Mitsubishi Evolution X. Manual - part 344

DIAGNOSIS <S-AWC(SUPER ALL WHEEL CONTROL)>

TSB Revision

MANUAL TRANSAXLE

22A-25

STEP 4. Scan tool diagnostic trouble code
Check if the wheel speed sensor-related, G and yaw rate sen-
sor-related, or steering wheel sensor-related diagnostic trouble 
code is set.
Q: Is the DTC set?

YES : Carry out the appropriate troubleshooting. Then go to 

Step 9.

NO :  Go to Step 5.

STEP 5. Check of steering wheel sensor installation status
Check that the steering wheel sensor is installed correctly. 
(Refer to GROUP 35C 

− Steering Wheel Sensor 

P.35C-279

.)

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Install the steering wheel sensor correctly. Then go to 

Step 6.

STEP 6. Wheel alignment check
Q: Is the check result normal?

YES : After checking the wheel alignment, calibrate the 

steering wheel sensor (refer to GROUP 35C 

− 

On-vehicle Service 

P.35C-267

,) and initialize 

AWC-ECU steering angle correction amount (refer to 

P.22A-113

.) Then, go to Step 7.

NO :  After adjusting the wheel alignment, calibrate the 

steering wheel sensor (refer to GROUP 35C 

− 

On-vehicle Service 

P.35C-267

,) and initialize 

AWC-ECU steering angle correction amount (refer to 

P.22A-113

.) Then, go to Step 7.

STEP 7. Scan tool service data
Item 11: Steering wheel sensor (refer to 

P.22A-107

.)

Q: Is the check result normal?

YES : Go to Step 8.
NO :  Replace the steering wheel sensor. (Refer to GROUP 

35C 

− Steering Wheel Sensor 

P.35C-279

.) Then, go to 

Step 9.

STEP 8. Check whether the DTC is reset.
Q: Is DTC No. C1219 set?

YES : Replace the AWC-ECU.(Refer to 

P.22A-132

.) Then, 

go to Step 9.

NO :  Intermittent malfunction. (Refer to GROUP 00 

− How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 9. Check whether the DTC is reset.
Q: Is DTC No. C1219 set?

YES : Return to Step 1.
NO :  This diagnosis is complete.

DIAGNOSIS <S-AWC(SUPER ALL WHEEL CONTROL)>

TSB Revision

MANUAL TRANSAXLE

22A-26

DTC C121A: Steering Wheel Sensor System (neutral learning abnormality)

CAUTION

• If there is any problem in the CAN bus lines, 

an incorrect diagnostic trouble code may be 
set. Prior to this diagnosis, diagnose the CAN 
bus lines.

• Whenever the ECU is replaced, ensure that 

the CAN bus lines are normal.

• When the steering wheel sensor is replaced, 

calibrate the steering wheel sensor (refer to 
GROUP 35C 

− On-vehicle Service 

P.35C-267

), 

and initialize the steering angle correction 
amount stored in AWC-ECU. (Item No.09: 
Steering angle correction amount initializa-
tion 

P.22A-113

.)

.

OPERATION

Steering wheel sensor stores the neutral position 
learned by the scan tool. When the neutral position 
has not been learned, the steering wheel sensor out-
puts the signal indicating that the learning has not 
been performed.

.

DTC SET CONDITIONS

This DTC is set when it is detected that the steering 
wheel sensor has not learned the neutral position.

.

PROBABLE CAUSES

• Steering wheel sensor neutral point not learned

• Malfunction of steering wheel sensor

• Malfunction of AWC ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?

YES : Go to Step 3.
NO :  Repair the CAN bus lines. (Refer to GROUP 54C 

− 

Troubleshooting 

P.54C-14

.) After repairing the CAN 

bus line, go to Step 2.

STEP 2. Check whether the DTC is reset.
Q: Is DTC No. C121A set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

STEP 3. Steering wheel sensor calibration
Perform calibration of the steering wheel sensor. (Refer to 
GROUP 35C 

− On-vehicle Service 

P.35C-267

.)

Q: Has the calibration succeeded?

YES : Go to Step 4.
NO :  Replace the steering wheel sensor. (Refer to GROUP 

35C 

− Steering Wheel Sensor 

P.35C-279

.) Then, go to 

Step 4.

STEP 4. Check whether the DTC is reset.
Q: Is DTC No. C121A set?

YES : Replace the AWC-ECU.(Refer to 

P.22A-132

.) Then, 

go to Step 5.

NO :  Intermittent malfunction. (Refer to GROUP 00 

− How 

to Cope with Intermittent Malfunction 

P.00-15

.)

DIAGNOSIS <S-AWC(SUPER ALL WHEEL CONTROL)>

TSB Revision

MANUAL TRANSAXLE

22A-27

STEP 5. Check whether the DTC is reset.
Q: Is DTC No. C121A set?

YES : Return to Step 1.
NO :  This diagnosis is complete.

DTC C123C: G and Yaw Rate Sensor (Faulty Signal)

CAUTION

• If there is any problem in the CAN bus lines, 

an incorrect diagnostic trouble code may be 
set. Prior to this diagnosis, diagnose the CAN 
bus lines.

• Whenever the ECU is replaced, ensure that 

the CAN bus lines are normal.

• When the steering wheel sensor is replaced, 

calibrate the steering wheel sensor (refer to 
GROUP 35C 

− On-vehicle Service 

P.35C-267

), 

and initialize the steering angle correction 
amount stored in AWC-ECU. (Item No.09: 
Steering angle correction amount initializa-
tion 

P.22A-113

.)

• Do not drop the G and yaw rate sensor or sub-

ject it to a shock.

• When G and yaw rate sensor is replaced, cali-

brate G and yaw rate sensor (refer to GROUP 
35C 

− On-vehicle Service 

P.35C-266

), and ini-

tialize the lateral/longitudinal acceleration 
correction amount stored in AWC-ECU. (Refer 
to item No.10: Lateral acceleration correction 
amount initialization, and No. 11: Longitudinal 
acceleration correction amount initialization 

P.22A-113

.)

.

OPERATION

The G and yaw rate sensor outputs the signal to 
ASC-ECU and AWC-ECU via the special CAN bus 
lines.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the abnor-
mality below is detected:

• Abnormality in G and yaw rate sensor output 

value

• This diagnostic trouble code is set when 

AWC-ECU determines that an abnormality is 
present by comparing the measurement values of 
G and yaw rate sensor with the calculation value 
of G and yaw rate calculated by the measure-
ment values of the wheel speed sensor and 
steering wheel sensor.

.

PROBABLE CAUSES

• Improper installation of G and yaw rate sensor

• Malfunction of G and yaw rate sensor

• Malfunction of wheel speed sensor

• Malfunction of steering wheel sensor

• Malfunction of AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?

YES : Go to Step 3.
NO :  Repair the CAN bus lines. (Refer to GROUP 54C 

− 

Troubleshooting 

P.54C-14

.) After repairing the CAN 

bus line, go to Step 2.

STEP 2. Check whether the DTC is reset.
Q: Is DTC No. C123C set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

DIAGNOSIS <S-AWC(SUPER ALL WHEEL CONTROL)>

TSB Revision

MANUAL TRANSAXLE

22A-28

STEP 3. Scan tool diagnostic trouble code
Q: Is DTC No. C2204 set?

YES : Perform the relevant troubleshooting.
NO :  Go to Step 4.

STEP 4. Scan tool diagnostic trouble code
Check if the local CAN communication-related, wheel speed 
sensor-related, or steering wheel sensor-related diagnostic 
trouble code is set.
Q: Is the DTC set?

YES : Perform the relevant troubleshooting.
NO :  Go to Step 5.

STEP 5. Check of G and yaw rate sensor installation status
Check that the G and yaw rate sensor is installed correctly. 
(Refer to GROUP 35C 

− G and Yaw Rate Sensor 

P.35C-278

.)

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Reinstall the G and yaw rate sensor correctly. Then 

go to Step 6.

STEP 6. Scan tool service data
Check the following service data. (Refer to 

P.22A-107

.)

• Item No. 26: Yaw rate sensor

• Item No. 29: Lateral G sensor

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Replace the G and yaw rate sensor. (Refer to 

GROUP 35C 

− G and Yaw Rate Sensor 

P.35C-278

.) 

Then go to Step 11.

STEP 7. Check of steering wheel sensor installation status
Check that the steering wheel sensor is installed correctly. 
(Refer to GROUP 35C 

− Steering Wheel Sensor 

P.35C-279

.)

Q: Is the check result normal?

YES : Go to Step 8.
NO :  Install the steering wheel sensor correctly. Then go to 

Step 8.