Infiniti QX56 (Z62). Manual - part 1263

 

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Infiniti QX56 (Z62). Manual - part 1263

 

 

STC-4

< SYSTEM DESCRIPTION >

COMPONENT PARTS

SYSTEM DESCRIPTION

COMPONENT PARTS

Component Parts Location

INFOID:0000000006256115

Component Description

INFOID:0000000006256116

Power Steering Control Unit

INFOID:0000000006256117

• 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 maintain-

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

Power Steering Solenoid Valve

INFOID:0000000006256118

Power steering solenoid valve controls the power steering oil pressure in the gear housing assembly.

1.

ECM
Refer to 

EC-16, "Component Parts 

Location"

.

2.

Combination meter
Refer to 

MWI-6, "METER SYSTEM : 

Component Parts Location"

.

3.

Power steering control unit

4.

Power steering solenoid valve

A.

Glove box assembly removed

B.

Steering gear assembly

JPGIB0006ZZ

Component parts

Reference/Function

Power steering control unit

STC-4, "Power Steering Control Unit"

Power steering solenoid valve

STC-4, "Power Steering Solenoid Valve"

Combination meter

Transmits vehicle speed signal to power steering control unit.

ECM

Transmits engine speed signal to power steering control unit.

SYSTEM

STC-5

< SYSTEM DESCRIPTION >

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STC

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SYSTEM

EPS SYSTEM

EPS SYSTEM : System Description

INFOID:0000000006256119

• 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.

CONTROL DIAGRAM

CROSS-SECTIONAL VIEW

JPGIB0021GB

JPGIB0017GB

SGIA1389E

STC-6

< SYSTEM DESCRIPTION >

SYSTEM

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.

EPS SYSTEM : Fail-Safe 

INFOID:0000000006256120

EPS system

• EPS system enters the fail-safe mode (that allows the steering

force to be controlled without impairing the drivability) if any of the
input/output values to/from EPS system (power steering control
unit) deviate from the standard range.

• 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 engine
speed signals control EPS system if any vehicle speed signal error
is detected.)

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

JSGIA0020GB

JSGIA0021GB

JPGIB0022GB

SYSTEM

STC-7

< SYSTEM DESCRIPTION >

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Error area and root cause

Cancel condition

Engine speed is 1,500 rpm or more and there is no vehicle speed signal input for 
over 10 seconds during vehicle travel.

• When a vehicle speed signal of 2 km/h (1.2 

MPH) or more is inputted.

• Ignition switch is turned OFF to ON.

Vehicle speed signal has abruptly dropped from 30 km/h (19 MPH) or more to 2 
km/h (1.2 MPH) or less within 1.4 seconds.

 

 

 

 

 

 

 

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