Infiniti QX56 (Z62). Manual - part 1267

STC-20

< DTC/CIRCUIT DIAGNOSIS >

VEHICLE SPEED SIGNAL CIRCUIT

VEHICLE SPEED SIGNAL CIRCUIT

Diagnosis Procedure

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1.

PERFORM COMBINATION METER SELF-DIAGNOSIS

With CONSULT-III

Perform “METER/M&A” self-diagnosis. Refer to 

MWI-30, "CONSULT-III Function"

.

Is any DTC detected?

YES

>> Check the DTC.

NO

>> GO TO 2.

2.

CHECK HARNESS BETWEEN COMBINATION METER AND POWER STEERING CONTROL UNIT

1.

Turn the ignition switch OFF.

2.

Disconnect combination meter harness connector.

3.

Disconnect power steering control unit harness connector.

4.

Check the continuity between combination meter harness connector and power steering control unit har-
ness connector.

5.

Check the continuity between power steering control unit harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace error-detected parts.

3.

CHECK VEHICLE SPEED SIGNAL (COMBINATION METER)

1.

Connect combination meter harness connector.

2.

Check the combination meter input/output standard values. Refer to 

MWI-35, "Reference Value"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Replace combination meter Refer to 

MWI-85, "Removal and Installation"

.

4.

CHECK VEHICLE SPEED SIGNAL (POWER 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.

Combination meter

Power steering control unit

Continuity

Connector

Terminal

Connector

Terminal

M34

30

M108

8

Existed

Power steering control unit

—

Continuity

Connector

Terminal

M108

8

Ground

Not existed

Power steering control unit

—

Condition

Voltage (Approx.)

Connector

Terminal

M108

 8

Ground

Vehicle speed: 40 km/h (25 MPH)

CAUTION:

Check air pressure of tire under 
standard condition.

NOTE:
The maximum voltage varies de-
pending on the specification (desti-
nation unit).

JSNIA0015GB

VEHICLE SPEED SIGNAL CIRCUIT

STC-21

< DTC/CIRCUIT DIAGNOSIS >

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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 terminals for damage or loose connection with harness connector.
• Check the combination meter 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.

STC-22

< SYMPTOM DIAGNOSIS >

UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIATION)

SYMPTOM DIAGNOSIS

UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIA-
TION)

Description 

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• Hard steering when fully turning the steering wheel.
• Light steering when driving at a high speed.

Diagnosis Procedure 

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1.

CHECK SYSTEM FOR POWER SUPPLY AND GROUND

Perform trouble diagnosis for power supply and ground. Refer to 

STC-14, "Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace error-detected parts.

2.

CHECK SYSTEM FOR VEHICLE SPEED SIGNAL

Perform trouble diagnosis for vehicle speed signal. Refer to 

STC-20, "Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace error-detected parts.

3.

CHECK SYSTEM FOR ENGINE SPEED SIGNAL

Perform trouble diagnosis for engine speed signal. Refer to 

STC-18, "Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair or replace error-detected parts.

4.

CHECK SYSTEM FOR POWER STEERING SOLENOID VALVE

Perform trouble diagnosis for power steering solenoid valve. Refer to 

STC-16, "Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> Perform the symptom diagnosis for the steering system. Refer to 

ST-29, "NVH Troubleshooting

Chart"

.

NO

>> Repair or replace error-detected parts.

POWER STEERING CONTROL UNIT

STC-23

< REMOVAL AND INSTALLATION >

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REMOVAL AND INSTALLATION

POWER STEERING CONTROL UNIT

Removal and Installation

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REMOVAL

1.

Remove instrument lower cover. Refer to 

IP-14, "Removal and Installation"

.

2.

Remove instrument lower panel RH. Refer to 

IP-14, "Removal and Installation"

.

3.

Disconnect power steering control unit connector.

4.

Remove power steering control unit.

INSTALLATION

Install in the reverse order of removal.