Mitsubishi Evolution X. Manual - part 791

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-171

STEP 7. Check whether the DTC is reset.
Q: Is DTC C1242 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-272

.) Then go to Step 8.

NO :  Intermittent malfunction. (Refer to GROUP 00 

− How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 8. Check whether the DTC is reset.
Q: Is DTC C1242 set?

YES : Return to Step 1.
NO :  The procedure is complete.

DTC C123C: Abnormality in G and yaw rate sensor (lateral G or yaw rate)

CAUTION

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

rect 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, always 

perform calibration to make ASC-ECU learn the neutral 
point. (Refer to 

P.35C-267

.)

• Do not drop the G and yaw rate sensor or subject it to a 

shock.

• When the G and yaw rate sensor is replaced, always 

perform the calibration to make ASC-ECU learn the 
neutral point. (Refer to 

P.35C-266

.)

• When the hydraulic unit (integrated with ASC-ECU) is 

replaced, always perform the calibration of steering 
wheel sensor, G and yaw rate sensor, brake fluid pres-
sure sensor, cut valve, and inlet valve.(Refer to 

P.35C-266

, 

P.35C-267

, 

P.35C-268

, and 

P.35C-269

.)

.

CIRCUIT OPERATION

• ASC-ECU supplies power to the G and yaw rate sensor at 

the terminal No. 1.

• The G and yaw rate sensor outputs the signal to ASC-ECU 

via the special CAN bus lines.

.

DTC SET CONDITIONS

This diagnostic trouble code is set if any malfunction below is 
found:

• Lateral G value or yaw rate value output from G and yaw 

rate sensor is abnormal.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-172

• This diagnostic trouble code is set when ASC-ECU deter-

mines that an abnormality is present by comparing the lat-
eral G value and yaw rate values output from G and yaw 
rate sensor with the wheel speed value output from wheel 
speed sensor, and with the steering wheel angle output 
from steering wheel sensor.

.

PROBABLE CAUSES

• Improper installation of the G and yaw rate sensor

• G and yaw rate sensor malfunction

• Steering wheel sensor malfunction

• Improper installation of steering wheel sensor

• Malfunction of wheel speed sensor

• ASC-ECU malfunction

• External noise interference

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827 M.U.T.-III USB Cable

• MB991910 M.U.T.-III Main Harness A

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

YES : Go to Step 2.
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 for diagnostic trouble codes of other 
systems
Check if diagnostic trouble code No. U0125 is also set in 
ASC-ECU.
Q: Is DTC U0125 set?

YES : Perform troubleshooting for the diagnostic trouble 

code that is set. (Refer to 

P.35C-202

.) Then go to 

Step 3.

NO :  Go to Step 3.

STEP 3. Check whether the DTC is reset.
Q: Is DTC C123C set?

YES : Go to Step 4.
NO :  The procedure is complete.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-173

STEP 4. Check of wheel speed sensor-related diagnostic 
trouble code
Using scan tool MB991958, check if the wheel speed sen-
sor-related or steering wheel sensor-related diagnostic trouble 
code is set. (Refer to 

P.35C-20

.)

Q: Is any DTC set?

YES : Perform troubleshooting for the diagnostic trouble 

code that is set. (Refer to 

P.35C-20

.)

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.
Q: Is the check result normal?

YES : After checking the G and yaw rate sensor, perform 

the calibration of the G and yaw rate sensor to make 
ASC-ECU relearn the neutral point.(Refer to 

P.35C-266

.) Then go to Step 6.

NO :  Reinstall the G and yaw rate sensor correctly. (Refer 

to 

P.35C-278

.) Then go to Step 10.

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

P.35C-255

.)

• Item 08: Lateral G-sensor

• Item 12: Yaw rate sensor

Q: Is the check result normal?

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

P.35C-278

.) Then go to Step 10.

STEP 7. Check of steering wheel sensor installation status
Check that the steering wheel sensor is installed correctly.
Q: Is the check result normal?

YES : Go to Step 8.
NO :  Install the steering wheel sensor correctly. (Refer to 

P.35C-279

.) Then go to Step 8.

STEP 8. Wheel alignment check
Refer to 

P.33-7

.

Q: Is the check result normal?

YES : After checking the wheel alignment, perform the 

calibration of steering wheel sensor to make 
ASC-ECU relearn the neutral point.(Refer to 

P.35C-267

.) Then go to Step 9.

NO :  After adjusting the wheel alignment, perform the 

calibration of steering wheel sensor to make 
ASC-ECU relearn the neutral point.(Refer to 

P.35C-267

.) Then go to Step 9.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-174

STEP 9. Scan tool service data
Check the following service data. (Refer to 

P.35C-255

.)

• Item 11: Steering angle sensor

Q: Is the check result normal?

YES : Go to Step 10.
NO :  Replace the steering wheel sensor. (Refer to 

P.35C-279

.) Then go to Step 10.

STEP 10. Check whether the DTC is reset.
Q: Is DTC C123C set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-272

.) Then go to Step 11.

NO :  Intermittent malfunction. (Refer to GROUP 00 

− How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 11. Check whether the DTC is reset.
Q: Is DTC C123C set?

YES : Return to Step 1.
NO :  The procedure is complete.

DTC C2204: Internal abnormality in G and yaw rate sensor

CAUTION

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

rect 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.

• Do not drop the G and yaw rate sensor or subject it to a 

shock.

• When the G and yaw rate sensor is replaced, always 

perform the calibration to make ASC-ECU learn the 
neutral point. (Refer to 

P.35C-266

.)

• When the hydraulic unit (integrated with ASC-ECU) is 

replaced, always perform the calibration of steering 
wheel sensor, G and yaw rate sensor, brake fluid pres-
sure sensor, cut valve, and inlet valve.(Refer to 

P.35C-266

, 

P.35C-267

, 

P.35C-268

, and 

P.35C-269

.)

.

CIRCUIT OPERATION

• ASC-ECU supplies power to the G and yaw rate sensor at 

the terminal No. 1.

• The G and yaw rate sensor outputs the signal to ASC-ECU 

via the special CAN bus lines.

.

DTC SET CONDITIONS

This diagnostic trouble code is set if any malfunction below is 
found: