Infiniti G35 (V35) Sedan. Manual - part 1289

STC-46

< FUNCTION DIAGNOSIS >

[WITH 4WAS]

DIAGNOSIS SYSTEM (4WAS MAIN CONTROL UNIT)

• The communication status and the number of errors of 4WAS main control unit, ECM, ABS actuator and

electric unit (control unit), 4WAS front control unit and the steering angle sensor are indicated.

• Error counter displays OK if any malfunction is not detected in the past. If the malfunction is detected, it dis-

plays 0. When turning the ignition switch ON, if it is normal, it displays 1. The upper limit of the counter is 39.

ACTIVE TEST MODE

Description

• 4WAS rear actuator assembly activation is checked according to the control signal from CONSULT-III.
• The control signal forcibly activates (ON/OFF) 4WAS rear assembly, performs the self-diagnosis and checks

each sensor in “SELF DIAGNOSTIC MODE”.

CAUTION:

Perform the active test while the vehicle is stopped.

Standard value

Item

PRSNT

PAST

TRANSMIT DIAG

OK / UNKWN

OK / 0 – 39 

ECM

OK / UNKWN

OK / 0 – 39 

VDC/TCS/ABS

OK / UNKWN

OK / 0 – 39 

STRG

OK / UNKWN

OK / 0 – 39 

4WAS

OK / UNKWN

OK / 0 – 39 

Select test item

Control signal

Remarks

SELF DIAGNOSTIC MODE

ON

CAUTION:

Perform the active test while the vehicle 
is stopped.

4WAS rear actuator assembly activates. It 
activates in the same direction as the steer-
ing angle by inputting the steering angle.

OFF

4WAS rear actuator assembly stops the ac-
tivation.

Monitor item

Active test “ON”

STEERING ANG

0

°

 (Neutral)

R 90

°

L 90

°

RR ST ANG-MAI

2.4 V

Approx. 4.4 V

Approx. 0.4 V

RR ST ANG-SUB

2.4 V

Approx. 4.4 V

Approx. 0.4 V

MOTOR CURRENT

No output (Approx. 0 A)

Output (change)

C1621, C1622 4WAS FRONT ACTUATOR

STC-47

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

COMPONENT DIAGNOSIS

C1621, C1622 4WAS FRONT ACTUATOR

Description

INFOID:0000000000958744

• 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:0000000000958745

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

RECHECK DTC

 With CONSULT-III

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Steer to 360

°

 leftward slowly. Then steer to 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 “C1621” or “C1622” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-47, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000000958746

1.

CHECK 4WAS FRONT MOTOR CIRCUIT

1.

Turn the ignition switch OFF.

2.

Disconnect 4WAS front actuator harness connector.

3.

Check the resistance between 4WAS front actuator harness connectors.

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1621

ACTUATOR

4WAS front motor current valve error is detected.
(4WAS front motor current valve is excessively large.)

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

C1622

ACTUATOR

4WAS front motor voltage valve or current error valve is 
detected.
(4WAS front motor voltage valve error is detected.)
(Voltage valve or current valve error is detected when 
starting the system.)

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

STC-48

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1621, C1622 4WAS FRONT ACTUATOR

4.

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

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Replace 4WAS front actuator. Refer to 

ST-21, "WITH 4WAS : Exploded View"

.

2.

PERFORM SELF-DIAGNOSIS (4WAS FRONT CONTROL UNIT)

 With CONSULT-III

1.

Connect 4WAS front control unit harness connector.

2.

Perform 4WAS front control unit self-diagnosis.

Is DTC “C1621” or “C1622” detected?

YES

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

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 control unit. Refer to 

STC-177, "Exploded View"

.

Component Inspection (4WAS Front Motor)

INFOID:0000000000958747

1.

CHECK 4WAS FRONT MOTOR

1.

Turn the ignition switch OFF.

2.

Disconnect 4WAS front actuator harness connector.

3.

Check the resistance between 4WAS front actuator harness connectors.

4.

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

4WAS front actuator

Resistance 

(Approx.)

Connector

Terminal

Connector

Terminal

M351

1

M351

5

0.1 – 1 

Ω

1

6

5

6

4WAS front actuator

Continuity

Connector

Terminal

M351

1 – Ground

Not existed

5 – Ground

6 – Ground

4WAS front actuator

Resistance 

(Approx.)

Connector

Terminal

Connector

Terminal

M351

1

M351

5

0.1 – 1 

Ω

1

6

5

6

C1621, C1622 4WAS FRONT ACTUATOR

STC-49

< 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

>> INSPECTION END

NO

>> Replace 4WAS front actuator. Refer to 

ST-21, "WITH 4WAS : Exploded View"

.

Special Repair Requirement

INFOID:0000000000958748

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:

• Replace it without erasing 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” when erasing the memory of the self-diagnosis results (record).

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

Continuity

Connector

Terminal

M351

1 – Ground

Not existed

5 – Ground

6 – Ground