2010 INFINITI QX56 steering

P0550 PSP SENSOREC-281
< COMPONENT DIAGNOSIS > [VK56DE]
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P0550 PSP SENSOR
Component DescriptionINFOID:0000000005149311
Power steering pressure (PSP) sensor (1) is installed to the power
steering high-pressure tube and detects a power steering load. This
sensor is a potentiometer which transforms the power steering load
into output voltage, and emits the voltage signal to the ECM. The
ECM controls the electric throttle control actuator and adjusts the
throttle valve opening angle to increase the engine speed and
adjusts the idle speed for the increased load.
On Board Diagnosis LogicINFOID:0000000005149312
The MIL will not light up for this self-diagnosis.
NOTE:
If DTC P0550 is displayed with DTC P0643, first pe
rform the trouble diagnosis for DTC P0643. Refer to
EC-289
.
DTC Confirmation ProcedureINFOID:0000000005149313
1. If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next step.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and let it idle for at least 5 seconds.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-281, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149314
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-85, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
BBIA0741E
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P0550
0550 Power steering pressure
sensor circuit An excessively low or high voltage from the
sensor is sent to ECM. • Harness or connectors
(The sensor circuit is open or shorted)
• Power steering pressure sensor
BBIA0354E
Revision: April 20092010 QX56

EC-282
< COMPONENT DIAGNOSIS >[VK56DE]
P0550 PSP SENSOR
2.CHECK PSP SENSOR POWER SUPPLY CIRCUIT
1. Disconnect power steering pressure (PSP) sensor (1) harness connector.
2. Turn ignition switch ON.
3. Check voltage between PSP sensor terminal 1 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connectors.
3.CHECK PSP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between PSP sensor terminal 3 and ECM terminal 67. Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK PSP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 12 and PSP sensor terminal 2.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK PSP SENSOR
Refer to EC-283, "
Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace PSP sensor.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
BBIA0741E
Voltage: Approximately 5V
PBIB0188E
Continuity should exist.
Continuity should exist.
Revision: April 20092010 QX56

P0550 PSP SENSOREC-283
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Component InspectionINFOID:0000000005149315
POWER STEERING PRESSURE SENSOR
1. Reconnect all harness connectors disconnected.
2. Start engine and let it idle.
3. Check voltage between ECM terminal 12 and ground under the
following conditions.
Condition Voltage
Steering wheel: Being turned. 0.5 - 4.5 V
Steering wheel: Not being turned. 0.4 - 0.8 V
MBIB0126E
Revision: April 20092010 QX56

P0643 SENSOR POWER SUPPLYEC-289
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P0643 SENSOR POWER SUPPLY
On Board Diagnosis LogicINFOID:0000000005149328
This self-diagnosis has the on
e trip detection logic.
FA I L - S A F E M O D E
When the malfunction is detected, ECM ent ers fail-safe mode and the MIL lights up.
DTC Confirmation ProcedureINFOID:0000000005149329
NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next step.
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 10 V at idle.
1. Start engine and let it idle for 1 second.
2. Check DTC.
3. If DTC is detected, go to EC-289, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149330
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-85, "
Ground Inspection".
OK or NG
OK >> GO TO 2.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0643
0643 Sensor power supply circuit
short ECM detects a voltage of power source
for sensor is excessively low or high. • Harness or connectors
(APP sensor 1 circuit is shorted.)
(PSP sensor circuit is shorted.)
(Battery current sensor circuit is shorted.)
(Refrigerant pressure se nsor circuit is short-
ed.)
(EVAP control system pressure sensor circuit
is shorted.)
• Accelerator pedal position sensor
• Power steering pressure sensor
• Refrigerant pressure sensor
• EVAP control system pressure sensor
Engine operation condition in fail-safe mode
ECM stops the electric throttle control actuator control, throttle valve is maintained at a fixed opening (approx. 5 degrees) b y the return
spring.
BBIA0354E
Revision: April 20092010 QX56

EC-290
< COMPONENT DIAGNOSIS >[VK56DE]
P0643 SENSOR POWER SUPPLY
NG >> Repair or replace ground connections.
2.CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect accelerator pedal position (APP) sensor harness connector.
2. Turn ignition switch ON.
3. Check voltage between APP sensor terminal 7 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 3.
3.CHECK SENSOR POWER SUPPLY CIRCUITS
Check harness for short to power and short to ground, between the following terminals
OK or NG
OK >> GO TO 4.
NG >> Repair short to ground or short to power in harness or connectors.
4.CHECK COMPONENTS
Check the following.
• EVAP control system pressure sensor (Refer to EC-248, "
Component Inspection".)
• Power steering pressure sensor (Refer to EC-283, "
Component Inspection".)
• Battery current sensor (Refer to EC-314, "
Component Inspection".)
• Refrigerant pressure sensor
OK or NG
OK >> GO TO 7.
NG >> Replace malfunctioning components.
5.CHECK ACCELERATOR PEDAL POSITION SENSOR
Refer to EC-381, "
Component Inspection".
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
BBIA0361E
Voltage: Approximately 5 V
JMBIA0601ZZ
ECM terminal Sensor terminal Reference Wiring Diagram
48 EVAP control system pressure sensor terminal 3
EC-435, "
Wiring Diagram - ENGINE
CONTROL SYSTEM -"
49Refrigerant pressure sensor terminal 1
Battery current sensor terminal 1
68 Power steering pressure sensor terminal 1
90 APP sensor terminal 7
Revision: April 20092010 QX56

EC-328
< COMPONENT DIAGNOSIS >[VK56DE]
P1564 ICC STEERING SWITCH
P1564 ICC STEERING SWITCH
Component DescriptionINFOID:0000000005149386
ICC steering switch has variant values of electrical
resistance for each button. ECM reads voltage variation of
switch, and determines which button is operated.
Refer to CCS-13, "
System Description" for the ICC function.
On Board Diagn osis LogicINFOID:0000000005149387
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this self-diagnosis .
NOTE:
If DTC P1564 is displayed with DTC P0605, first pe rform the trouble diagnosis for DTC P0605. Refer to
EC-286, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000005149388
1. If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next step.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Wait at least 10 seconds.
4. Press MAIN switch for at least 10 seconds, then release it and wait at least 10 seconds.
5. Press CANCEL switch for at least 10 seconds, then release it and wait at least 10 seconds.
6. Press RESUME/ACCELERATE switch for at least 10 seconds, then release it and wait at least 10 sec-
onds.
7. Press SET/COAST switch for at least 10 seconds , then release it and wait at least 10 seconds.
8. Press DISTANCE switch for at least 10 seconds, then release it and wait at least 10 seconds.
9. Check DTC.
10. If DTC is detected, go to EC-328, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149389
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
PBIB2640E
DTC No. Trouble diagnosis
name DTC detecting condition
Possible cause
P1564
1564 ICC steering switch • An excessively high voltage signal from the
ICC steering switch is sent to ECM.
• ECM detects that input signal from the ICC
steering switch is out of the specified range.
• ECM detects that the ICC steering switch is stuck ON. • Harness or connectors
(The switch circuit is open or shorted.)
• ICC steering switch
• Combination switch (spiral cable)
•ECM
Revision: April 20092010 QX56

P1564 ICC STEERING SWITCHEC-329
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Refer to
EC-85, "Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK ICC STEERING SWITCH CIRCUIT
With CONSULT-III
1. Turn ignition switch ON.
2. Select “MAIN SW”, “CANCEL SW ”, “RESUME/ACC SW”, “SET SW” and “DIST SW” in “DATA MONITOR”
mode with CONSULT-III.
3. Check each item indication under the following conditions.
Without CONSULT-III
1. Turn ignition switch ON.
2. Check voltage between ECM terminal 99 and ground with press- ing each button.
OK or NG
BBIA0354E
Switch Monitor item Condition Indication
MAIN switch MAIN SWPressed ON
Released OFF
CANCEL switch CANCEL SWPressed ON
Released OFF
RESUME/ACCELERATE
switch RESUME/ACC SWPressed ON
Released OFF
SET/COAST switch SET SW Pressed ON
Released OFF
DISTANCE switch DIST SW Pressed ON
Released OFF
Switch Condition Voltage [V]
MAIN switch Pressed
Approx. 0
Released Approx. 4.3
CANCEL switch Pressed
Approx. 1.3
Released Approx. 4.3
RESUME/ACCELERATE
switch Pressed
Approx. 3.7
Released Approx. 4.3
SET/COAST switch Pressed
Approx. 3.0
Released Approx. 4.3
DISTANCE switch Pressed
Approx. 2.2
Released Approx. 4.3
PBIB0311E
Revision: April 20092010 QX56

EC-330
< COMPONENT DIAGNOSIS >[VK56DE]
P1564 ICC STEERING SWITCH
OK >> GO TO 8.
NG >> GO TO 3.
3.CHECK ICC STEERING SWITCH GRO
UND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect combination switch harness connector M102.
4. Check harness continuity between combination switch terminal 15 and ECM terminal 67. Refer to Wiring Diagram.
5. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors M31, E152
• Harness connectors E5, F14
• Combination switch (spiral cable)
• Harness for open and short between ECM and combination switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK ICC STEERING SWITCH INPUT S IGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 99 and combination switch terminal 14. Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors M31, E152
• Combination switch (spiral cable)
• Harness for open and short between ECM and combination switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK ICC STEERING SWITCH
Refer to EC-330, "
Component Inspection".
OK or NG
OK >> GO TO 8.
NG >> Replace ICC steering switch.
8.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000005149390
ICC STEERING SWITCH
Continuity should exist.
Continuity should exist.
Revision: April 20092010 QX56