Infiniti G37 Coupe. Manual - part 1250

C1627 4WAS FRONT ACTUATOR

STC-51

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

YES

>> Replace 4WAS front actuator. Refer to 

STC-179, "Removal and Installation"

.

NO

>> GO TO 3.

3.

CHECK INFORMATION

With CONSULT-III

Check the “DATA MONITOR” value of each DTC detected with the self-diagnosis function. Refer to 

STC-142,

"Reference Value"

.

Is each data the standard value?

YES

>> Check each harness connector pin terminal for disconnection.

NO

>> Replace 4WAS front actuator. Refer to 

STC-179, "Removal and Installation"

.

Special Repair Requirement

INFOID:0000000001666314

AFTER REPLACING 4WAS FRONT ACTUATOR

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

STC-28, "4WAS

FRONT ACTUATOR NEUTRAL POSITION ADJUSTMENT : Special Repair Requirement (Pattern 2)"

.

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-52

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1628 4WAS FRONT ACTUATOR

C1628 4WAS FRONT ACTUATOR

Description

INFOID:0000000001666315

• Wiring connected to 4WAS front actuator is integrated with 4WAS front actuator.
• 4WAS front actuator rotates together with steering wheel.
• 4WAS front actuator mainly consists of five components. [4WAS front lock solenoid valve (lock structure),

front wheel steering angle sensor, 4WAS front motor, gear shaft, and spiral cable]

- 4WAS front lock solenoid valve (lock structure) is controlled by the 4WAS front control unit, and locks/

unlocks 4WAS front actuator.

- If a strong force (rotation direction) is applied to 4WAS front actuator, the locking mechanism (holder)

absorbs the force and locks 4WAS front actuator.

- Front wheel steering angle sensor detects a turning angle of 4WAS front motor.
- 4WAS front motor controls number of revolutions by a command value from the 4WAS front control unit.
- Gear shaft is an output axis of 4WAS front motor. (Gear shaft = 4WAS front motor revolution + steering

angle)

- Spiral cables mean the power line and signal lines of 4WAS front motor.

DTC Logic

INFOID:0000000001666316

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

RECHECK DTC

With CONSULT-III

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Steer 360

°

 leftward slowly. Then steer 360

°

 rightward to return the steering wheel to the straight-ahead

position. Repeat the same service for 1 minute or more.
NOTE:
The protection function mode (overheat protection) activates and the system stops if steering repeats for a
long time.

3.

Perform 4WAS front control unit self-diagnosis.

Is DTC “C1628” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-52, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666317

1.

CHECK FRONT WHEEL STEERING ANGLE SENSOR CIRCUIT (1)

1.

Turn the ignition switch OFF.

2.

Disconnect 4WAS front control unit harness connector.

3.

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.

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1628

ACTUATOR

The front wheel steering angle sensor error is detected.

Front wheel steering an-
gle sensor error

4WAS front control unit

Continuity

Connector

Terminal

M42

18 – Ground

Existed

C1628 4WAS FRONT ACTUATOR

STC-53

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

2.

CHECK FRONT WHEEL STEERING ANGLE SENSOR CIRCUIT (2)

1.

Connect 4WAS front control unit harness connector.

2.

Turn the ignition switch ON.

CAUTION:

Never start the engine.

3.

Check the continuity between 4WAS front actuator harness connector and 4WAS front control unit har-
ness connector.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

3.

CHECK FRONT WHEEL STEERING ANGLE SENSOR CIRCUIT (3)

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Steer to the straight-ahead position. Then turn the ignition switch OFF.

3.

Disconnect 4WAS front actuator harness connector.

4.

Apply 12 V current between 4WAS front actuator harness connector No. 10 terminal (positive) and NO. 3
terminal (negative). (Release the lock structure.)

CAUTION:

• Never make the terminals short.
• Connect the fuse between the terminals when applying the voltage.

5.

Slowly steer rightward and leftward alternately. Check the resistance between 4WAS front actuator har-
ness connectors.

CAUTION:

The steering angle must be within 10

°

 rightward and leftward.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Replace 4WAS front actuator. Refer to 

STC-179, "Removal and Installation"

.

4.

CHECK FRONT WHEEL STEERING ANGLE SENSOR SIGNAL

With CONSULT-III

1.

Connect 4WAS front actuator harness connector.

2.

Start the engine.

CAUTION:

Stop the vehicle.

3.

Rotate the steering wheel slowly. Check “MTR SEN U OUT”, “MTR SEN V OUT” and “MTR SEN W OUT”
item on “DATA MONITOR”of 4WAS front control unit.

Do all data monitor values indicate “Hi” or “Low” simultaneously?

YES

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

NO

>> Check 4WAS front actuator harness connector pin terminal for disconnection.

Component Inspection (Front Wheel Steering Angle Sensor)

INFOID:0000000001666318

1.

CHECK FRONT WHEEL STEERING ANGLE SENSOR

4WAS front actuator

4WAS front control unit

Continuity

Connector

Terminal

Connector

Terminal

M351

7

M42

18

Existed

4WAS front actuator

Resistance (Ap-

prox.)

Connector

Terminal

Connector

Terminal

M351

2

M351

7

1 k – 100 k

Ω

4

7

8

7

STC-54

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1628 4WAS FRONT ACTUATOR

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Steer to the straight-ahead position. Then turn the ignition switch OFF.

3.

Disconnect 4WAS front actuator harness connector.

4.

Apply 12 V current between 4WAS front actuator harness connector No. 10 terminal (positive) and NO. 3
terminal (negative). (Release the lock structure.)

CAUTION:

• Never make the terminals short.
• Connect the fuse between the terminals when applying the voltage.

5.

Slowly steer rightward and leftward alternately. Check the resistance between 4WAS front actuator har-
ness connectors.

CAUTION:

The steering angle must be within 10

°

 rightward and leftward.

6.

Connect 4WAS front actuator harness connector.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace 4WAS front actuator. Refer to 

STC-179, "Removal and Installation"

.

Special Repair Requirement

INFOID:0000000001666319

AFTER REPLACING 4WAS FRONT ACTUATOR

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

STC-28, "4WAS

FRONT ACTUATOR NEUTRAL POSITION ADJUSTMENT : Special Repair Requirement (Pattern 2)"

.

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)"

.

4WAS front actuator

Resistance (Ap-

prox.)

Connector

Terminal

Connector

Terminal

M351

2

M351

7

1 k – 100 k

Ω

4

7

8

7