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DTC/CIRCUIT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:000000 INFINITI QX56 2011 Factory Service Manual
TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-161
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DTC/CIRCUIT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:000000](/manual-img/42/57033/w960_57033-2184.png)
TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-161
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DTC/CIRCUIT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:0000000006217760
The specification (SP) value indicates the tolerance of
the value that is displayed in “SPEC” in “DATA MONI-
TOR” mode of CONSULT-III during normal operation of the Engine Control System. When the value in “SPEC”
in “DATA MONITOR” mode is within the SP value, t he Engine Control System is confirmed OK. When the
value in “SPEC” in “DATA MONITOR” mode is NOT wit hin the SP value, the Engine Control System may have
one or more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not illuminate
the MIL.
The SP value will be displayed for the following items:
B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board correc- tion)
A/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
MAS A/F SE-B1/B2 (The signal voltage of the mass air flow sensor)
IDLE FUEL PRES MAX/MIN (the signal voltage of the fuel rail pressure sensor)
Component Function CheckINFOID:0000000006217761
1.PRECONDITIONING
Check that all of the following conditions are satisfied.
TESTING CONDITION
Vehicle driven distance: More than 5,000 km (3,107 miles)
Barometric pressure: 98.3 - 104.3 kPa (0.983 - 1.043 bar, 1.003 - 1.064 kg/cm
2, 14.25 - 15.12 psi)
Atmospheric temperature: 20 - 30 °C (68 - 86 °F)
Engine coolant temperature: 75 - 95 °C (167 - 203 °F)
Transmission: Warmed-up
- After the engine is warmed up to normal operating temperat ure, drive vehicle until “ATF TEMP 2” (A/T fluid
temperature sensor signal) indicates more than 60 °C (140 °F).
Electrical load: Not applied
- Rear window defogger switch, air conditioner switch and li ghting switch are OFF. Steering wheel is straight
ahead.
Engine speed: Idle
Gear position: Neutral ( or parking)
>> GO TO 2.
2.PERFORM SPEC IN DATA MONITOR MODE
WITH CONSULT-III
NOTE:
Perform “SPEC” in “DATA MONITOR” mode in maximum scale display.
1. Perform EC-139, "
Work Procedure".
2. Select “B/FUEL SCHDL”, “A/F ALPHA-B1”, “A/F ALPHA-B2”, “MAS A/F SE-B1” in “SPEC” of “DATA
MONITOR” mode with CONSULT-III.
3. Check that monitor items are within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Proceed to EC-162, "
Diagnosis Procedure".
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EC-162
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
Diagnosis Procedure
INFOID:0000000006217762
OVERALL SEQUENCE
JSBIA0519GB
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DETAILED PROCEDURE
1.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
WITH CONSULT-III
1. Start engine.
2. Check that the testing conditions are met. Refer to EC-161, "
Component Function Check".
3. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
JMBIA0056GB
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EC-164
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
NOTE:
Check “A/F ALPHA-B1” and “A/F ALPHA-B2” for approxim
ately 1 minute because they may fluctuate. It is
NG INFINITI QX56 2011 Factory Service Manual
EC-164
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
NOTE:
Check “A/F ALPHA-B1” and “A/F ALPHA-B2” for approxim
ately 1 minute because they may fluctuate. It is
NG](/manual-img/42/57033/w960_57033-2187.png)
EC-164
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NOTE:
Check “A/F ALPHA-B1” and “A/F ALPHA-B2” for approxim
ately 1 minute because they may fluctuate. It is
NG if the indication is out of the SP value even a little.
Is the measurement value within the SP value?
YES >> GO TO 14.
NO-1 >> Less than the SP value: GO TO 2.
NO-2 >> More than the SP value: GO TO 3.
2.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 4.
NO >> More than the SP value: GO TO 16.
3.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 6.
NO-1 >> More than the SP value: GO TO 6.
NO-2 >> Less than the SP value: GO TO 22.
4.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Stop the engine.
2. Disconnect PCV hose, and then plug it.
3. Start engine.
4. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “ SPEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> GO TO 5.
NO >> GO TO 6.
5.CHANGE ENGINE OIL
1. Stop the engine.
2. Change engine oil. NOTE:
This symptom may occur when a large amount of gasoline is mixed with engine oil because of driving
conditions (such as when engine oil temperature does not rise enough since a journey distance is too
short during winter). The symptom will not be detec ted after changing engine oil or changing driving con-
ditions.
>> INSPECTION END
6.PERFORM POWER BALANCE TEST
1. Perform “POWER BALANCE” in “ACTIVE TEST” mode.
2. Check that each cylinder produces a momentary engine speed drop.
Is the inspection result normal?
YES >> GO TO 9.
NO >> GO TO 7.
7.DETECT MALFUNCTIONING PART
Check the following below.
Ignition coil and its circuit (Refer to EC-506, "
Component Function Check".)
Fuel injector and its circuit (Refer to EC-498, "
Component Function Check".)
Intake air leakage
Low compression pressure (Refer to EM-16, "
Inspection".)
Is the inspection result normal?
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YES >> Replace fuel injector and then GO TO 8.
NO >> Repair or replace malfunctioning INFINITI QX56 2011 Factory Service Manual
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YES >> Replace fuel injector and then GO TO 8.
NO >> Repair or replace malfunctioning](/manual-img/42/57033/w960_57033-2188.png)
TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-165
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YES >> Replace fuel injector and then GO TO 8.
NO >> Repair or replace malfunctioning part and then GO TO 8.
8.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> GO TO 9.
9.CHECK A/F SENSOR 1 FUNCTION
Perform all DTC CONFIRMATION PROCEDURE related with A/F sensor 1.
For DTC P0130, P0150, refer to EC-228, "
DTC Logic".
For DTC P0131, P0151, refer to EC-232, "
DTC Logic".
For DTC P0132, P0152, refer to EC-235, "
DTC Logic".
For DTC P0133, P0153, refer to EC-238, "
DTC Logic".
For DTC P2A00, P2A03, refer to EC-487, "
DTC Logic".
Are any DTCs detected?
YES >> GO TO 10.
NO >> GO TO 12.
10.CHECK A/F SENSOR 1 CIRCUIT
Perform Diagnosis Procedure according to corresponding DTC.
>> GO TO 11.
11 .CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> GO TO 12.
12.DISCONNECT AND RECONNECT ECM HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect ECM harness connector. Check pin term inal and connector for damage, and then reconnect it.
>> GO TO 13.
13.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “S PEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Detect malfunctioning part according to EC-524, "
Symptom Table".
14.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check t hat the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO-1 >> More than the SP value: GO TO 15.
NO-2 >> Less than the SP value: GO TO 22.
15.DETECT MALFUNCTIONING PART
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EC-166
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1. Check for the cause of large engine friction. Refer to the following.
- Engine oil level is too high
- Engine oil v INFINITI QX56 2011 Factory Service Manual
EC-166
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1. Check for the cause of large engine friction. Refer to the following.
- Engine oil level is too high
- Engine oil v](/manual-img/42/57033/w960_57033-2189.png)
EC-166
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1. Check for the cause of large engine friction. Refer to the following.
- Engine oil level is too high
- Engine oil viscosity
- Belt tension of power steering, alternat
or, A/C compressor, etc. is excessive
- Noise from engine
- Noise from transmission, etc.
2. Check for the cause of insufficient combustion. Refer to the following.
- Valve clearance malfunction
- Intake valve timing control function malfunction
- Camshaft sprocket installation malfunction, etc.
>> Repair or replace malfunctioning part, and then GO TO 27.
16.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.
Crushed air ducts
Malfunctioning seal of air cleaner element
Uneven dirt of air cleaner element
Improper specification of intake air system
Is the inspection result normal?
YES >> GO TO 18.
NO >> Repair or replace malfunctioning part, and then GO TO 17.
17.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2” AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2” and “B/FUE L SCHDL” in “SPEC” of “DATA MONITOR” mode, and
check that each indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> “B/FUEL SCHDL” is more, “A/F ALPHA-B1” and “A /F ALPHA-B2” are less than the SP value: GO
TO 18.
18.DISCONNECT AND RECONNECT MASS AIR FLOW SENSOR HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect mass air flow sensor harness connector. Check pin terminal and connector for damage and then reconnect it again.
>> GO TO 19.
19.CHECK “A/F ALPHA-B1” AND “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1” and “A/F ALPHA-B2” in “ SPEC” of “DATA MONITOR” mode, and check that each
indication is within the SP value.
Is the measurement value within the SP value?
YES >> Detect malfunctioning part of mass air flow sensor circuit and repair it. Refer to EC-201, "Diagno-
sis Procedure". Then GO TO 26.
NO >> GO TO 20.
20.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 21.
NO >> More than the SP value: Replace malfuncti oning mass air flow sensor, and then GO TO 26.
21.REPLACE ECM
1. Replace ECM.
2. Perform EC-143, "
Work Procedure".
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>> GO TO 26.
22.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mas INFINITI QX56 2011 Factory Service Manual
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>> GO TO 26.
22.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mas](/manual-img/42/57033/w960_57033-2190.png)
TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-167
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>> GO TO 26.
22.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.
Crushed air ducts
Malfunctioning seal in air cleaner element
Uneven dirt in air cleaner element
Improper specification in intake air system
Is the inspection result normal?
YES >> GO TO 24.
NO >> Repair or replace malfunctioning part, and then GO TO 23.
23.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and check t hat the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Less than the SP value: GO TO 24.
24.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and check that the indication is within the SP
value.
Is the measurement value within the SP value?
YES >> GO TO 25.
NO >> Less than the SP value: Replace malfunctioning mass air flow sensor, and then GO TO 27.
25.CHECK INTAKE SYSTEM
Check for the cause of air leakage after the mass air flow sensor. Refer to the following.
Disconnection, looseness, and cracks in air duct
Looseness of oil filler cap
Disconnection of oil level gauge
Open stuck, breakage, hose disconnection, or cracks in PCV valve
Disconnection or cracks in EVAP purge hose, stuc k open EVAP canister purge volume control solenoid
valve
Malfunctioning seal in rocker cover gasket
Disconnection, looseness, or cracks in hoses, such as a vacuum hose, connecting to intake air system parts
Malfunctioning seal in intake air system, etc.
>> GO TO 27.
26.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2” AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2” and “B/FUE L SCHDL” in “SPEC” of “DATA MONITOR” mode, and
check that each indication is within the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Detect malfunctioning part according to EC-524, "
Symptom Table".
27.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and then check that the indication is within
the SP value.
Is the measurement value within the SP value?
YES >> INSPECTION END
NO >> Detect malfunctioning part according to EC-524, "
Symptom Table".
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POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000006217763
1.CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
1. Di INFINITI QX56 2011 Factory Service Manual
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POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000006217763
1.CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
1. Di](/manual-img/42/57033/w960_57033-2191.png)
EC-168
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POWER SUPPLY AND GROUND CIRCUIT
POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000006217763
1.CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check the continuity between ECM harness connector and ground.
3. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.DETECT MALFUNCTIONING PART
Check the following.
Loose or poor connection for each connector and harness
Harness for open or short between ECM and ground
>> Repair open circuit or short to power in harness or connectors.
3.CHECK ECM POWER SUPPLY CIRCUIT-I
1. Reconnect ECM harness connector.
2. Turn ignition switch ON.
3. Check the voltage between ECM harness connector terminals.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
10 A fuse (No. 62)
Loose or poor connection for each connector and harness
Harness for open or short between ECM and fuse
>> Repair open circuit, short to ground or short to power in harness or connectors.
5.CHECK ECM POWER SUPPLY CIRCUIT-II
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Check the voltage between ECM harness connector terminals as per the following.
ECM Ground Continuity
Connector Terminal
F 111 1 0 Ground Existed
E80 174
175
ECM
Vo l ta g e
Connector +–
Terminal Terminal
E80 141 175 Battery voltage
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