2011 INFINITI QX56 engine

EC-408
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1421 COLD START CONTROL
P1421 COLD START CONTROL
DescriptionINFOID:0000000006288263
ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way ca
talyst by heating the catalyst and reduces emissions.
DTC LogicINFOID:0000000006288264
DTC DETECTION LOGIC
NOTE:
If DTC P1421 is displayed with other DTC, firs t 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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Check the indication of “COOLAN TEMP/S”. If it is between 7 °C (45 °F) and 36 °C (97 °F), go to the following steps.
If it is below 7 °C (45 °F), warm engine up to more than 7 °C (45 °F) and retry from step 1.
If it is above 36 °C (97 °F), cool engine down to less than 36 °C (97 °F) and retry from step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-408, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288265
1.PERFORM IDLE AIR VOLUME LEARNING
Perform EC-148, "
Work Procedure".
Is Idle Air Volume Learning carried out successfully?
YES >> GO TO 2.
NO >> Follow the instruction of Idle Air Volume Learning.
2.CHECK INTAKE SYSTEM
Check for the cause of intake air volume lacking. Refer to the following.
 Crushed intake air passage
 Intake air passage clogging
Is the inspection result normal?
YES >> GO TO 3.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1421 Cold start emission reduction
strategy monitoring ECM does not control ignition timing and engine
idle speed properly when engine is started with
prewarming up condition.  Lack of intake air volume
 Fuel injection system
ECM
Revision: 2010 May2011 QX56

EC-410
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1423, P1424 COLD
START CONTROL
P1423, P1424 COLD START CONTROL
DescriptionINFOID:0000000006288266
ECM controls fuel injection timing and fuel injection quantity when engine is started with the engine cold.
This control promotes the activation of three way ca talyst by heating the catalyst and reduces emissions.
DTC LogicINFOID:0000000006288267
DTC DETECTION LOGIC
NOTE:
If DTC P1423 or P1424 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.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
WITH CONSULT-III
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Check that “COOLAN TEMP/S”.
- If it is between 5 °C (41 °F) and 40 °C (104 °F) go to the following steps.
- If it is below 5 °C (41 °F) warm engine up to more than 5 °C (41 °F) and retry from step 1.
- If it is above 40 °C (104 °F) cool engine down to less than 40 °C (104 °F) and retry from step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.
WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Proceed to EC-410, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288268
1.INSPECTION START
1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC confirmation procedure. Refer to EC-410, "
DTC Logic".
4. Check 1st trip DTC.
Is the 1st trip DTC P1423 or P1424 displayed again?
YES >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1423 COLD START CONTROL
(Cold start emission reduction
strategy monitoring) ECM does not control fuel injection timing prop-
erly when engine is started with the engine cold.
ECM
P1424 COLD START CONTROL
(Cold start emission reduction
strategy monitoring) ECM does not control fuel injection quantity
properly when engine is started with with the en-
gine cold.
Revision: 2010 May2011 QX56

EC-412
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1550 BATTERY CURRENT SENSOR
P1550 BATTERY CURRENT SENSOR
DTC LogicINFOID:0000000006217919
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, confi rm that battery voltage is 8 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-412, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217920
1.CHECK BATTERY CURRENT SENSO R POWER SUPPLY CIRCUIT-I
1. Disconnect battery current sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between battery current sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 8.
NO >> GO TO 2.
2.CHECK BATTERY CURRENT SENSO R POWER SUPPLY CIRCUIT-II
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1550 BAT CURRENT SENSOR
(Battery current sensor cir-
cuit range/performance) The output voltage of the battery
current sensor remains within
the specified range while engine
is running.  Harness or connectors
(Battery current sensor circuit is open or shorted.)
(Accelerator pedal position sensor 2 circuit is shorted.)
[Camshaft position sensor (bank 1) circuit is shorted.]
(Crankshaft position sensor circuit is shorted.)
(Refrigerant pressure sensor circuit is shorted.)
(EVAP control system pressure sensor circuit is short-
ed.)
 Battery current sensor
 Accelerator pedal position sensor
 Camshaft position sensor (bank 1)
 Crankshaft position sensor
 Refrigerant pressure sensor
 EVAP control system pressure sensor
Battery current sensor Ground Voltage (V)
Connector Terminal
E63 2 Ground Approx. 5
Revision: 2010 May2011 QX56

EC-420
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1553 BATTERY CURRENT SENSOR
P1553 BATTERY CURRENT SENSOR
DTC LogicINFOID:0000000006217925
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, confi rm that battery voltage is 8 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-420, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217926
1.CHECK BATTERY CURRENT SENSO R POWER SUPPLY CIRCUIT-I
1. Disconnect battery current sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between battery current sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 8.
NO >> GO TO 2.
2.CHECK BATTERY CURRENT SENSO R POWER SUPPLY CIRCUIT-II
DTC No.Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1553 BAT CURRENT SENSOR
(Battery current
sensor per-
formance) The signal voltage transmitted from
the sensor to ECM is higher than the
amount of the maximum power gener-
ation.  Harness or connectors
(Battery current sensor circuit is open or shorted.)
(Accelerator pedal position sensor 2 circuit is
shorted.)
[Camshaft position sensor (bank 1) circuit is
shorted.]
(Crankshaft position sensor circuit is shorted.)
(Refrigerant pressure sensor circuit is shorted.)
(EVAP control system pressure sensor circuit is
shorted.)
 Battery current sensor
 Accelerator pedal position sensor
 Camshaft position sensor (bank 1)
 Crankshaft position sensor
 Refrigerant pressure sensor
 EVAP control system pressure sensor
Battery current sensor Ground Voltage (V)
Connector Terminal
E63 2 Ground Approx. 5
Revision: 2010 May2011 QX56

EC-424
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1554 BATTERY CURRENT SENSOR
P1554 BATTERY CURRENT SENSOR
DTC LogicINFOID:0000000006217928
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PERFORM COMPONENT FUNCTION CHECK
Perform Component Function Check. Refer to EC-424, "
Component Function Check".
NOTE:
Use Component Function Check to check the overall functi on of the battery current sensor circuit. During this
check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Go to EC-425, "
Diagnosis Procedure".
Component Function CheckINFOID:0000000006217929
1.PRECONDITIONING
TESTING CONDITION:
 Before performing the following procedure, confirm that battery voltage is 12.8 V or more at idle.
 Before performing the following procedure, confi rm that all load switches and A/C switch are turned
OFF.
>> GO TO 2.
2.PERFORM COMPONENT FUNCTION CHECK
WITH CONSULT-III
1. Start engine and let it idle.
2. Select “BAT CUR SEN” in “DATA MONITOR” mode with CONSULT-III.
3. Check “BAT CUR SEN” indication for 10 seconds. “BAT CUR SEN” should be above 2,300 mV at least once.
WITHOUT CONSULT-III
1. Start engine and let it idle.
2. Check the voltage between ECM harness connector terminals as per the following.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1554 BAT CURRENT SENSOR
(Battery current
sensor per-
formance) The output voltage of the bat-
tery current sensor is lower than
the specified value while the
battery voltage is high enough.  Harness or connectors
(Battery current sensor circuit is open or shorted.)
(Accelerator pedal position sensor 2 circuit is shorted.)
[Camshaft position sensor (bank 1) circuit is shorted.]
(Crankshaft position sensor circuit is shorted.)
(Refrigerant pressure sensor circuit is shorted.)
(EVAP control system pressure sensor circuit is short-
ed.)
 Battery current sensor
 Accelerator pedal position sensor
 Camshaft position sensor (bank 1)
 Crankshaft position sensor
 Refrigerant pressure sensor
 EVAP control system pressure sensor
Revision: 2010 May2011 QX56

EC-428
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1556, P1557 BATTERY
TEMPERATURE SENSOR
P1556, P1557 BATTERY TEMPERATURE SENSOR
DTC LogicINFOID:0000000006217932
DTC DETECTION LOGIC
NOTE:
If DTC P1556 or P1557 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643.
Refer to EC-381, "
DTC 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, confi rm that battery voltage is 10 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start the engine and let it idle at least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-428, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217933
1.CHECK BATTERY TEMPERATURE SENSOR INPUT SIGNAL CIRCUIT-I
1. Disconnect battery current sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between battery current sensor hrness connector and ground.
Is the inspection result normal?
YES >> GO TO 7.
NO >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1556 BAT TMP SEN/CIRC
(Battery temperature sensor
circuit low input) Signal voltage from Battery
temperature sensor remains
0.16V or less for 5 seconds
or more. Harness or connectors
[Battery current sensor (Battery temperature sensor)
circuit is shorted.]
(Crankshaft position sensor circuit is open or shorted.)
[Camshaft position sensor (bank 1) circuit is shorted.]
(Accelerator pedal position sensor 2 circuit is shorted.)
(Refrigerant pressure sensor circuit is shorted.)
(EVAP control system pressure sensor circuit is short-
ed.)
 Battery current sensor (Battery temperature sensor)
 Crankshaft position sensor
 Camshaft position sensor (bank 1)
 Accelerator pedal position sensor 2
 Refrigerant pressure sensor
 EVAP control system pressure sensor
P1557
BAT TMP SEN/CIRC
(Battery temperature sensor
circuit high input) Signal voltage from Battery
temperature sensor remains
4.84V or more for 5 seconds
or more.
Battery current sensor
Ground Voltage (V)
Connector Terminal
E63 1 Ground Approx. 5
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]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
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