Infiniti G37 Coupe. Manual - part 1252

C1633 4WAS FRONT CONTROL UNIT

STC-59

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

3.

CHECK INFORMATION

• Check that any item below is applicable when malfunction occurs.
- Entering and exiting the garage (Frequent steering)
- When steering the steering wheel for a long time
Is the item applicable?

YES

>> 4WAS system protection function mode (overheat protection)(4WAS system temporary stop)

NO

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

Special Repair Requirement

INFOID:0000000001666327

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”.

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)"

.

Monitor item

Condition

Display value

THERM TEMP

Engine running (idling)

−

40 – 100

°

C

STC-60

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1651 IGNITION POWER SUPPLY

C1651 IGNITION POWER SUPPLY

Description

INFOID:0000000001666328

• 4WAS system function is controlled by transmitting the ignition switch signal to 4WAS front control unit.

DTC Logic

INFOID:0000000001666329

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 “C1651” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-60, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666330

1.

CHECK 4WAS FRONT CONTROL UNIT GROUND

1.

Turn the ignition switch OFF.

2.

Check the continuity between 4WAS front control unit harness connector and the ground.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace the harnesses and connectors.

2.

CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Check the voltage between 4WAS front control unit harness connectors.

Is the measurement value “9 V” or less?

YES

>>

Check the following items. Repair or replace the malfunctioning parts.

• 4WAS front control unit harness connector pin terminal and connection
• 10A fuse (#3) open
- Short among 10A fuse (#3) connector, 4WAS front control unit harness connector No. 15 termi-

nal and the ground

- Short among 10A fuse (#3) connector, unified meter and A/C amp No. 53 terminal and the

ground

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1651

IGN POWER SUPPLY

The ignition voltage signal error is detected.

4WAS front control unit or 
the ignition power supply 
error is detected.

4WAS front control unit

Continuity

Connector

Terminal

M42

18 – Ground

Existed

4WAS front control unit

Voltage (Approx.)

Connector

Terminal

M42

15 – 18

Battery voltage

C1651 IGNITION POWER SUPPLY

STC-61

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

• Open between the ignition switch and 4WAS front control unit harness connector No. 15 termi-

nal

• Ignition switch

NO

>> GO TO 3.

3.

CHECK 4WAS FRONT CONTROL UNIT SIGNAL

With CONSULT-III

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Check “IGN VOLT” item on “DATA MONITOR” of 4WAS front control unit.

Does the item on “DATA MONITOR” indicate “16 V” or more?

YES

>> Perform the symptom diagnosis for the charging system. Refer to 

STC-168, "Symptom Table"

.

NO

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

Special Repair Requirement

INFOID:0000000001666331

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”.

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)"

.

STC-62

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1652 4WAS FRONT MOTOR POWER SUPPLY

C1652 4WAS FRONT MOTOR POWER SUPPLY

Description

INFOID:0000000001666332

• The power supply for 4WAS front motor and 4WAS front control unit.

DTC Logic

INFOID:0000000001666333

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 “C1652” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-62, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666334

1.

4WAS FRONT MOTOR GROUND INSPECTION

1.

Turn the ignition switch OFF.

2.

Check the continuity between 4WAS front control unit harness connector and the ground.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace the harnesses and connectors.

2.

4WAS FRONT MOTOR POWER SUPPLY INSPECTION

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Check the voltage between 4WAS front control unit harness connectors.

Is the measurement value “9 V” or less?

YES

>>

Check the following items. Repair or replace the malfunctioning parts.

• 4WAS front control unit harness connector pin terminal and connection
• 40A fusible link (#I) open
- Short among 40A fusible link (#I) connector, 4WAS front control unit harness connector No. 11

terminal and the ground

• Open between the battery and 4WAS front control unit harness connector No. 11 terminal
• Battery

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1652

MOTOR POWER SUPPLY

4WAS front motor main power supply error is detected

4WAS front control unit or 
4WAS front motor power 
supply error is detected.

4WAS front control unit

Continuity

Connector

Terminal

M41

12 – Ground

Existed

4WAS front control unit

Voltage (Approx.)

Connector

Terminal

M41

11 – 12

Battery voltage