Infiniti G37 Coupe. Manual - part 1251

C1631, C1632 4WAS FRONT CONTROL UNIT

STC-55

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

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STC

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C1631, C1632 4WAS FRONT CONTROL UNIT

Description

INFOID:0000000001666320

• Each sensor signal controls 4WAS front actuator.
• The fail-safe functions stops the rear wheel angle function (the front wheel is the steering wheel cutting

angle) when the electric components and the mechanical components are malfunctioning.

• The protection function mode stops 4WAS system intermittently when 4WAS system continues high loaded

condition and overheat condition or the input signal does not transmit to 4WAS front control unit.

• 4WAS front control unit and 4WAS main control unit control the 4WAS system by 4WAS communication line

to optimize control.

DTC Logic

INFOID:0000000001666321

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 “C1631” or “C1632” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-55, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666322

1.

CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY

1.

Turn the ignition switch OFF.

2.

Disconnect 4WAS front control unit harness connector.

3.

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

4.

Turn the ignition switch ON.

CAUTION:

Never start the engine.

5.

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

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1631

CONTROL UNIT

An error is detected inside 4WAS front control unit.

4WAS front control unit or 
4WAS front control unit 
power supply error is de-
tected.

C1632

CONTROL UNIT

An error is detected inside 4WAS front control unit.

4WAS front control unit or 
4WAS front control unit 
power supply error is de-
tected.

4WAS front control unit

Voltage (Approx.)

Connector

Terminal

M41

11 – Ground

Battery voltage

M42

15 – Ground

0 V

STC-56

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1631, C1632 4WAS FRONT CONTROL UNIT

Is the inspection result normal?

YES

>> GO TO 2.

NO

>>

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

• 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
• 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 harness connector No. 53

terminal and the ground

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

nal

• Battery or ignition switch

2.

CHECK 4WAS FRONT CONTROL UNIT GROUND

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

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace the harnesses and connectors.

3.

CHECK TERMINAL

Check 4WAS front control unit harness connector pin terminal and connection for disconnection.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair or replace the specific malfunctioning part.

4.

CHECK INFORMATION

• Check that any item below is applicable when the malfunctions occur.
- The engine stall occurs while driving or stopping the vehicle.
- When detecting the charging system error
Is the item applicable?

YES

>>

Check the error system.

• Perform ECM symptom diagnosis. Refer to 

EC-589, "Symptom Table"

.

• 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:0000000001666323

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.

4WAS front control unit

Voltage (Approx.)

Connector

Terminal

M41

11 – Ground

Battery voltage

M42

15 – Ground

4WAS front control unit

Continuity

Connector

Terminal

M41

12 – Ground

Existed

M42

18 – Ground

34 – Ground

C1631, C1632 4WAS FRONT CONTROL UNIT

STC-57

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C

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• 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-58

< COMPONENT DIAGNOSIS >

[WITH 4WAS]

C1633 4WAS FRONT CONTROL UNIT

C1633 4WAS FRONT CONTROL UNIT

Description

INFOID:0000000001666324

• Each sensor signal controls 4WAS front actuator.
• The fail-safe functions stops the rear wheel angle function (the front wheel is the steering wheel cutting

angle) when the electric components and the mechanical components are malfunctioning.

• The protection function stops 4WAS system temporarily when: 
- 4WAS system continues being high load/overheat condition.
- The input signal is not transmitted to 4WAS front control unit.
• 4WAS front control unit and 4WAS main control unit control the 4WAS system by 4WAS communication line

to optimize control.

DTC Logic

INFOID:0000000001666325

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 “C1633” detected?

YES

>> Proceed to diagnosis procedure. Refer to 

STC-58, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001666326

1.

CHECK 4WAS FRONT CONTROL UNIT (1)

With CONSULT-III

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Check “THERM TEMP” on DATA MONITOR of 4WAS front control unit.

3.

Steer the steering wheel 360

°

 leftward slowly and then steer 360

°

 rightward. Return the steering wheel to

the straight-ahead position. Repeat the same service for 3 minutes.

4.

Check “THERM TEMP” on DATA MONITOR of 4WAS front control unit.

Is DATA MONITOR value difference between before and after the service 3

°

 or less?

YES

>> Replace 4WAS front control unit. Refer to 

STC-177, "Exploded View"

.

NO

>> GO TO 2.

2.

CHECK 4WAS FRONT CONTROL UNIT (2)

With CONSULT-III

1.

Start the engine.

CAUTION:

Stop the vehicle.

2.

Check “THERM TEMP” item on “DATA MONITOR” of 4WAS front control unit.

3.

Steer the steering wheel 360

°

 leftward slowly and then steer 360

°

 rightward. Return the steering wheel to

the straight-ahead position. Repeat the same service for 3 minutes.

4.

Check “THERM TEMP” item on “DATA MONITOR” of 4WAS front control unit.

DTC

Items

(CONSULT-III screen terms)

Diagnostic item is detected when...

Possible cause

C1633

CONTROL UNIT

An error is detected inside 4WAS front control unit.

4WAS front control unit 
error