Infiniti G37 Coupe. Manual - part 1278

4WAS MAIN CONTROL UNIT

STC-163

< ECU DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

Fail Safe

INFOID:0000000001666485

4WAS system (Main)

• 4WAS system enters in the fail-safe mode (4WAS system stopped) and 4WAS warning lamp turns ON if an

error is detected in 4WAS system (4WAS main control unit) component part. 

• 4WAS system enters in the protection function mode (4WAS system temporarily stopped) if 4WAS system

continues the heavy load condition or the sensor self-check condition. (4WAS system reactivates automati-

JCGWA0054GB

STC-164

< ECU DIAGNOSIS >

[WITH 4WAS]

4WAS MAIN CONTROL UNIT

cally if the heavy load condition and the self-check condition are resolved.) 4WAS warning lamp stays OFF
in the protection function mode.

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

Mode

Warn-

ing 

lamp

DTC

Detected area (Error area)

Error area and root cause

Fail-safe

Turn-

ON

C1900
C1901
C1905
C1906
C1907
C1908
C1922
C1925
C1927
C1928
C1933

4WAS main control unit

4WAS main control unit error

Turn-

ON

C1902
C1903
C1904
C1910
C1913

4WAS rear motor

4WAS rear motor error

Turn-

ON

C1909

4WAS main control unit

4WAS main control unit

Turn-

ON

C1911

C1912

4WAS rear motor

4WAS rear motor power supply error

Turn-

ON

C1914

Rear wheel steering sensor

Rear wheel steering sensor power supply error

Turn-

ON

C1915
C1916

Rear wheel steering sensor

Rear wheel steering sensor output voltage error

Turn-

OFF

C1917

Rear wheel steering sensor

Rear wheel steering sensor (main and sub) output signal value error 
signal

Turn-

ON

C1918

Rear wheel steering sensor

Rear wheel steering sensor (main and sub) output signal error

Turn-

ON

C1919

ABS actuator and electric unit 
(control unit)

Vehicle speed signal error

Turn-

ON

C1920
C1923
C1924

Steering angle sensor

Steering angle sensor input signal error

Turn-

ON

C1921

ECM

Engine speed signal error

Turn-

ON

C1926

Steering angle sensor

Steering angle sensor error

Turn-

ON

C1930

4WAS front control unit

4WAS front control unit fail-safe mode

Turn-

ON

C1931

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

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

Turn-

ON

C1932

Steering angle sensor

Steering angle sensor input signal error

Turn-

ON

U1000

CAN communication line*

CAN communication error

Turn-

ON

U1010

CAN communication line*/
4WAS main control unit/ECM/
ABS actuator and electric unit 
(control unit)

CAN communication line/4WAS main control unit/ECM/ABS actua-
tor and electric unit (control unit) error

4WAS MAIN CONTROL UNIT

STC-165

< ECU DIAGNOSIS >

[WITH 4WAS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

EPS system

• EPS system (4WAS main control unit) enters the fail-safe mode

(that allows the steering force to be controlled without impairing the
drive ability) if the input from each sensor is not within the specified
range. Then, 4WAS warning lamp turns ON.

DTC Inspection Priority Chart

INFOID:0000000001666486

If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.

JSGIA0055GB

Mode

Warn-

ing 

lamp

DTC 

Detected area (Error area)

Error part and root cause

Fail-safe 

Turn-

ON

C1919

ABS actuator and electronic 
unit (control unit)

Vehicle speed signal error

Priority

Detected items (DTC)

1

• U1000 CAN COMM
• U1010 CONTROL UNIT (CAN)

2

• C1900 CONTROL UNIT [ABNORMAL1]
• C1901 CONTROL UNIT [ABNORMAL2]
• C1905 CONTROL UNIT [ABNORMAL3]
• C1906 CONTROL UNIT [ABNORMAL5]
• C1907 CONTROL UNIT [ABNORMAL4]
• C1908 CONTROL UNIT [ABNORMAL7]
• C1909 CONTROL UNIT [ABNORMAL6]
• C1922 CONTROL UNIT [ABNORMAL8]
• C1925 AD CONVERTER 
• C1927 CONTROL UNIT [ABNORMAL5]
• C1928 CONTROL UNIT [ABNORMAL9]
• C1933 CONTROL UNIT

3

• C1902 MOTOR OUTPUT [REV CURRENT]
• C1903 MOTOR OUTPUT [NO CURRENT]
• C1904 MOTOR OUTPUT [OVERCURRENT]
• C1910 MOTOR OUTPUT [MOTOR LOCK]
• C1911 MOTOR VOLTAGE [LOW VOLTEGE]
• C1912 MOTOR VOLTAGE [BAD OBSTRCT]
• C1913 MOTOR OUTPUT [ABNORML SIG]
• C1914 RR ST ANGLE SENSOR [ABNORML VOL]
• C1915 RR ST ANGLE SENSOR [MAIN SIGNAL]
• C1916 RR ST ANGLE SENSOR [SUB SIGNAL]
• C1917 RR ST ANGLE SENSOR [OFFSET SIG1]
• C1918 RR ST ANGLE SENSOR [OFFSET SIG2]

4

• C1919 VEHICLE SPEED SEN [NO SIGNAL]
• C1920 STEERING ANGLE SEN [NO SIGNAL]
• C1921 ENG REV SIGNAL
• C1923 STEERING ANGLE SEN [NO CHANGE]
• C1924 STEERING ANGLE SEN [NO NEUT STATE]
• C1926 STEERING ANGLE SEN
• C1932 STEERING ANGLE SEN

5

• C1930 4WAS FRONT ECU
• C1931 4WAS FRONT ECU COMM

STC-166

< ECU DIAGNOSIS >

[WITH 4WAS]

4WAS MAIN CONTROL UNIT

DTC Index

INFOID:0000000001666487

DTC

Items 

(CONSULT-III screen terms)

Reference

C1900

CONTROL UNIT
[ABNORMAL1]

STC-87, "DTC Logic"

C1901

CONTROL UNIT
[ABNORMAL2]

STC-87, "DTC Logic"

C1902

MOTOR OUTPUT
[REV CURRENT]

STC-89, "DTC Logic"

C1903

MOTOR OUTPUT
[NO CURRENT]

STC-89, "DTC Logic"

C1904

MOTOR OUTPUT
[OVERCURRENT]

STC-89, "DTC Logic"

C1905

CONTROL UNIT
[ABNORMAL3]

STC-92, "DTC Logic"

C1906

CONTROL UNIT
[ABNORMAL5]

STC-87, "DTC Logic"

C1907

CONTROL UNIT
[ABNORMAL4]

STC-87, "DTC Logic"

C1908

CONTROL UNIT
[ABNORMAL7]

STC-92, "DTC Logic"

C1909

CONTROL UNIT
[ABNORMAL6]

STC-94, "DTC Logic"

C1910

MOTOR OUTPUT
[MOTOR LOCK]

STC-89, "DTC Logic"

C1911

MOTOR VOLTAGE
[LOW VOLTEGE]

STC-96, "DTC Logic"

C1912

MOTOR VOLTAGE
[BAD OBSTRCT]

STC-96, "DTC Logic"

C1913

MOTOR OUTPUT
[ABNORML SIG]

STC-89, "DTC Logic"

C1914

RR ST ANGLE SENSOR
[ABNORML VOL]

STC-101, "DTC Logic"

C1915

RR ST ANGLE SENSOR
[MAIN SIGNAL]

STC-104, "DTC Logic"

C1916

RR ST ANGLE SENSOR
[SUB SIGNAL]

STC-104, "DTC Logic"

C1917

RR ST ANGLE SENSOR
[OFFSET SIG1]

STC-107, "DTC Logic"

C1918

RR ST ANGLE SENSOR
[OFFSET SIG2]

STC-107, "DTC Logic"

C1919

VEHICLE SPEED SEN
[NO SIGNAL]

STC-110, "DTC Logic"

C1920

STEERING ANGLE SEN
[NO SIGNAL]

STC-112, "DTC Logic"

C1921

ENG REV SIGNAL

STC-115, "DTC Logic"

C1922

CONTROL UNIT
[ABNORMAL8]

STC-92, "DTC Logic"

C1923

STEERING ANGLE SEN
[NO CHANGE]

STC-117, "DTC Logic"

C1924

STEERING ANGLE SEN
[NO NEUT STATE]

STC-120, "DTC Logic"