INFINITI FX35 2004 Service Manual

TF-10
AWD SYSTEM
Revision: 2004 November 2004 FX35/FX45
ELECTRIC CONTROLLED COUPLING
Operation principle
1. AWD control unit supplies command current to electric controlled coupling (AWD solenoid).
2. Control clutch is engaged by electromagnet and torque is detected in control clutch.
3. The cam operates in response to control clutch torque and applies pressure to main clutch.
4. Main clutch transmits torque to front wheels according to pressing power.

Transmission torque to front wheels is determined according
to command current.
AWD CONTROL UNIT

Controls distribution of drive power between rear-wheel drive
(0:100) and AWD (50:50) conditions according to signals from
sensors.

Self-diagnosis can be done with CONSULT-II.
SDIA2270E
SDIA1844E
SDIA2273E

AWD SYSTEM
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Revision: 2004 November 2004 FX35/FX45
AWD WARNING LAMP
Turns ON when there is a malfunction in AWD system. It indicates that fail-safe mode is engaged and vehicle
change to rear-wheel drive or shifting driving force-AWD (Front-wheels still have some driving torque).
Also turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF approximately for 1
seconds after the engine starts if system is normal.
AWD Warning Lamp Indication
System DiagramADS000RX
Condition AWD warning lamp
Lamp checkTurns ON when ignition switch is turned ON. Turns OFF
approx. 1 second after engine start.
AWD system malfunctionON
Protection function is activated due to heavy load to electric con-
trolled coupling. (AWD system is not malfunctioning and AWD system
changes to 2WD mode.)Rapid flashing: 2 times/second
(Flashing in approx. 1 minute and then turning OFF.)
Large difference in diameter of front/rear tiresSlow flashing: 1 time/2 seconds
(Continuing to flash until turning ignition switch OFF)
Other than above (system normal) OFF
SDIA2160E

TF-12
AWD SYSTEM
Revision: 2004 November 2004 FX35/FX45
COMPONENTS FUNCTION DESCRIPTION
CAN CommunicationADS000RY
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
For details, refer to LAN-6, "
CAN Communication Unit" .
Component parts Function
AWD control unit

Controls driving force distribution by signals from each sensor and switch from rear wheel driving
mode (0:100) to AWD mode (50:50).

2WD mode is available by fail-safe function if malfunction is detected in AWD system.
Wheel sensors Detects wheel speed.
AWD solenoid Controls electric controlled coupling by command current from AWD control unit.
Electric controlled coupling Transmits driving force to front final drive.
AWD warning lamp

Illuminates if malfunction is detected in electrical system of AWD system.

There is 1 blink in 2 seconds if rotation difference of front wheels and rear wheels is large.

There are 2 blinks in 1 second if load is still applied to driving parts.
ABS actuator and electric unit
(control unit)Transmits the following signals via CAN communication to AWD control unit.

Vehicle speed signal

Stop lamp switch signal (brake signal)
ECMTransmits the following signals via CAN communication to AWD control unit.

Accelerator pedal position signal

Engine speed signal
Unified meter and A/C amp. Transmits conditions of parking brake switch via CAN communication to AWD control unit.

TROUBLE DIAGNOSIS
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Revision: 2004 November 2004 FX35/FX45
TROUBLE DIAGNOSISPFP:00004
Fail-Safe FunctionADS000S1

If any malfunction occurs in AWD electrical system, and control unit detects the malfunction, AWD warn-
ing lamp on combination meter turns ON to indicate system malfunction.

When AWD warning lamp is ON, vehicle changes to rear-wheel drive or shifting driving force-AWD (Front-
wheels still have some driving torque).
How to Perform Trouble DiagnosisADS000S2
BASIC CONCEPT

To perform trouble diagnosis, it is the most important to have understanding about vehicle systems (con-
trol and mechanism) thoroughly.

It is also important to clarify customer complaints before inspec-
tion.
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.
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".

It is essential to check symptoms right from the beginning in
order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms 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 repairing with-
out any symptom diagnosis, you cannot judge if malfunctions
have actually been eliminated.

After completing diagnosis, always erase diagnostic memory.
Refer to TF-22, "
How to Erase Self-diagnostic Results" .

For intermittent malfunctions, move harness or harness connec-
tor by hand. Then check for poor contact or reproduced open circuit.
SEF233G
SEF234G

TF-14
TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
Location of Electrical PartsADS000ST
SDIA2272E

TROUBLE DIAGNOSIS
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Revision: 2004 November 2004 FX35/FX45
Circuit DiagramADS000RZ
TDWM0015E

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TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
Wiring Diagram — AWD —ADS000S0
TDWM0012E

TROUBLE DIAGNOSIS
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Revision: 2004 November 2004 FX35/FX45
TDWM0016E

TF-18
TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
TDWM0017E

TROUBLE DIAGNOSIS
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Revision: 2004 November 2004 FX35/FX45
Trouble Diagnosis Chart for SymptomsADS000S3
If AWD warning lamp turns ON, perform self-diagnosis. Refer to TF-21, "SELF-DIAG RESULT MODE" .
NOTE:
Light tight-corner braking symptom may occur depending on driving conditions. This is not malfunction.
AWD Control Unit Input/Output Signal Reference ValuesADS000S4
AWD CONTROL UNIT INSPECTION TABLE
Specifications with CONSULT-II
Symptom Condition Check items Reference page
AWD warning lamp does not turn ON when
the ignition switch is turned to ON.
(AWD warning lamp check)Ignition switch: ONCAN communication line
TF-32
Unified meter and A/C amp.
Unified meter control unit
AWD warning lamp does not turn OFF sev-
eral seconds after engine started.Engine runningCAN communication line
TF-32
Power supply and ground for AWD con-
trol unit
Unified meter and A/C amp.
Unified meter control unit
AWD solenoid
AWD actuator relay (integrated in AWD
control unit)
Wheel sensor
Heavy tight-corner braking symptom occurs
when the vehicle is driven and the steering
wheel is turned fully to either side after the
engine is started. (See NOTE.)

While driving

Steering wheel is
turned fully to either
sidesCAN communication line
TF-34Accelerator pedal position signal
AWD solenoid
Mechanical malfunction of electric con-
trolled coupling (clutch sticking etc.)
Vehicle does not enter AWD mode even
though AWD warning lamp turned to OFF.While drivingAWD solenoid
TF-35
Mechanical malfunction of electric con-
trolled coupling (Mechanical engage-
ment of clutch is not possible.)
While driving, AWD warning lamp flashes
rapidly. (When flashing in approx. 1 minute
and then turning OFF.)
Rapid flashing: 2 times/secondWhile drivingProtection function is activated due to
heavy load to electric controlled cou-
pling. (AWD system is not malfunction-
ing. Also, optional distribution of torque
sometimes becomes rigid before lamp
flashes rapidly, but it is not malfunction.)TF-36
While driving, AWD warning lamp flashes
slowly. (When continuing to flash until turn-
ing ignition switch OFF)
Slow flashing: 1 time/2 seconds
While driving

Vehicle speed: 20 km/h
(12 MPH) or moreTire size is different between front and
rear of vehicle.TF-36
Monitored item [Unit] Content Condition Display value
FR RH SENSOR [km/h] or [mph]Wheel speed (Front wheel
right)Vehicle stopped 0.00 km/h (0.00 mph)
Vehicle running
CAUTION:
Check air pressure of tire under
standard condition.Approximately equal to
the indication on speed-
ometer (Inside of ±10%)
FR LH SENSOR [km/h] or [mph]Wheel speed (Front wheel
left)Vehicle stopped 0.00 km/h (0.00 mph)
Vehicle running
CAUTION:
Check air pressure of tire under
standard condition.Approximately equal to
the indication on speed-
ometer (Inside of ±10%)