Infiniti Q45. Manual - part 875

STC-3

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STC

MONITOR MODE  ............................................... 80
RAS CONTROL UNIT TERMINALS AND REF-
ERENCE VALUE ................................................. 80
DIAGNOSTIC PROCEDURE .............................. 80

Component Inspection  ........................................... 82

RAS MOTOR  ...................................................... 82
RAS MOTOR RELAY  .......................................... 82
NOISE SUPPRESSOR  ....................................... 83
REAR WHEEL STEERING ANGLE SENSOR .... 83
POWER STEERING SOLENOID VALVE ............ 84
STOP LAMP SWITCH  ........................................ 84

TROUBLE DIAGNOSIS FOR SYMPTOMS .............. 85

RAS Warning Lamp Does Not Turn ON for Approx. 
1 Second When The Igniting Switch Is Turned to ON 

... 85

DIAGNOSTIC PROCEDURE .............................. 85

The Steering Force of Steering Wheel Is Not 
Changed Smoothly According to the Vehicle Speed 

... 87

SYMPTOM: ......................................................... 87
DIAGNOSTIC PROCEDURE .............................. 87

Hard Steering When Fully Turning the Steering 

Wheel ..................................................................... 88

DIAGNOSTIC PROCEDURE  .............................. 88

Light Steering When Driving at a High Speed  ........ 89

DIAGNOSTIC PROCEDURE  .............................. 89

CONTROL UNIT  ....................................................... 90

Removal and Installation  ........................................ 90

REMOVAL ........................................................... 90
INSTALLATION ................................................... 90

REAR ACTIVE STEER  ............................................. 91

Removal and Installation  ........................................ 91

COMPONENTS ................................................... 91
REMOVAL ........................................................... 91
INSTALLATION ................................................... 91

Disassembly and Assembly .................................... 92

COMPONENTS ................................................... 92
DISASSEMBLY ................................................... 92
INSPECTION AFTER DISASSEMBLY ................ 92
ASSEMBLY ......................................................... 92
ADJUSTMENT AFTER ASSEMBLING  ............... 92

STC-4

[WITHOUT REAR ACTIVE STEER]

PRECAUTIONS

[WITHOUT REAR ACTIVE STEER]

PRECAUTIONS

PFP:00001

Precautions for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT 
BELT PRE-TENSIONER”

NGS0005P

The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.

WARNING:

●

To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN/INFINITI dealer.

●

Improper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the SRS section.

●

Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or
harness connectors.

Precautions

NGS0005Q

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Before connecting or disconnecting the active damper sus-
pension control unit harness connector, turn ignition
switch “OFF” and disconnect the battery cable from the
negative terminal. Battery voltage is applied to active
damper suspension control unit even if ignition switch is
turned “OFF”.

●

When connecting or disconnecting pin connectors into or
from active damper suspension control unit, take care not
to damage pin terminals (bend or break).
When connecting pin connectors make sure that there are
not any bends or breaks on active damper suspension con-
trol unit pin terminals.

●

Before replacing active damper suspension control unit,
perform active damper suspension control unit input/out-
put signal inspection and make sure whether active damper
suspension control unit functions properly or not. Refer to

STC-12, "Active Damper Suspension Control Unit Input/
Output Signal Reference Values"

 .

SEF289H

SEF291H

SDIA1848E

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

STC-5

[WITHOUT REAR ACTIVE STEER]

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STC

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

PFP:28500

Power Steering Control Diagram

NGS000CQ

Operation Principle

NGS000CV

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.

1.

Speed sensor

2.

Active damper suspension 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

SGIA1389E

SGIA1392E

STC-6

[WITHOUT REAR ACTIVE STEER]

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

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.

System Description

NGS0004G

DESCRIPTION

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Electrically controlled power steering system is controlled by active damper suspension control unit.

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The system controls power steering solenoid valve by changing supply current to the power steering sole-
noid valve depending on vehicle speed.

POWER STEERING SOLENOID VALVE

●

Vehicle speed sensing electronically controlled power steering
(that properly controls the steering force by the vehicle speed)
has been adopted. When it is normal, it controls the power
steering solenoid valve according to the vehicle speed as shown
in the figure and makes the steering force proper.

●

Power steering solenoid valve becomes full throttle when the
power steering solenoid valve voltage is 2.5 V, and totally-
enclosed when the voltage is 5.5 V.

CONTROL UNIT

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The active damper suspension control unit (1) controls power
steering solenoid valve.

●

Self-diagnosis can be done.

SGIA1393E

SST696CA

SGIA1394E