2011 INFINITI QX56 ground

P0550 PSP SENSOREC-371
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P0550 PSP SENSOR
DTC LogicINFOID:0000000006217870
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.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for at least 5 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-371, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217871
1.CHECK POWER STEERING PRESSURE SENSOR POWER SUPPLY CIRCUIT-I
1. Turn ignition switch OFF.
2. Disconnect power steering pressure (PSP) sensor harness connector.
3. Turn ignition switch ON.
4. Check the voltage between PSP sensor harness connector terminals.
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 2.
2.CHECK POWER STEERING PRESSURE SENSOR POWER SUPPLY CIRCUIT-II
1. Check the voltage between PSP sensor harness connector and the ground.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0550 PW ST P SEN/CIRC
(Power steering pressure
sensor circuit) An excessively low or high voltage from the
sensor is sent to ECM.  Harness or connectors
(The Fuel rail pressure sensor circuit is
open or shorted.)
(The Power steering pressure sensor cir-
cuit is open or shorted)
(The Electrically-controlled cooling fan
coupling circuit is open or shorted)
 Fuel rail pressure sensor
 Power steering pressure sensor
 Electrically-controlled cooling fan cou- pling
PSP sensor Vo l ta g e
(Approx.)
Connector +
−
terminal
F35 1 3 5 V
Revision: 2010 May2011 QX56

EC-372
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0550 PSP SENSOR
Is inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.CHECK SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness connector for short to power and short to ground, between the following terminals.
Is inspection result normal?
YES >> Perform the trouble diagnosis for power supply circuit. Refer to EC-168, "Diagnosis Procedure".
NO >> Repair or replace error-detected parts.
4.CHECK PSP SENSOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between PSP sens or harness connector and ECM harness connector.
4. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace error-detected parts.
5.CHECK ECM GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between ECM harness connector and the ground.
Is inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
+
−Voltag e
(Approx.)
PSP sensor
Connector terminal F35 1 Ground 5 V
ECM Sensor
Connector Terminal Name Connector Terminal
F 111 27Low fuel pressure sensor F25 3
Power steering pressure sensor F35 1
Cooling fan speed sensor F39 2
28 FRP sensor F26 1
+ −
Continuity
PSP sensor ECM
Connector Terminal Connector Terminal F35 3 F111 45 Existed
+ −Continuity
ECM
Connector Terminal F 111 1 0 Ground Existed
E80 174
175
Revision: 2010 May2011 QX56

P0550 PSP SENSOREC-373
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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NO >> Repair or replace error-detected parts.
6.CHECK PSP SENSOR SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between PSP sens or harness connector and ECM harness connector.
4. Also check harness for short to ground and to power.
Is the inspection result normal?
YES >> GO TO 7.
NO >> Repair or replace error-detected parts.
7.CHECK PSP SENSOR
Refer to EC-373, "
Component Inspection (Power Steering Pressure Sensor)".
Is the inspection result normal?
YES >> GO TO 8.
NO >> Replace PSP sensor.
8.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (Power Steering Pressure Sensor)INFOID:0000000006217872
1.CHECK POWER STEERING PRESSURE SENSOR
1. Turn ignition switch OFF.
2. Reconnect all harness connectors disconnected.
3. Start engine and let it idle.
4. Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace power steering pressure sensor.
+ −
Continuity
PSP sensor ECM
Connector Terminal Connector Terminal F35 2 F111 39 Existed
ECM Condition Voltage (V)
Connector +–
Te r m i n a l Te r m i n a l
F111 39 45 Steering wheel Being turned 0.5 - 4.5
Not being turned 0.4 - 0.8
Revision: 2010 May2011 QX56

P0643 SENSOR POWER SUPPLYEC-381
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P0643 SENSOR POWER SUPPLY
DTC LogicINFOID:0000000006217882
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 1 second.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-381, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217883
1.CHECK ACCELERATOR PEDAL POSITION SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect accelerator pedal position (APP) sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between APP sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 2.
2.CHECK SENSOR POWER SUPPLY CIRCUIT
Check harness for short to power and short to ground, between the following terminals.
DTC No.Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0643 SENSOR POWER/CIRC
(Sensor power su
pply circuit
short) ECM detects that the voltage of
power source for sensor is ex-
cessively low or high.  Harness or connectors
(Accelerator pedal position sensor 1 circuit is shorted.)
[Camshaft position sensor (bank 2) circuit is shorted.]
[Manifold absolute pressure (MAP) sensor circuit is
shorted.]
(Throttle position sensor circuit is shorted.)
 Accelerator pedal position sensor 1
 Camshaft position sensor (bank 2)
 Manifold absolute pressure (MAP) sensor
 Throttle position sensor
APP sensor Ground Voltage (V)
Connector Terminal
E110 (Without ICC) 2 Ground Approx. 5
E67 (With ICC) 12
Revision: 2010 May2011 QX56

EC-382
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0643 SENSOR POWER SUPPLY
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair short to ground or short to power in harness or connectors.
3.CHECK COMPONENTS
Check the following.
 Camshaft position sensor (bank 2) (Refer to EC-306, "
Component Inspection (Camshaft Position Sensor)".)
 Manifold absolute pressure (MAP) sensor (Refer to EC-208, "
Component Inspection (MAP Sensor)".)
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace malfunctioning component.
4.CHECK THROTTLE POSITION SENSOR
Refer to EC-220, "
Component Inspection (Throttle Position Sensor)".
Is the inspection result normal?
YES >> GO TO 8.
NO >> GO TO 5.
5.REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR
Replace electric throttle control actuator. Refer to EM-30, "
Removal and Installation".
>> INSPECTION END
6.CHECK ACCELERATOR PEDAL POSITION SENSOR
Refer to EC-470, "
Component Inspection (Accelerator Pedal Position Sensor)".
Is the inspection result normal?
YES >> GO TO 8.
NO >> GO TO 7.
7.REPLACE ACCELERATOR PEDAL ASSEMBLY
Replace accelerator pedal assembly. Refer to ACC-3, "
MODELS WITHOUT DISTANCE CONTROL ASSIST
SYSTEM : Removal and Installation" (Without distance control assist system) or ACC-4, "MODELS WITH
DISTANCE CONTROL ASSIST SYSTEM : Removal and Installation" (With distance control assist system).
>> INSPECTION END
8.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
ECM Sensor
Connector Terminal Name Connector Terminal
F 111 81 Electric throttle control actuator F66 2
83 Camshaft position sensor (bank 2) F83 1
85 Manifold absolute pressure (MAP) sensor F65 1
E80 137 APP sensor 1 (Without ICC) E110 2
137 APP sensor 1 (With ICC) E67 12
Revision: 2010 May2011 QX56

P0850 PNP SWITCHEC-385
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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5. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between A/T assembly and ECM
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connectors.
5.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
A/T assembly ECM Continuity
Connector Terminal Connector Terminal
F 3 0 1 9 F 111 11 E x i s t e d
Revision: 2010 May2011 QX56

P1089, P1092 VVEL CONTROL SHAFT POSITION SENSOR
EC-387
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P1089, P1092 VVEL CONTROL
SHAFT POSITION SENSOR
DTC LogicINFOID:0000000006217894
DTC DETECTION LOGIC
NOTE:
If DTC P1089 or P1092 is displayed with DTC P1608, first perform the trouble diagnosis for DTC P1608.
Refer to EC-453, "
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 engine and let it idle for 1 second.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-387, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217895
1.VVEL CONTROL SHAFT POSITION SENSOR POWER SUPPLY CIRCUIT
1. Disconnect VVEL control shaft pos ition sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between VVEL control shaf t position sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.DETECT MALFUNCTIONING PART
Check the following.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1089 VVEL POS SEN/CIRC-B1
[VVEL control shaf
t position sen-
sor (bank 1) circuit]  An excessively low voltage from the sensor
is sent to VVEL control module.
 An excessively high voltage from the sensor is sent to VVEL control module.
 Rationally incorrect voltage is sent to VVEL control module compared with the signals
from VVEL control shaft position sensor 1
and VVEL control shaft position sensor 2.  Harness or connectors
(VVEL control shaft position sen-
sor circuit is open or shorted.)
 VVEL control shaft position sen- sor
 VVEL control module
P1092 VVEL POS SEN/CIRC-B2
[VVEL control shaf
t position sen-
sor (bank 2) circuit]
DTC No. VVEL control shaft position sensor
Ground Voltage (V)
Bank Connector Terminal
P1089 1 F72 3
Ground Approx. 5
6
P1092 2 F70 3
6
Revision: 2010 May2011 QX56

EC-388
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1089, P1092 VVEL CONTRO
L SHAFT POSITION SENSOR
 Harness for open or short between VVEL control shaft position sensor 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.
3.CHECK VVEL CONTROL SHAFT POSITION SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect VVEL control module harness connector.
3. Check the continuity between VVEL control shaf t position sensor harness connector and VVEL control
module harness connector.
4. Also check harness for short to ground and power.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between VVEL control shaft position sensor 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.
5.VVEL CONTROL SHAFT POSITI ON SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check the continuity between VVEL control shaf t position sensor harness connector and VVEL control
module harness connector.
2. Also check harness for short to ground and power.
Is the inspection result normal?
YES >> GO TO 7.
NO >> GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between VVEL control shaft position sensor 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.
7.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
DTC No. VVEL control shaft position
sensor VVEL control module
Continuity
Bank Connector Terminal Connector Terminal
P1089 1 F72 2
F56 6
Existed
519
P1092 2 F70 24
517
DTC No.VVEL control shaft position
sensor VVEL control module
Continuity
Bank Connector Terminal Connector Terminal
P1089 1 F72 1
F56 3
Existed
416
P1092 2 F70 15
418
Revision: 2010 May2011 QX56