Nissan Maxima. Manual - part 1124

STC-2

< BASIC INSPECTION >

DIAGNOSIS AND REPAIR WORKFLOW

BASIC INSPECTION

DIAGNOSIS AND REPAIR WORKFLOW

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 will be necessary to

check symptoms by driving vehicle with customer.

>> GO TO 2.

2.

BASIC INSPECTION

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

ST-12, "Inspection"

.

2. Check the drive belt tension. Refer to 

EM-14, "Checking Drive Belts"

.

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

ST-12, "Inspection"

.

4. Check the relief oil pressure. Refer to 

ST-16, "Inspection"

.

>> GO TO 3.

3.

TROUBLE DIAGNOSIS FOR SYMPTOM

Perform the diagnosis by symptom. Refer to 

STC-20, "Description"

.

>> 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

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< SYSTEM DESCRIPTION >

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SYSTEM DESCRIPTION

EPS SYSTEM

System Diagram

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CONTROL DIAGRAM

System Description

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• The EPS system controls the power steering solenoid valve

through the power steering control unit.

• 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 occurring in “2R” and “3R”. This

results in a light steering force because of high pressure.

During High-speed Operation

JSGIA0119GB

AWGIA0089GB

JSGIA0020GB

STC-4

< SYSTEM DESCRIPTION >

EPS SYSTEM

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 occurring in “3R” and results in a

heavy steering force.

Component Parts Location

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JSGIA0021GB

AWGIA0090ZZ

EPS SYSTEM

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Component Description

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1.

Power steering control unit M59 
(view with glove box removed)

2.

Power steering solenoid valve E14

Component parts

Function

Power steering control unit

• Signals from various sensors control the driving voltage to the power steering solenoid valve.
• The power steering control unit controls the driving voltage to the power steering solenoid valve 

for maintaining the power steering assist force when the fail-safe function is activated. (The en-
gine speed signals control EPS system if any vehicle speed signal error is detected.)

Combination meter

Refer to 

STC-13, "Description"

.

ECM

Refer to 

STC-10, "Description"

.

Power steering solenoid valve

Refer to 

STC-7, "Description"

.