Infiniti M35/M45 Y50. Manual - part 1126

AWD SYSTEM

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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.

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Transmission torque to front wheels is determined according
to command current.

AWD CONTROL UNIT

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

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Self-diagnosis can be done with CONSULT-II.

SDIA2270E

SDIA1844E

SDIA3133E

TF-12

AWD SYSTEM

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 Diagram

NDS000DD

Condition

AWD warning lamp

Lamp check

Turns ON when ignition switch is turned ON. Turns OFF 

approx. 1 second after engine start.

AWD system malfunction

ON

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 tires

Slow flashing: 1 time/2 seconds

(Continuing to flash until turning ignition switch OFF)

Other than above (system normal)

OFF

SDIA3134E

AWD SYSTEM

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COMPONENTS FUNCTION DESCRIPTION

CAN Communication

NDS000DE

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-50, "CAN System Specification Chart"

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Component parts

Function

AWD control unit

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

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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

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

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

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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.

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Vehicle speed signal

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Stop lamp switch signal (brake signal)

ECM

Transmits the following signals via CAN communication to AWD control unit.

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Accelerator pedal position signal

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Engine speed signal

Unified meter and A/C amp.

Transmits conditions of parking brake switch via CAN communication to AWD control unit.

TF-14

TROUBLE DIAGNOSIS

TROUBLE DIAGNOSIS

PFP:00004

Fail-Safe Function

NDS000DF

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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.

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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 Diagnosis

NDS000DG

BASIC CONCEPT

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

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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”.

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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.

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After completing diagnosis, always erase diagnostic memory.
Refer to 

TF-22, "How to Erase Self-Diagnostic Results"

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

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