Mitsubishi Lancer Evolution X. Manual - part 178

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-177

STEP 5. Check whether the DTC is reset.
Q: Is DTC C1210 set?

YES : Replace the G and yaw rate sensor. (Refer to 

P.35C-304

.) Then go to Step 6.

NO :  The procedure is complete.

STEP 6. Check whether the DTC is reset.
Q: Is DTC C1210 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 7.

NO :  Intermittent malfunction. (Refer to GROUP 00 − How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 7. Check whether the DTC is reset.
Q: Is DTC C1210 set?

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

DTC C1242: Abnormality in G and yaw rate sensor (longitudinal G 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-287

.)

• 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-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

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 local CAN bus lines.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when an abnormality is 
detected by a comparison of the longitudinal G value output 
from G and yaw rate sensor with the wheel speed value output 
from wheel speed sensor.

.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-178

PROBABLE CAUSES

• Improper installation of the G and yaw rate sensor
• G and yaw rate sensor malfunction
• Wheel speed sensor malfunction
• ASC-ECU malfunction
• External noise interference

NOTE: This DTC may be set also when the vehicle is driven on 
the four-wheel drum tester.

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-15

.) 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-212

.) Then go to 

Step 3.

NO :  Go to Step 3.

STEP 3. Check whether the DTC is reset.
Q: Is DTC C1242 set?

YES : Go to Step 4.
NO :  This diagnosis is complete.

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

P.35C-22

.)

Q: Is any DTC set?

YES : Perform troubleshooting for the diagnostic trouble 

code that is set. (Refer to 

P.35C-22

.)

NO :  Go to Step 5.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-179

STEP 5. G and yaw rate sensor check
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-287

.) Then go to Step 6.

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

to 

P.35C-304

.) Then go to Step 8.

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

P.35C-276

.)

• Item 09: G sensor
• Item 96: G sensor offset

Q: Is the check result normal?

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

P.35C-304

.) Then go to Step 7.

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-298

.) 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.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-180

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-289

.)

• 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-287

.)

• 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-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

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 local 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.

• When abnormality is detected by comparing the value out-

put from the lateral G and yaw rate with the one from the 
steering wheel sensor and wheel speed 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