steering INFINITI QX56 2011 Factory Service Manual

STC-10
< WIRING DIAGRAM >
ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
WIRING DIAGRAM
ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
Wiring Diagram INFOID:0000000006256123
JCGWM0392GB
Revision: 2010 May2011 QX56

ELECTRONICALLY CONTROLLED POWER STEERING SYSTEMSTC-11
< WIRING DIAGRAM >
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STC
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JCGWM0393GB
Revision: 2010 May2011 QX56

STC-12
< WIRING DIAGRAM >
ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
JCGWM0394GB
Revision: 2010 May2011 QX56

DIAGNOSIS AND REPAIR WORK FLOWSTC-13
< BASIC INSPECTION >
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BASIC INSPECTION
DIAGNOSIS AND REPAIR WORK FLOW
Work FlowINFOID:0000000006256124
DETAILED FLOW
1.COLLECT THE INFORMATION FROM THE CUSTOMER
It is also important to clarify customer complaints before inspection. First of all, reproduce symptoms and
understand them fully. Ask customer about his/her complaints carefully. In some cases, it is necessary to
check symptoms by driving vehicle with customer.
CAUTION:
Customers are not professional. It is danger ous to make an easy guess like “maybe the customer
means that...,” or “maybe the cu stomer mentions this symptom”.
>> GO TO 2.
2.CHECK THE STATUS
1. Power steering fluid leakage and check the power steering fluid level. Refer to ST-30, "
Inspection".
2. Check the drive belt tension. Refer to EM-20, "
Checking".
3. Check the power steering gear for damages, cracks and fluid leakage. Refer to ST-46, "
Inspection".
4. Check the relief oil pressure. Refer to ST-52, "
Inspection".
>> GO TO 3.
3.DIAGNOSIS CHART BY SYMPTOM
Perform the diagnosis by symptom. Refer to STC-22, "
Diagnosis Procedure".
>> GO TO 4.
4.FINAL CHECK
Check the input/output standard values for the power steering control unit.
Are the power steering control unit input/output values within standard ranges respectively?
YES >> INSPECTION END
NO >> GO TO 2.
Revision: 2010 May2011 QX56

STC-14
< DTC/CIRCUIT DIAGNOSIS >
POWER SUPPLY AND GROUND CIRCUIT
DTC/CIRCUIT DIAGNOSIS
POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000006256125
1.CHECK POWER SUPPLY (1)
1. Turn the ignition switch OFF.
2. Disconnect power steering control unit harness connector.
3. Check the voltage between power steering control unit harness connector and ground.
4. Turn the ignition switch ON. CAUTION:
Never start the engine.
5. Check the voltage between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK POWER SUPPLY (2)
1. Turn the ignition switch OFF.
2. Check 10A fuse (#3).
3. Disconnect fuse block (J/B) harness connector.
4. Check the continuity between power steering cont rol unit harness connector and fuse block (J/B) harness
connector.
5. Check the continuity between power st eering control unit harness connector and ground.
Is the inspection result normal?
YES >> Perform trouble diagnosis for ignition power supply circuit. Refer to PG-89, "Wiring Diagram -
IGNITION POWER SUPPLY -".
NO >> Repair or replace damaged parts.
3.CHECK GROUND CIRCUIT
1. Turn the ignition switch OFF.
2. Check the continuity between power st eering control unit harness connector and ground.
Power steering control unit
—Voltage
Connector Terminal
M108 3 Ground 0 V
Power steering control unit — Voltage
Connector Terminal
M108 3 Ground Battery voltage
Power steering control unit Fuse block (J/B) Continuity
Connector Terminal Connector Terminal
M108 3 M1 2A Existed
Power steering control unit —Continuity
Connector Terminal
M108 3 Ground Not existed
Revision: 2010 May2011 QX56

POWER SUPPLY AND GROUND CIRCUITSTC-15
< DTC/CIRCUIT DIAGNOSIS >
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Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair or replace error-detected parts.
4.CHECK TERMINALS AND HARNESS CONNECTORS
Check the power steering control unit pin terminal s for damage or loose connection with harness connector.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Repair or replace error-detected parts.
Power steering control unit
—Continuity
Connector Terminal
M108 6 Ground Existed
Revision: 2010 May2011 QX56

STC-16
< DTC/CIRCUIT DIAGNOSIS >
POWER STEERING SOLENOID VALVE
POWER STEERING SOLENOID VALVE
Component Function CheckINFOID:0000000006256126
1.CHECK POWER STEERING SOLENOID VALVE OPERATION
Check changes in steering force from a halt condition to high-speed driving.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Check the power steering solenoid valve. Refer to STC-16, "
Diagnosis Procedure".
Diagnosis Procedure INFOID:0000000006256127
1.CHECK POWER STEERING SOLENOID VALVE SIGNAL
1. Turn the ignition switch OFF.
2. Check the voltage between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN POWER STEERING SO LENOID VALVE AND POWER STEERING CON-
TROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector.
3. Disconnect power steering control unit harness connector.
4. Check the continuity between power steering solenoid valve harness connector and the power steering
control unit harness connector.
5. Check the continuity between power st eering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK POWER STEERING SOLENOID VALVE
Check the power steering solenoid valve. Refer to STC-17, "
Component Inspection".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace gear-sub assembly. Refer to ST-43, "
Disassembly and Assembly".
Power steering control unit
— Condition Voltage (Approx.)
Connector Terminal
M108 1 Ground Vehicle speed: 0 km/h (0 MPH)
(Engine is running)
4.4 – 6.6 V
Vehicle speed: 100 km/h (62 MPH) 2.4 – 3.6 V
Power steering solenoid valve Power steering control unit Continuity
Connector Terminal Connector Terminal
F45 1
M108 1 Existed
25Existed
Power steering control unit — Continuity
Connector Terminal
M108 1
Ground Not existed
5
Revision: 2010 May2011 QX56

POWER STEERING SOLENOID VALVESTC-17
< DTC/CIRCUIT DIAGNOSIS >
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4.CHECK TERMINALS AND HARNESS CONNECTORS
 Check the power steering control unit pin terminal s for damage or loose connection with harness connector.
 Check the power steering solenoid valve pin termi nals for damage or loose connection with harness connec-
tor.
Is the inspection result normal?
YES >> Replace power steering control unit. Refer to STC-23, "Removal and Installation".
NO >> Repair or replace error-detected parts.
Component Inspection INFOID:0000000006256128
1.CHECK POWER STEERING SOLENOID VALVE
1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector.
3. Check resistance between power steering solenoid valve connector terminals.
4. Check power steering solenoid valve by listening for its operation sound while applying battery voltage to
power steering solenoid valve connector terminals 1 (positive) and 2 (negative).
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace gear-sub assembly. Refer to ST-43, "
Disassembly and Assembly".
Power steering solenoid valve
Resistance (Approx.)
Te r m i n a l
1 2 4 – 6 Ω
Revision: 2010 May2011 QX56

STC-18
< DTC/CIRCUIT DIAGNOSIS >
ENGINE SPEED SIGNAL CIRCUIT
ENGINE SPEED SIGNAL CIRCUIT
Diagnosis ProcedureINFOID:0000000006256129
1.PERFORM ECM SELF-DIAGNOSIS
With CONSULT-III
Perform “ENGINE” self-diagnosis.
Is any DTC detected?
YES >> Check the DTC. Refer to EC-98, "DTC Index".
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN ECM AND POWER STEERING CONTROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect ECM harness connectors.
3. Disconnect power steering control unit harness connector.
4. Check the continuity between ECM harness connecto r and power steering control unit harness connector.
5. Check the continuity between power st eering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK ENGINE SPEED SIGNAL (ECM)
1. Connect ECM harness connectors.
2. Check the signal between ECM harness connector and ground with oscilloscope.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace ECM. Refer to EC-143, "
Description".
ECM Power steering control unit
Continuity
Connector Terminal Connector Terminal
E80 169 M108 10 Existed
Power steering control unit — Continuity
Connector Terminal
M108 10 Ground Not existed
ECM — Condition Voltage (Approx.)
Connector Terminal
E80 169 Ground Engine is running
 Warm-up condition
 Idle speed
Engine is running
 Warm-up condition
 Engine speed: Approx. 2,000 rpm
JPBIA3352ZZ
JPBIA3354ZZ
Revision: 2010 May2011 QX56

ENGINE SPEED SIGNAL CIRCUITSTC-19
< DTC/CIRCUIT DIAGNOSIS >
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4.CHECK ENGINE SPEED SIGNAL (P OWER STEERING CONTROL UNIT)
1. Turn the ignition switch OFF.
2. Connect power steering control unit harness connector.
3. Check the signal between power steering control unit harness connector and ground with oscilloscope.
Is the inspection result normal?
YES >> GO TO 5.
NO >> Replace power steering control unit. Refer to STC-23, "
Removal and Installation".
5.CHECK TERMINALS AND HARNESS CONNECTORS
 Check the power steering control unit pin terminal s for damage or loose connection with harness connector.
 Check the ECM pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Repair or replace error-detected parts.
Power steering control unit — Condition Voltage (Approx.)
Connector Terminal
M108 10 Ground Engine is running
 Warm-up condition
 Idle speed
Engine is running
 Warm-up condition
 Engine speed: Approx. 2,000 rpm
JPBIA3352ZZ
JPBIA3354ZZ
Revision: 2010 May2011 QX56