control INFINITI M35 2007 Factory Service Manual

SYSTEM DESCRIPTION
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[EPS]SYSTEM DESCRIPTIONPFP:00000
ComponentsNGS000DT
Components (Models with Rear Active Steer)NGS000DU
Electronically Controlled Power Steering System FunctionNGS000DV

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.

For the models with RAS (Rear Active Steer), RAS control unit
performs the same control as power steering control unit. For
schematic, refer to STC-20, "
Schematic" and trouble diagnosis,
refer to STC-47, "
Diagnosis Chart by Symptom 2" .
SGIA1056E
SGIA1094E
SST696CA

STC-4
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SYSTEM DESCRIPTION
Revision: 2007 April2007 M35/M45
Fail-Safe FunctionNGS000DW
When the fail-safe function operate, it controls power steering sole-
noid valve by the engine speed as shown in the figure and maintains
the steering force.
FAIL-SAFE INPUT/CANCEL CONDITIONS
CAUTION:
Fail-safe function is activated when the engine runs at 1,500 rpm or higher for 10 seconds with the vehicle stopped. This is
normal and the fail-safe function is automatically deactivated when a vehicle speed signal of 2 km/h (1.2 MPH) or higher is
input or the ignition switch is turned OFF.
SGIA0411E
Input conditions Cancel conditions
When vehicle runs at an engine speed of 1,500 rpm or higher and no vehicle speed signal
is received for 10 seconds.

A vehicle speed of 2 km/h (1.2 MPH) or
more is input.

Turn the ignition switch ON after turn-
ing it OFF. The continuous vehicle speed signal 30 km/h (19 MPH) or more suddenly drops to less
than 2 km/h (1.2 MPH) within 1.4 seconds.

TROUBLE DIAGNOSIS
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TROUBLE DIAGNOSISPFP:00004
How to Perform Trouble DiagnosisNGS000DX
BASIC CONCEPT

The most important point to perform trouble diagnosis is to understand systems (control and mechanism)
in vehicle thoroughly.

It is also important to clarify customer complaints before inspec-
tion.
First of all, reproduce symptom, and understand it fully.
Ask customer about his/her complaints carefully. In some cases,
they will be necessary to check symptom by driving vehicle with
customer.
CAUTION:
Customers are not professionals. Do not assume “maybe
customer means...” or “maybe customer mentioned this
symptom”.

It is essential to check symptoms right from beginning in order to
repair a malfunction completely.
For an intermittent malfunction, it is important to reproduce
symptom based on interview with customer and past examples.
Do not perform inspection on ad hoc basis. Most intermittent
malfunctions are caused by poor contacts. In this case, it will be
effective to shake suspected harness or connector by hand.
When repairs are performed without any symptom check, no
one can judge if malfunction has actually been eliminated.

Always read “GI General Information” to confirm general precau-
tions. Refer to GI-4, "
General Precautions" .
Component Parts LocationNGS000DY
SEF234G
SEF233G
1. Power steering control unit
(Back of center console assembly)2. Power steering solenoid valve
SGIA1105J

STC-8
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Control Unit Input/Output Signal StandardNGS000E0
STANDARD BY CIRCUIT TESTER AND OSCILLOSCOPE
CAUTION:
When checked using a circuit tester for voltage measurement, connector terminals should not be
forcefully extended.
Te r m i n a l
Measuring
pointMeasuring condition Standard
+ (wire color) –
1 (GR)
GroundIGN Ignition switch ON. Battery voltage (Approx. 12 V)
2 (B) Ground — —
3 (L)Vehicle speed
signal
(2-pulse)At 40 km/h (25MPH)
5 (Y)Engine
speed signalAt idle after warming up
At approx. 2,000 rpm
7 (G)Power steer-
ing solenoid
valveNormal
(Vehicle speed)0 km/h (0 MPH) Approx. 4.4 - 6.6 V
100 km/h (62 MPH) Approx. 2.4 - 3.6 V
In fail-safe mode
(Engine speed)0 - 1,500 rpm Approx. 4.4 - 6.6 V
1,500 - 3,000 rpm Approx. 3.5 V
More than 3,000 rpm Approx. 2.1 V
ELF1080D
PBIA3654J
PBIA3655J

TROUBLE DIAGNOSIS
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For Fast and Accurate Trouble DiagnosisNGS000E1
Check the following items with the vehicle stopped

Is air pressure and size of tires proper?

Is the specified part used for the steering wheel?

Is control unit a genuine part?

Are there any fluid leakage from steering gear assembly, power steering oil pump, and hydraulic pipes,
etc? Refer to PS-8, "
Checking Fluid Leakage" .

Is the fluid level proper? Refer to PS-8, "Checking Fluid Level" .

Is the wheel alignment adjusted properly? Refer to FSU-6, "Wheel Alignment Inspection" (2WD), FSU-24,
"Wheel Alignment Inspection" (AWD).

Are there any damage or modification to suspension or body resulting in increased weight or altered
ground clearance?

Check each link installation condition of suspension and axle.

Check each connector connection condition.
Check the following items while driving the vehicle

Check conditions when the malfunction occurred (5W 1H).

Is the engine condition normal?
Basic InspectionNGS000E2
POWER SUPPLY CIRCUIT TERMINAL LOOSENESS AND BATTERY
Check battery terminals for looseness on both positive and negative ones and ground connection. Also make
sure that battery voltage does not drop.
Inspection: Power Steering Control Unit Power Supply Circuit and GroundNGS000E3
1. CHECK POWER STEERING CONTROL UNIT CONNECTOR
Turn ignition switch OFF, disconnect power steering control unit harness connector, and check terminal for
deformation, disconnection, looseness, etc.
OK or NG
OK >> GO TO 2.
NG >> Connector terminal connection is loose, damaged, open, or shorted. Repair or replace the termi-
nal.
2. CHECK POWER STEERING CONTROL UNIT GROUND CIRCUIT
Disconnect power steering control unit harness connector M8, and
then check continuity between power steering control unit harness
connector M8 and ground.
OK or NG
OK >> GO TO 3.
NG >> Ground circuit open or shorted. Repair or replace any
inoperative parts. Terminal 2 – Ground : Continuity exist.
SGIA1231E

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TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
3. CHECK POWER STEERING CONTROL UNIT POWER SUPPLY CIRCUIT
Turn ignition switch ON, and then check voltage between power
steering control unit harness connector M8 and ground.
OK or NG
OK >> Power supply and ground circuit are normal.
NG >> Power supply circuit open or shorted. Repair or replace
any inoperative parts.
Symptom: The Steering Force Does Not Change Smoothly According to the
Vehicle Speed
NGS000E4
Heavy steering force with the static steering/light steering force during high-speed driving
1. POWER STEERING SOLENOID VALVE SIGNAL INSPECTION 1
1. Start engine.
2. Change the vehicle speed from 0 to 100 km/h (0 to 62 MPH)
slowly, and then check voltage between power steering control
unit harness connector M8 and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 7.
2. POWER STEERING SOLENOID VALVE SIGNAL INSPECTION 2
1. Activate fail-safe function by running the engine speed at 1,500 rpm or higher for 10 seconds with the
vehicle stopped.
2. Change the engine speed to the idling, to approximately 1,600
rpm, and to approximately 3,000 rpm slowly, and then check
voltage between power steering control unit harness connector
M8 and ground.
OK or NG
OK >> GO TO 3.
NG >> GO TO 8.
3. CHECK POWER STEERING SOLENOID VALVE CONNECTOR
Turn ignition switch OFF, disconnect power steering solenoid valve harness connector, and check terminal for
deformation, disconnection, looseness, etc.
OK or NG
OK >> GO TO 4.
NG >> Harness or connector open or shorted. Repair or replace any inoperative parts.Terminal 1 – ground : Battery voltage (Approx. 12 V)
SGIA1232E
Terminal 7 – ground : The voltage has changed from
approximately 4.4 - 6.6 V to
approximately 2.4 - 3.6 V
SGIA1233E
Terminal 7 – ground : The voltage has changed from
approximately 5.5 V to approxi-
mately 2.1 V step-by-step.
SGIA1233E

TROUBLE DIAGNOSIS
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4. CHECK POWER STEERING SOLENOID VALVE POWER SUPPLY CIRCUIT
Check continuity between power steering control unit harness con-
nector M8 and power steering solenoid valve harness connector F25
(VQ35DE), E211 (VK45DE).
OK or NG
OK >> GO TO 5.
NG >> Open or short in harness. Repair or replace any inoper-
ative parts.
5. CHECK POWER STEERING SOLENOID VALVE GROUND CIRCUIT
Check continuity between power steering solenoid valve harness
connector F25 (VQ35DE), E211 (VK45DE) and ground.
OK or NG
OK >> GO TO 6.
NG >> Open or short in harness. Repair or replace any inoper-
ative parts.
6. CHECK POWER STEERING SOLENOID VALVE
Apply voltage power steering solenoid valve connector, and then
make sure that the operating sound (clicking sound) is heard.
OK or NG
OK >> Perform steering wheel turning force inspection. Refer
to PS-10, "
CHECKING STEERING WHEEL TURNING
FORCE" .
NG >> Power steering solenoid valve is inoperative. Replace.
Power steering control unit Power steering solenoid valve Continuity
Terminal 7 Terminal 1 Yes
SGIA1235E
Terminal 2 – Ground : Continuity exist.
SGIA1236E
Terminal 1 (+) - 2 (–) : Operating sound is heard.
SGIA1284E

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Revision: 2007 April2007 M35/M45
7. CHECK VEHICLE SPEED SIGNAL CIRCUIT
Change the vehicle speed, and then check voltage waveform
between power steering control unit harness connector M8 and
ground.
OK or NG
OK >> Power steering control unit is inoperative. Replace it.
NG >> Check the following systems and replace if necessary.

Harness between unified meter & A/C amp and power steering control unit.

Unified meter & A/C amp and vehicle speed signal circuit Refer to DI-28, "UNIFIED METER
AND A/C AMP" .
8. CHECK ENGINE SPEED SIGNAL CIRCUIT
Warm up the engine, and then check voltage waveform between
power steering control unit harness connector M8 and ground when
the engine speed is the idling and at approximately 2,000 rpm.
OK or NG
OK >> Power steering control unit is inoperating. Replace it.
NG >> Check the following systems and replace if malfunction is detected.

Harness between ECM and power steering control unit

ECM engine speed signal circuit. Refer to EC-826, "CONSULT-II Function (ENGINE)" .
Terminal 3 – GroundRepeat Approx. 0 V and approx. 5 V
SGIA1237EELF1080D
Terminal 5 – GroundAt Idle
Approx. 2,000 rpmSGIA1289EPBIA3654J
PBIA3655J

STC-16
[RAS]
SYSTEM DESCRIPTION
Revision: 2007 April2007 M35/M45
SYSTEM DESCRIPTIONPFP:00000
ComponentsNGS000E8
RAS (Rear Active Steer) FunctionNGS000E9
A. RAS control unit B. Model following control C. Target vehicle dynamics model
D. Rear wheel steering angle com-
mand value operationE. Rear wheel steering angle servo F. Vehicle speed signal (CAN)
G. Steering angle signal (CAN) H. Vehicle speed sensor I. Steering angle sensor
J. RAS actuator assembly
SGIA1241E
Part name Function
RAS control unit

Calculate the vehicle speed signal from CAN communication and the signals from steering
angle sensor and rear wheel steering angle sensor by a computer, and then control the rear
wheel steering angle.

Fail-safe function is activated when the electrical system is malfunctioning. The output signal
to the actuator is turned OFF during this mode. At that time, the RAS warning lamp illumi-
nates and indicates the system is malfunctioning.

It performs the communication control function with other control units via CAN communica-
tion.

This enables system diagnosis with CONSULT-II.
RAS actuatorThe efficiency of the rear wheel steer improves by locating the electric motor actuator into the
lower link of rear suspension.
Steering angle sensor

Measure the steering angle and send it to RAS control unit via CAN communication.

It is shared with the steering angle sensor for VDC.
Rear wheel steering angle sensor

It sends the rear wheel steering angle status to RAS control unit. The accuracy of rear wheel
steer improves by comparing the vehicle speed signal from CAN communication with the
rear wheel steering angle target value calculated from the wheel angle sensor signal, and it
controls them.

There are 2 types of rear wheel steering angle sensors (main/sub). If one of them is malfunc-
tioning, the other operates the fail-safe mode and stops the control.
RAS warning lamp

It turns on when the fail-safe function is operated and indicates that a RAS control malfunc-
tion has occurred.

It turns on when ignition switch turns on and turns off after the engine is started.

It indicates the suspect system by blinking when performing the self-diagnosis (without CON-
SULT-II).

SYSTEM DESCRIPTION
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Revision: 2007 April2007 M35/M45
Fail-Safe FunctionNGS000EA
In the event there is a malfunction with the electrical system, the RAS control is stopped and the fail-safe
mode is activated. At that time, it indicates the malfunction by turning the RAS warning lamp ON and stops the
rear wheel control.