STEERING

SECTION
STEERING CONTROL SYSTEM
STC B

E
CONTENTS
BASIC INSPECTION .................................... 2 Diagnosis Procedure ...............................................11 F

DIAGNOSIS AND REPAIR WORK FLOW ......... 2 ECU DIAGNOSIS ......................................... 13

Work Flow ................................................................. 2
POWER STEERING CONTROL UNIT .............. 13 STC
FUNCTION DIAGNOSIS ............................... 3 Reference Value ......................................................13
Wiring Diagram - ELECTRONICALLY CON-
EPS SYSTEM ...................................................... 3 TROLLED POWER STEERING SYSTEM - ............15 H
System Diagram ........................................................ 3 Fail-Safe ..................................................................17
System Description ................................................... 3
Component Parts Location ........................................ 5 SYMPTOM DIAGNOSIS .............................. 19 I
Component Description ............................................. 5
UNBALANCE STEERING WHEEL TURNING
COMPONENT DIAGNOSIS .......................... 6 FORCE (TORQUE VARIATION) ....................... 19
Description ...............................................................19 J
POWER SUPPLY AND GROUND CIRCUIT ....... 6 Diagnosis Procedure ...............................................19
Description ................................................................ 6
Diagnosis Procedure ................................................. 6 PRECAUTION .............................................. 20 K
POWER STEERING SOLENOID VALVE ........... 7 PRECAUTIONS ................................................. 20
Description ................................................................ 7 Precaution for Supplemental Restraint System
Component Function Check ...................................... 7 (SRS) "AIR BAG" and "SEAT BELT PRE-TEN- L
Diagnosis Procedure ................................................. 7 SIONER" .................................................................20
Component Inspection .............................................. 8 Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect ...................................20 M
ENGINE SPEED SIGNAL CIRCUIT .................... 9
Description ................................................................ 9 ON-VEHICLE REPAIR ................................. 21
Diagnosis Procedure ................................................. 9
POWER STEERING CONTROL UNIT .............. 21 N
VEHICLE SPEED SIGNAL CIRCUIT .................11 Exploded View .........................................................21
Description .............................................................. 11 Removal and Installation .........................................21
O

Revision: 2008 October STC-1 2009 370Z

 DIAGNOSIS AND REPAIR WORK FLOW
< BASIC INSPECTION >
BASIC INSPECTION
DIAGNOSIS AND REPAIR WORK FLOW
Work Flow INFOID:0000000004470780

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. Power steering fluid leakage and check the power steering fluid level. Refer to ST-7, "Inspection".
2. Check the drive belt tension. Refer to EM-13, "Checking".
3. Check the power steering gear for damages, cracks and fluid leakage. Refer to ST-24, "Inspection".
4. Check the relief oil pressure. Refer to ST-30, "Inspection".

>> GO TO 3.
3.DIAGNOSIS CHART BY SYMPTOM
Perform the diagnosis by symptom. Refer to STC-19, "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.

Revision: 2008 October STC-2 2009 370Z

 EPS SYSTEM
< FUNCTION DIAGNOSIS >
FUNCTION DIAGNOSIS A
EPS SYSTEM
System Diagram INFOID:0000000004499020
B

CONTROL DIAGRAM
C

STC

H
JSGIA0119GB

CROSS-SECTIONAL VIEW
I

N
JSGIA0376ZZ

1. Combination meter 2. Power steering control unit 3. Power steering solenoid valve
O
4. Steering gear assembly 5. Gear housing assembly 6. Gear sub-assembly
7. Pinion 8. Power steering oil pump 9. Reservoir tank

System Description INFOID:0000000004470782 P

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

Revision: 2008 October STC-3 2009 370Z

 EPS SYSTEM
< FUNCTION DIAGNOSIS >
• The valve driving voltage to control the power steering solenoid
valve varies according to the vehicle speed.

JSGIA0113GB

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

JSGIA0020GB

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 (When Turning The Steering Wheel To The Right.)

JSGIA0021GB

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.

Revision: 2008 October STC-4 2009 370Z

 EPS SYSTEM
< FUNCTION DIAGNOSIS >
Component Parts Location INFOID:0000000004470783

STC

JSGIA0581ZZ
I
1. Power steering solenoid valve 2. Power steering control unit
A. Steering gear assembly B. Glove box assembly removed
J
: Vehicle front

Component Description INFOID:0000000004499021

K

Component parts Reference/Function

• Signals from various sensors control the driving voltage to the power steering solenoid valve.
L
• The power steering control unit controls the driving voltage to the power steering solenoid valve
Power steering control unit
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.) M
Combination meter STC-11, "Description"
ECM STC-9, "Description"
Power steering solenoid valve STC-7, "Description" N

Revision: 2008 October STC-5 2009 370Z

 POWER SUPPLY AND GROUND CIRCUIT
< COMPONENT DIAGNOSIS >
COMPONENT DIAGNOSIS
POWER SUPPLY AND GROUND CIRCUIT
Description INFOID:0000000004470785

Power supply to EPS system

Diagnosis Procedure INFOID:0000000004470786

1.CHECK POWER SUPPLY

1. Turn the ignition switch OFF.
2. Disconnect power steering control unit harness connector.
3. Check the voltage between power steering control unit harness connector and ground.

Power steering control unit

— Voltage
Connector Terminal
M108 3 Ground 0V

4. Turn the ignition switch ON.

CAUTION:
Never start the engine.
5. Check the voltage between power steering control unit harness connector and ground.

Power steering control unit

— Voltage
Connector Terminal
M108 3 Ground Battery voltage
Is the inspection result normal?
YES >> GO TO 2.
NO >> Check the following. If any items are damaged, repair or replace damaged parts.
• 10A fuse (#45) open
- Harness for short or open between ignition switch and power steering control unit harness con-
nector No. 3 terminal.
- Ignition switch. Refer to PCS-114, "Exploded View".
2.CHECK GROUND CIRCUIT
1. Turn the ignition switch OFF.
2. Check the continuity between power steering control unit harness connector and ground.

Power steering control unit

— Continuity
Connector Terminal
M108 6 Ground Existed
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK TERMINALS AND HARNESS CONNECTORS
Check the power steering control unit 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.

Revision: 2008 October STC-6 2009 370Z

 POWER STEERING SOLENOID VALVE
< COMPONENT DIAGNOSIS >
POWER STEERING SOLENOID VALVE
A
Description INFOID:0000000004470787

Power steering solenoid valve controls the power steering oil pressure in the gear housing assembly. B
Component Function Check INFOID:0000000004732436

1.CHECK POWER STEERING SOLENOID VALVE OPERATION C

Check changes in steering force from a halt condition to high-speed driving.
Is the inspection result normal?
D
YES >> INSPECTION END
NO >> Check the power steering solenoid valve. Refer to STC-7, "Diagnosis Procedure".
Diagnosis Procedure INFOID:0000000004470788 E

1.CHECK POWER STEERING SOLENOID VALVE SIGNAL

1. Turn the ignition switch OFF. F
2. Check the voltage between power steering control unit harness connector and ground.

Power steering control unit STC

— Condition Voltage (Approx.)
Connector Terminal
Vehicle speed: 0 km/h (0 MPH)
4.4 – 6.6 V H
M108 1 Ground (Engine is running)
Vehicle speed: 100 km/h (62 MPH) 2.4 – 3.6 V
Is the inspection result normal? I
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN POWER STEERING SOLENOID VALVE AND POWER STEERING CON- J
TROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector. K
3. Disconnect power steering control unit harness connector.
4. Check the continuity between power steering solenoid valve harness connector and the power steering
control unit harness connector. L

Power steering solenoid valve Power steering control unit

Continuity
Connector Terminal Connector Terminal M
1 1 Existed
F45 M108
2 5 Existed
N
5. Check the continuity between power steering control unit harness connector and ground.

Power steering control unit O

— Continuity
Connector Terminal
1
M108 Ground Not existed
5 P
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK POWER STEERING SOLENOID VALVE
Check the power steering solenoid valve. Refer to STC-8, "Component Inspection".

Revision: 2008 October STC-7 2009 370Z

 POWER STEERING SOLENOID VALVE
< COMPONENT DIAGNOSIS >
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace gear-sub assembly. Refer to ST-18, "Exploded View".
4.CHECK TERMINALS AND HARNESS CONNECTORS
• Check the power steering control unit pin terminals for damage or loose connection with harness connector.
• Check the power steering solenoid valve pin terminals for damage or loose connection with harness connec-
tor.
Is the inspection result normal?
YES >> Replace power steering control unit. Refer to STC-21, "Exploded View".
NO >> Repair or replace error-detected parts.
Component Inspection INFOID:0000000004470789

1.CHECK POWER STEERING SOLENOID VALVE

1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector.
3. Check resistance between power steering solenoid valve connector terminals.

Power steering solenoid valve

Resistance (Approx.)
Terminal
1 2 4–6Ω
4. Check power steering solenoid valve by listening for its operation sound while applying battery voltage to
power steering solenoid valve connector E207 terminals 1 (positive) and 2 (negative).
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace gear-sub assembly. Refer to ST-18, "Exploded View".

Revision: 2008 October STC-8 2009 370Z

 ENGINE SPEED SIGNAL CIRCUIT
< COMPONENT DIAGNOSIS >
ENGINE SPEED SIGNAL CIRCUIT
A
Description INFOID:0000000004470790

ECM sends engine speed signal to power steering control unit. B

Diagnosis Procedure INFOID:0000000004470791

1.PERFORM ECM SELF-DIAGNOSIS C

With CONSULT-III
1. Turn the ignition switch ON.
CAUTION: D
Never start the engine
2. Perform ECM self-diagnosis. Refer to EC-128, "CONSULT-III Function".
Is any DTC detected? E
YES >> Check the DTC.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN ECM AND POWER STEERING CONTROL UNIT F

1. Turn the ignition switch OFF.

2. Disconnect ECM harness connectors.
STC
3. Disconnect power steering control unit harness connector.
4. Check the continuity between ECM harness connector and power steering control unit harness connector.

H
ECM Power steering control unit
Continuity
Connector Terminal Connector Terminal
M107 110 M108 10 Existed I
5. Check the continuity between power steering control unit harness connector and ground.

Power steering control unit J

— Continuity
Connector Terminal
M108 10 Ground Not existed
K
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace error-detected parts. L
3.CHECK ENGINE SPEED SIGNAL (1)
1. Connect ECM harness connectors.
2. Turn the ignition switch ON. M
3. Check the signal between ECM harness connector and ground with oscilloscope.

Revision: 2008 October STC-9 2009 370Z

 ENGINE SPEED SIGNAL CIRCUIT
< COMPONENT DIAGNOSIS >

ECM
— Condition Voltage (Approx.)
Connector Terminal

Engine is running
• Warm-up condition
• Idle speed

JMBIA0076GB
M107 110 Ground

Engine is running
• Warm-up condition
• Engine speed: Approx. 2,000 rpm

JMBIA0077GB

Is the inspection result normal?

YES >> GO TO 4.
NO >> Replace ECM. Refer to EC-16, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT
(ECM) : Description".
4.CHECK ENGINE SPEED SIGNAL (2)
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.

Power steering control unit

— Condition Voltage (Approx.)
Connector Terminal

Engine is running
• Warm-up condition
• Idle speed

JMBIA0076GB
M108 10 Ground

Engine is running
• Warm-up condition
• Engine speed: Approx. 2,000 rpm

JMBIA0077GB

Is the inspection result normal?

YES >> GO TO 5.
NO >> Replace power steering control unit. Refer to STC-21, "Exploded View".
5.CHECK TERMINALS AND HARNESS CONNECTORS
• Check the power steering control unit pin terminals for damage or loose connection with harness connector.
• Check the ECM 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.

Revision: 2008 October STC-10 2009 370Z

 VEHICLE SPEED SIGNAL CIRCUIT
< COMPONENT DIAGNOSIS >
VEHICLE SPEED SIGNAL CIRCUIT
A
Description INFOID:0000000004499018

Combination meter sends vehicle speed signal to power steering control unit. B
Diagnosis Procedure INFOID:0000000004499019

1.PERFORM COMBINATION METER SELF-DIAGNOSIS C

With CONSULT-III
1. Turn the ignition switch ON.
2. Perform combination meter self-diagnosis. Refer to MWI-33, "CONSULT-III Function (METER/M&A)". D
Is any DTC detected?
YES >> Check the DTC.
NO >> GO TO 2. E

2.CHECK HARNESS BETWEEN COMBINATION METER AND POWER STEERING CONTROL UNIT
1. Turn the ignition switch OFF. F
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-
STC
ness connector.

Combination meter Power steering control unit

Continuity H
Connector Terminal Connector Terminal
M53 3 M108 8 Existed
5. Check the continuity between power steering control unit harness connector and ground. I

Power steering control unit

— Continuity J
Connector Terminal
M108 8 Ground Not existed
Is the inspection result normal? K
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK VEHICLE SPEED SIGNAL (1) L
1. Connect combination meter harness connector.
2. Check the combination meter input/output standard values. Refer to MWI-56, "Reference Value".
M
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace combination meter Refer to MWI-94, "Exploded View".
N
4.CHECK VEHICLE SPEED SIGNAL (2)
1. Turn the ignition switch OFF.
2. Connect power steering control unit harness connector. O
3. Check the signal between power steering control unit harness connector and ground with oscilloscope.

Revision: 2008 October STC-11 2009 370Z

 VEHICLE SPEED SIGNAL CIRCUIT
< COMPONENT DIAGNOSIS >

Power steering control unit

— Condition Voltage (Approx.)
Connector Terminal
NOTE:
The maximum voltage varies de-
pending on the specification (desti-
nation unit).
Vehicle speed: 40 km/h (25 MPH)
CAUTION:
M108 8 Ground
Check air pressure of tire under
standard condition.

JSNIA0015GB

Is the inspection result normal?

YES >> GO TO 5.
NO >> Replace power steering control unit. Refer to STC-21, "Exploded View".
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.

Revision: 2008 October STC-12 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >
ECU DIAGNOSIS A
POWER STEERING CONTROL UNIT
Reference Value INFOID:0000000004470794
B

TERMINAL LAYOUT
C

JSGIA0023ZZ
F
PHYSICAL VALUES

Terminal No.
Description
STC
(Wire color)
Condition Value (Approx.)
Input/
+ - Signal name
Output H
Vehicle speed: 0 km/h (0 MPH)
1 Power steering solenoid 4.4 – 6.6 V
Ground Output (Engine is running)
(LG) valve control voltage
Vehicle speed: 100 km/h (62 MPH) 2.4 – 3.6 V I
3 Ignition switch power Ignition switch: ON Battery voltage
Ground Input
(G) supply Ignition switch: OFF 0V
5 Power steering solenoid
J
Ground — Always 0V
(B) valve ground
6
Ground Ground — Always 0V K
(B)
NOTE:
The maximum voltage varies de-
pending on the specification L
(destination unit).
Vehicle speed: 40 km/h (25 MPH)
8 CAUTION:
Ground Vehicle speed signal Input
(L) Check air pressure of tire under M
standard condition.

N
JSNIA0015GB

Revision: 2008 October STC-13 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >
Terminal No.
Description
(Wire color)
Condition Value (Approx.)
Input/
+ - Signal name
Output

Engine is running
• Warm-up condition
• Idle speed

10 JMBIA0076GB
Ground Engine speed signal Input
(R)

Engine is running
• Warm-up condition
• Engine speed: Approx. 2,000 rpm

JMBIA0077GB

CAUTION:
When using circuit tester or oscilloscope to measure voltage for inspection, never forcibly extend any connector terminals.

Revision: 2008 October STC-14 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >
Wiring Diagram - ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM -
INFOID:0000000004470795 A

STC

JCGWA0200GB

Revision: 2008 October STC-15 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >

JCGWA0201GB

Revision: 2008 October STC-16 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >

STC

JCGWA0202GB

P
Fail-Safe INFOID:0000000004470796

EPS system

Revision: 2008 October STC-17 2009 370Z

 POWER STEERING CONTROL UNIT
< ECU DIAGNOSIS >
• 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.
NOTE:
The system enters the fail-safe mode if the engine speed remains
at 1,500 rpm or more for over 10 seconds while the vehicle is
stopped. This is normal.
• The fail-safe function is canceled when a vehicle speed signal of 2
km/h (1.2 MPH) or more is inputted or the ignition switch is turned
OFF→ON. EPS system restores the normal operation at that time.
JSGIA0368GB

Warn-
Mode DTC Detection point (malfunction part) Error area and root cause
ing lamp
• Engine speed is 1,500 rpm or more and there is no vehicle
speed signal input for over 10 seconds during vehicle travel.
Fail-safe — — Vehicle speed signal input • 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 sec-
onds.

Revision: 2008 October STC-18 2009 370Z

 UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIATION)
< SYMPTOM DIAGNOSIS >
SYMPTOM DIAGNOSIS A
UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIA-
TION)
B
Description INFOID:0000000004470797

• Hard steering when fully turning the steering wheel. C

• Light steering when driving at a high speed.
Diagnosis Procedure INFOID:0000000004470798

D
1.CHECK SYSTEM FOR POWER SUPPLY AND GROUND
Perform trouble diagnosis for power supply and ground. Refer to STC-6, "Diagnosis Procedure".
E
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair or replace error-detected parts.
F
2.CHECK SYSTEM FOR VEHICLE SPEED SIGNAL
Perform trouble diagnosis for vehicle speed signal. Refer to STC-11, "Diagnosis Procedure".
Is the inspection result normal? STC
YES >> GO TO 3.
NO >> Repair or replace error-detected parts.
3.CHECK SYSTEM FOR ENGINE SPEED SIGNAL H

Perform trouble diagnosis for engine speed signal. Refer to STC-9, "Diagnosis Procedure".
Is the inspection result normal? I
YES >> GO TO 4.
NO >> Repair or replace error-detected parts.
4.CHECK SYSTEM FOR POWER STEERING SOLENOID VALVE J
Perform trouble diagnosis for power steering solenoid valve. Refer to STC-7, "Diagnosis Procedure".
Is the inspection result normal?
K
YES >> Perform the symptom diagnosis for the steering system. Refer to ST-2, "NVH Troubleshooting
Chart".
NO >> Repair or replace error-detected parts.
L

Revision: 2008 October STC-19 2009 370Z

 PRECAUTIONS
< PRECAUTION >
PRECAUTION
PRECAUTIONS
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER" INFOID:0000000004495127

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 AIRBAG” and “SEAT BELT” of this
Service Manual.
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 performed by
an authorized NISSAN/INFINITI dealer.
• Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal
injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag
Module, see the “SRS AIRBAG”.
• Never use electrical test equipment on any circuit related to the SRS unless instructed to in this Ser-
vice Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or harness
connectors.
PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS
When working near the Airbag Diagnosis Sensor Unit or other Airbag System sensors while ignition switch is
ON or engine is running, never use air or electric power tools or strike near the sensor(s) with a hammer.
Heavy vibration may activate the sensor(s), deploy the airbag(s), possibly cause serious injury.
When using air or electric power tools or hammers, always turn OFF ignition switch, disconnect the battery,
and wait 3 minutes or more before performing any service.
Precaution Necessary for Steering Wheel Rotation after Battery Disconnect
INFOID:0000000004495128

NOTE:
• Before removing and installing any control units, first turn the push-button ignition switch to the LOCK posi-
tion, then disconnect both battery cables.
• After finishing work, confirm that all control unit connectors are connected properly, then re-connect both
battery cables.
• Always use CONSULT-III to perform self-diagnosis as a part of each function inspection after finishing work.
If a DTC is detected, perform trouble diagnosis according to self-diagnosis results.
This vehicle is equipped with a push-button ignition switch and a steering lock unit.
If the battery is disconnected or discharged, the steering wheel will lock and cannot be turned.
If turning the steering wheel is required with the battery disconnected or discharged, follow the procedure
below before starting the repair operation.
OPERATION PROCEDURE
1. Connect both battery cables.
NOTE:
Supply power using jumper cables if battery is discharged.
2. Turn the push-button ignition switch to ACC position.
(At this time, the steering lock will be released.)
3. Disconnect both battery cables. The steering lock will remain released with both battery cables discon-
nected and the steering wheel can be turned.
4. Perform the necessary repair operation.
5. When the repair work is completed, re-connect both battery cables. With the brake pedal released, turn
the push-button ignition switch from ACC position to ON position, then to LOCK position. (The steering
wheel will lock when the push-button ignition switch is turned to LOCK position.)
6. Perform self-diagnosis check of all control units using CONSULT-III.

Revision: 2008 October STC-20 2009 370Z

 POWER STEERING CONTROL UNIT
< ON-VEHICLE REPAIR >
ON-VEHICLE REPAIR A
POWER STEERING CONTROL UNIT
Exploded View INFOID:0000000004470801
B

STC

JSGIA0573ZZ
H
1. Steering member 2. Power steering control unit

: Vehicle front I
Removal and Installation INFOID:0000000004470802

J
REMOVAL
1. Remove glove box assembly. Refer to IP-11, "Exploded View".
2. Disconnect power steering control unit connector. K
3. Remove power steering control unit.
INSTALLATION
Install in the reverse order of removal. L

Revision: 2008 October STC-21 2009 370Z