Nissan Teana J32. Manual - part 1108

STC-1

STEERING

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SECTION 

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CONTENTS

STEERING CONTROL SYSTEM

BASIC INSPECTION  ....................................

2

DIAGNOSIS AND REPAIR WORK FLOW  .........

2

Work Flow  .................................................................

2

FUNCTION DIAGNOSIS ...............................

3

EPS SYSTEM  ......................................................

3

System Diagram ........................................................

3

System Description  ...................................................

3

Component Parts Location ........................................

5

Component Description .............................................

5

COMPONENT DIAGNOSIS  ..........................

6

POWER SUPPLY AND GROUND CIRCUIT .......

6

Description ................................................................

6

Diagnosis Procedure .................................................

6

POWER STEERING SOLENOID VALVE  ...........

7

Description ................................................................

7

Diagnosis Procedure .................................................

7

Component Inspection  ..............................................

8

ENGINE SPEED SIGNAL CIRCUIT  ....................

9

Description ................................................................

9

Diagnosis Procedure .................................................

9

VEHICLE SPEED SIGNAL CIRCUIT  .................

11

Description ..............................................................

11

Diagnosis Procedure ...............................................

11

ECU DIAGNOSIS .........................................

13

POWER STEERING CONTROL UNIT ..............

13

Reference Value ......................................................

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Wiring Diagram - ELECTRONICALLY CON-
TROLLED POWER STEERING SYSTEM -  ............

14

Fail-Safe ..................................................................

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SYMPTOM DIAGNOSIS  ..............................

17

UNBALANCE STEERING WHEEL TURNING 
FORCE (TORQUE VARIATION) .......................

17

Description ...............................................................

17

Diagnosis Procedure  ...............................................

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PRECAUTION ..............................................

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PRECAUTIONS .................................................

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Precaution for Supplemental Restraint System 
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" .................................................................

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Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect  ...................................

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ON-VEHICLE REPAIR .................................

19

POWER STEERING CONTROL UNIT ..............

19

Exploded View .........................................................

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Removal and Installation  .........................................

19

STC-2

< BASIC INSPECTION >

DIAGNOSIS AND REPAIR WORK FLOW

BASIC INSPECTION

DIAGNOSIS AND REPAIR WORK FLOW

Work Flow

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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 dangerous to make an easy guess like “maybe the customer
means that...,” or “maybe the customer mentions this symptom”.

>> GO TO 2.

2.

CHECK THE STATUS

1.

Check the power steering fluid leakage and power steering fluid level. Refer to 

ST-7, "Inspection"

.

2.

Check the drive belt tension. Refer to 

EM-12, "Checking"

.

3.

Check the power steering gear for damages, cracks and fluid leakage. Refer to 

ST-26, "Inspection"

.

4.

Check the relief oil pressure. Refer to 

ST-32, "Inspection"

.

>> GO TO 3.

3.

DIAGNOSIS CHART BY SYMPTOM

Perform the diagnosis by symptom. Refer to 

STC-17, "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.

EPS SYSTEM

STC-3

< FUNCTION DIAGNOSIS >

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FUNCTION DIAGNOSIS

EPS SYSTEM

System Diagram

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CONTROL DIAGRAM

CROSS-SECTIONAL VIEW

System Description

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• The EPS system controls the power steering solenoid valve through the power steering control unit.

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1.

Combination meter

2.

Power steering control unit

3.

Power steering solenoid valve

4.

Steering gear assembly

5.

Gear housing assembly

6.

Gear sub-assembly

7.

Pinion

8.

Power steering oil pump

9.

Reservoir tank

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STC-4

< FUNCTION DIAGNOSIS >

EPS SYSTEM

• The valve driving voltage to control the power steering solenoid

valve varies according to the vehicle speed.

OPERATION PRINCIPLE

During Parking (When Turning The Steering Wheel To The Right.)

1.

Power steering solenoid valve is closed while a vehicle is stopped.

2.

Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.

3.

Oil pressure “P” in the gear housing assembly is the sum of oil pressures occurred in “2R” and “3R”. This
results in a light steering force because of high pressure.

During High-speed Operation

1.

Power steering solenoid valve is opened during high-speed operation.

2.

Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.

3.

Oil pressure “2R” does not occur because the power steering solenoid valve is on full throttle.

4.

Oil pressure “P” in the gear housing assembly includes only oil pressure occurred in “3R” and results in a
heavy steering force.

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