securely installed around all pulleys.
 Check drive belts are correctly engaged with the pulley groove.
 Check for engine oil and engine coolant ar e not adhered drive belts and pulley groove.
InspectionINFOID:0000000006289528
INSPECTION AFTER INSTALLATION
 Turn crankshaft pulley clockwise several times to equalize tension between each pulley, and then confirm
tension of drive belts at indicator (notch on fixed side) is within the possible use range. Refer to EM-20,
"Exploded View".
JPBIA3484ZZ
Revision: 2010 May2011 QX56

EM-46
< REMOVAL AND INSTALLATION >
HIGH PRESSURE FUEL PUMP AND FUEL HOSE
 Check that rotation stopper (A) of fuel feed hose contact highpressure fuel pump.
6. Tighten mounting bolts that are temporarily tightened in step 3.
7. Connect harness connector to high pressure fuel pump.
8. Install fuel pump connector protector.
9. Connect harness connector to low fuel pressure sensor.
10. Note the following, and connect quick connector to install fuel feed hose.
a. Check the connection for foreign material and damage.
b. Align center to insert quick connector straightly into fuel tube. NOTE:
The figure shows engine side as an example.
 Insert fuel tube into quick connector until the top spool on fueltube is inserted completely and the second level spool is posi-
tioned slightly below quick connector bottom end.
CAUTION:
 Hold “A” position in the figure when inserting fuel tube
into quick connector.
 Carefully align center to avoid inclined insertion to pre-
vent damage to O-ring inside quick connector.
 Insert until you hear a “c lick” sound and actually feel
the engagement.
 To avoid misidentification of engagement with a similar sound , be sure to perform the next
step.
c. Before clamping fuel feed hose with hose clamps, pull quick connector hard by hand holding “A” position.
Check it is completely engaged (connected) so that it does not come out from fuel feed tube.
d. Install quick connector cap to quick connector connection.  Install so that the arrow mark on the side faces up.
CAUTION:
 Check that quick connector and fuel tube are securely fitinto quick connector cap installation groove.
 If quick connector cap canno t be installed smoothly,
quick connector may have not been installed correctly.
Check connection again.
11. Install in the reverse order of removal.
InspectionINFOID:0000000006289555
INSPECTION AFTER INSTALLATION
Check for Fuel Leakage
1. Turn ignition switch “ON” (with the engine stopped). With fuel pressure applied to fuel piping, check that
there is no fuel leakage at connection points.
NOTE:
Use mirrors for checking at points out of clear sight.
2. Start the engine. With engine speed increased, check again that there is no fuel leakage at connection
points.
JSBIA0364ZZ
KBIA0272E
PBIC2348E
Revision: 2010 May2011 QX56