2011 INFINITI QX56 air condition

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-161
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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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".
Revision: 2010 May2011 QX56

EC-164
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
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 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?
Revision: 2010 May2011 QX56

U1024 CAN COMM CIRCUITEC-175
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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U1024 CAN COMM CIRCUIT
DTC LogicINFOID:0000000006217770
DTC DETECTION LOGIC
NOTE:
If DTC U1024 is displayed with DTC P0607, fi
rst perform the trouble diagnosis for DTC P0607.
Refer to EC-378, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
TESTING CONDITION:
Before performing the following procedure, confi rm that battery voltage is 10 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON and wait at least 3 seconds.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-175, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217771
1.CHECK VVEL CAN COMMUNICATION CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect VVEL control module harness connector.
4. Check the continuity between ECM harness c onnector and VVEL control module harness connector.
5. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between ECM and VVEL control module
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connectors.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
U1024 VVEL CAN COMM CIRCUIT
(VVEL CAN communication)  When VVEL control module cannot transmitting
or receiving CAN communication signal with
ECM for 2 seconds or more.
 When detecting error during the initial diagnosis
of CAN controller of VVEL control module.  Harness or connectors
(CAN communication line is
open or shorted)
ECM
 VVEL control module
ECM VVEL control module Continuity
Connector Terminal Connector Terminal
E80 161
F56 24
Existed
166 11
Revision: 2010 May2011 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-181
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P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
DTC LogicINFOID:0000000006217775
DTC DETECTION LOGIC
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for at least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-181, "Diagnosis Procedure".
NG >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217776
1.CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect air fuel ratio (A /F) sensor 1 harness connector.
2. Turn ignition switch ON.
3. Check the voltage between A/F sensor 1 harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
DTC No. Trouble diagnosis
(Trouble diagnosis content) DTC detecting condition Possible cause
P0031 A/F SEN1 HTR (B1)
[A/F sensor 1 heater (bank
1) control circuit low] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
 A/F sensor 1 heater
P0032 A/F SEN1 HTR (B1)
[A/F sensor 1 heater (bank
1) control circuit high] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
 A/F sensor 1 heater
P0051 A/F SEN1 HTR (B2)
[A/F sensor 1 heater (bank
2) control circuit low] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
 A/F sensor 1 heater
P0052 A/F SEN1 HTR (B2)
[A/F sensor 1 heater (bank
2) control circuit high] The current amperage in the A/F sensor 1 heater
circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the A/F sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
 A/F sensor 1 heater
DTC A/F sensor 1
Ground Voltage
Bank Connector Terminal
P0031, P0032 1 F67 5 Ground Battery voltage
P0051, P0052 2 F68 5
Revision: 2010 May2011 QX56

P006A, P0101 MAF SENSOREC-187
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P006A, P0101 MAF SENSOR
DTC LogicINFOID:0000000006288269
DTC DETECTION LOGIC
NOTE:
If DTC P006A or P0101 is displayed with other DTC,
first perform the trouble diagnosis for other DTC.
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.
If engine will not start or stops soon, wait at leas t 10 seconds with engine stopped (Ignition switch ON) instead
of running engine at idle speed.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
WITH CONSULT-III
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to normal operating temperature.
3. Accelerate the vehicle from 0 km/h (0 MPH) to 88 km/h (55 MPH) under the following conditions:
CAUTION:
Always drive at a safe speed.
NOTE:
 Accelerate with the accelerator pedal kept constant.
 The acceleration at engine speed 2,000 and 3,000 rpm allows easy diagnoses
4. Check 1st trip DTC. WITHOUT CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. With selector lever in D position, accelerate the vehicle from 0 km/h (0 MPH) to 88 km/h (55 MPH) under
the following conditions:
NOTE:
 Accelerate with the accelerator pedal kept constant.
 The acceleration at engine speed 2,000 and 3,000 rpm allows easy diagnoses.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P006A MAP-MAF CORELTION-B1
(Manifold pressure
- mass air
flow correlation) A difference exceeding the specified value develops
between a value transmitted from the manifold absolute
pressure sensor to ECM and an estimated intake pres-
sure of intake manifold calculated by ECM, based on a
mass sir flow sensor signal.  Harness or connectors
(The sensor circuit is open
or shorted.)
 Mass air flow sensor
 Manifold absolute pressure
sensor
 EVAP control system pres-
sure sensor
 Intake air leaks
 Intake air temperature sen- sor
P0101 MAF SEN/CIRCUIT-B1
(Mass air flow sensor circuit
range/performance) A difference exceeding the specified value develops
between a signal transmitted from the mass air flow
sensor to ECM.
Mass air flow sensor
ACCEL SEN 1 1.4 – 2.0 V
Selector lever D position
Revision: 2010 May2011 QX56

EC-190
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P006A, P0101 MAF SENSOR
Component Inspection (MAF Sensor)
INFOID:0000000006288271
1.CHECK MASS AIR FLOW SENSOR-I
WITH CONSULT-III
1. Turn ignition switch OFF.
2. Reconnect all harness connectors disconnected.
3. Start engine and warm it up to normal operating temperature.
4. Connect CONSULT-III and select “DATA MONITOR” mode.
5. Select “MAS A/F SE-B1”, and check the indication.
*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
WITHOUT CONSULT-III
1. Turn ignition switch OFF.
2. Reconnect all harness connectors disconnected.
3. Start engine and warm it up to normal operating temperature.
4. Check the voltage between ECM harness connector terminals under the following conditions.
*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 2.
2.CHECK FOR THE CAUSE OF UNEVEN AIR FL OW THROUGH MASS AIR FLOW SENSOR
1. Turn ignition switch OFF.
2. 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 parts
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.CHECK MASS AIR FLOW SENSOR-II
WITH CONSULT-III
1. Repair or replace malfunctioning part.
2. Start engine and warm it up to normal operating temperature.
3. Connect CONSULT-III and select “DATA MONITOR” mode.
4. Select “MAS A/F SE-B1””, and check the indication.
Monitor item Condition Indication (V)
MAS A/F SE-B1 Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operating temperature.) 0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
ECM Condition Voltage (V)
Connector +–
Terminal Terminal
F 111 22
(MAF sensor signal) 25Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operat-
ing temperature.)
0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal
operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
Revision: 2010 May2011 QX56

P006A, P0101 MAF SENSOREC-191
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*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
WITHOUT CONSULT-III
1. Repair or replace malfunctioning part.
2. Start engine and warm it up to normal operating temperature.
3. Check the voltage between ECM harness connector terminals under the following conditions.
*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 4.
4.CHECK MASS AIR FLOW SENSOR-III
WITH CONSULT-III
1. Turn ignition switch OFF.
2. Disconnect mass air flow sensor har ness connector and reconnect it again.
3. Start engine and warm it up to normal operating temperature.
4. Connect CONSULT-III and select “DATA MONITOR” mode.
5. Select “MAS A/F SE-B1” , and check the indication.
*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
WITHOUT CONSULT-III
1. Turn ignition switch OFF.
2. Disconnect mass air flow sensor har ness connector and reconnect it again.
3. Start engine and warm it up to normal operating temperature.
4. Check the voltage between ECM harness connector terminals under the following conditions.
Monitor item Condition Indication (V)
MAS A/F SE-B1 Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operating temperature.) 0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
ECM
Condition Voltage (V)
Connector +–
Te r m i n a l Te r m i n a l
F 111 22
(MAF sensor signal) 25Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operat-
ing temperature.)
0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal
operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
Monitor item Condition Indication (V)
MAS A/F SE-B1 Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operating temperature.) 0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
Revision: 2010 May2011 QX56

EC-192
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P006A, P0101 MAF SENSOR
*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Clean or replace malfunctioning mass air flow sensor. Refer to
EM-27, "
Removal and Installation".
ECM
Condition Voltage (V)
Connector +–
Te r m i n a l Te r m i n a l
F 111 22
(MAF sensor signal) 25Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal operat-
ing temperature.)
0.9 - 1.1
2,500 rpm (Engine is warmed-up to normal
operating temperature.) 1.4 - 1.9
Idle to about 4,000 rpm 0.9 - 1.1 to Approx. 2.4*
Revision: 2010 May2011 QX56