Infiniti G37 Coupe. Manual - part 1257

C1684, C1685 4WAS MAIN CONTROL UNIT COMMUNICATION

STC-79

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

4.

Check the continuity between 4WAS front control unit harness connector and ABS actuator and electric
unit (control unit) harness connector.

5.

Check that 4WAS front control unit connector No. 14 terminal and No. 25 are connected properly and not
deformed.

Is the inspection result normal?

YES

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

NO

>> Repair or replace the harnesses and connectors. Refer to 

STC-176, "Precautions for Harness

Repair"

.

8.

CHECK 4WAS MAIN CONTROL UNIT CIRCUIT

1.

Turn the ignition switch OFF.

2.

Disconnect 4WAS main control unit harness connector.

3.

Disconnect ABS actuator and electric unit (control unit) harness connector.

4.

Check the continuity between 4WAS main control unit harness connector and ABS actuator and electric
unit (control unit) harness connector.

5.

Check that 4WAS main control unit connector No. 31 terminal and No. 32 are connected properly and not
deformed.

Is the inspection result normal?

YES

>> Replace 4WAS main control unit. Refer to 

STC-178, "Exploded View"

.

NO

>> Repair or replace the harnesses and connectors. Refer to 

STC-176, "Precautions for Harness

Repair"

.

Component Inspection [ABS Actuator and Electric Unit (Control Unit)]

INFOID:0000000001666372

1.

CHECK ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)

1.

Turn the ignition switch OFF.

2.

Remove ABS actuator and electric unit (control unit). Refer to

BRC-102, "Exploded View"

.

3.

Check the resistance between ABS actuator and electric unit (control unit) connector terminals.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace ABS actuator and electric unit (control unit).

Component Inspection (Yaw Rate/Side G Sensor)

INFOID:0000000001666373

1.

CHECK YAW RATE/SIDE G SENSOR

1.

Turn the ignition switch OFF.

2.

Remove yaw rate/side G sensor. Refer to 

BRC-104, "Exploded View"

.

3.

Check the resistance between yaw rate/side G sensor connector terminals.

4WAS front control unit

ABS actuator and electric 

unit (control unit)

Continuity

Connector

Terminal

Connector

Terminal

M42

14

E41

25

Existed

25

45

4WAS main control unit

ABS actuator and electric 

unit (control unit)

Continuity

Connector

Terminal

Connector

Terminal

B54

31

E41

45

Existed

32

25

ABS actuator and electric unit (control unit)

Resistance (Approx.)

Connector

Terminal

E41

25 – 45

120 

Ω

STC-80

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1684, C1685 4WAS MAIN CONTROL UNIT COMMUNICATION

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace yaw rate/side G sensor.

Special Repair Requirement

INFOID:0000000001666374

BEFORE REPLACING 4WAS FRONT CONTROL UNIT

• Record the self-diagnosis results (history).

CAUTION:

• Never erase the memory (history) of self-diagnosis results when replacing 4WAS front control unit

after diagnosis.

• Erase the memory of the self-diagnosis results (record) after printing out or recording all the val-

ues of “DATA MONITOR”.

BEFORE REPLACING 4WAS MAIN ACTUATOR

• Record the self-diagnosis results (history).

CAUTION:

• Never erase the memory (history) of self-diagnosis results when replacing 4WAS main control unit

after diagnosis.

• Erase the memory of the self-diagnosis results (record) after printing out or recording all the val-

ues of “DATA MONITOR”.

AFTER REPLACING 4WAS FRONT CONTROL UNIT

• Perform 4WAS front actuator adjustment after replacing 4WAS front control unit. Refer to 

STC-28, "4WAS

FRONT ACTUATOR NEUTRAL POSITION ADJUSTMENT : Special Repair Requirement (Pattern 3)"

.

Yaw rate/side G sensor

Resistance (Approx.)

Connector

Terminal

M143

2 – 3

120 

Ω

C1686 4WAS MAIN CONTROL UNIT

STC-81

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

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J

K

L

M

A

B

STC

N

O

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C1686 4WAS MAIN CONTROL UNIT

Description

INFOID:0000000001666375

• It transmits the value calculated by 4WAS main control unit to 4WAS front control unit with 4WAS communi-

cation line (line for 4WAS system). 4WAS front control unit controls 4WAS front actuator according to the
received command value.

DTC Logic

INFOID:0000000001666376

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

RECHECK DTC

With CONSULT-III

1.

Turn the ignition switch from OFF to ON.

2.

Perform 4WAS front control unit self-diagnosis.

Is DTC “C1686” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-81, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666377

1.

PERFORM SELF-DIAGNOSIS (4WAS FRONT CONTROL UNIT)

With CONSULT-III

Perform 4WAS front control unit self-diagnosis.

Is any DTC other than “C1686” detected?

YES

>> Check the error system.

NO

>> Perform 4WAS main control unit self-diagnosis.

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1686

4WAS MAIN ECU

An error is detected on 4WAS main control unit side.
(4WAS main control unit fail-safe mode)

4WAS main control unit 
fail-safe mode

STC-82

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

U1000, U1002 4WAS COMMUNICATION CIRCUIT

U1000, U1002 4WAS COMMUNICATION CIRCUIT

Description

INFOID:0000000001878358

• 4WAS front control unit and 4WAS main control unit transmit/receive information to/from each other for opti-

mum control of the 4WAS system with the specified 4WAS system line (4WAS communication line) between
4WAS front control unit and 4WAS main control unit.

• Be careful to repair wirings because 4WAS system specified line adopts twisted-pair wires. Refer to 

STC-

176, "Precautions for Harness Repair"

.

DTC Logic

INFOID:0000000001666379

DTC DETECTION LOGIC

*: Communication line between 4WAS front control unit and 4WAS main control unit

DTC CONFIRMATION PROCEDURE

1.

RECHECK DTC

With CONSULT-III

1.

Turn the ignition switch from OFF to ON.

2.

Perform 4WAS front control unit self-diagnosis.

Is DTC “U1000” or “U1002” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-82, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666380

1.

CHECK COMMUNICATION LINE (1)

1.

Turn the ignition switch OFF.

2.

Disconnect ABS actuator and electric unit (control unit) harness connector.

3.

Disconnect yaw rate/side G sensor harness connector.

4.

Disconnect 4WAS front control unit harness connector.

5.

Disconnect 4WAS main control unit harness connector.

6.

Check the continuity between ABS actuator and electric unit (control unit) harness connector and yaw
rate/side G sensor harness connector.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace the harnesses and connectors. Refer to 

STC-176, "Precautions for Harness

Repair"

.

2.

CHECK COMMUNICATION LINE (2)

DTC

Items
(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

U1000

CAN COMM CIRCUIT

When 4WAS front control unit is not transmitting or re-
ceiving 4WAS communication signal for 2 seconds or 
more.

4WAS communication 
line*/4WAS main control 
unit/4WAS front control 
unit error

U1002

SYSTEM COMM(CAN)

When 4WAS front control unit is not transmitting or re-
ceiving 4WAS communication signal for 2 seconds or 
less.

4WAS communication 
line*/4WAS main control 
unit/4WAS front control 
unit error

ABS actuator and electric 

unit (control unit)

Yaw rate/side G sensor.

Continuity

Connector

Terminal

Connector

Terminal

E41

25

M143

2

Existed

45

3