Mitsubishi Lancer Evolution X. Manual - part 175

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-165

STEP 15. Check whether the DTC is reset.
Q: Is DTC C2101 set?

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

DTC C1395: Brake fluid filling not completed

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 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

.)

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the brake fluid is not 
filled in the hydraulic unit.

.

PROBABLE CAUSES

• Different hydraulic unit (For delivery to factory)
• ASC-ECU malfunction

DIAGNOSIS

Required Special Tools:

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

• MB991824: 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. DTC recheck after repairing the CAN bus line
Q: Is DTC C1395 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.)

NO :  The procedure is complete.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-166

DTC C121C: Torque request signal rejection

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 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 sends the signal to the engine control module as 
necessary to decrease the engine output for ASC system oper-
ation.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the output decrease 
request is rejected by the engine control module.

.

PROBABLE CAUSES

• Wrong coding
• Engine ECU malfunction
• 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 3.
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. DTC recheck after repairing the CAN bus line
Q: Is DTC C121C set?

YES : Go to Step 3.
NO :  The procedure is complete.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-167

STEP 3. M.U.T.-III other system diagnostic trouble code
Using scan tool MB991958, check if a diagnostic trouble code 
is set in the engine control module. (Refer to GROUP 13A − 

Troubleshooting 

P.13A-48

.)

Q: Is any DTC set?

YES : Troubleshoot the diagnostic trouble code of engine 

control module. (Refer to GROUP 13A − 

Troubleshooting 

P.13A-48

.)

NO :  Go to Step 4.

STEP 4. Scan tool service data
Check the following service data. (Refer to 

P.35C-276

.)

• Item 68: Allow ESP torque request

Q: Is the check result normal?

YES : Go to Step 5.
NO :  Replace the engine control module. (Refer to GROUP 

13A − Engine Control Module 

P.13A-888

.) Then go to 

Step 5.

STEP 5. Check whether the DTC is reset.
Q: Is DTC C121C set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 6.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 6. Check whether the DTC is reset.
Q: Is DTC C121C set?

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

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-168

DTC C1290: CAN time-out error

CAUTION

• If diagnostic trouble code No. C1290 is set in ASC-ECU, 

always diagnose the CAN bus lines. If there is any fault 
in the CAN bus lines, an incorrect DTC may be set.

• When the diagnostic trouble code No. C1290 is set in 

ASC-ECU, a diagnostic trouble code for another system 
may also be set. When the diagnostic trouble code for 
another system is set, carry out diagnosis for that sys-
tem first.

• Whenever the ECU is replaced, ensure that the commu-

nication circuit is normal.

• When the steering wheel sensor is replaced, always 

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

P.35C-289

.)

• 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 receives signals necessary for the operations of 
ABS, stability control, and TCL from the engine control module, 
transaxle assembly (with built-in ECU) <TC-SST>, 
S-AWC-ECU, ETACS-ECU, and the steering wheel sensor via 
the CAN bus lines.

.

DTC SET CONDITIONS

This diagnostic trouble code is stored if ASC-ECU cannot 
receive signals necessary for the operations of ABS, stability 
control, and TCL from the engine control module, transaxle 
assembly (with built-in ECU) <TC-SST>, S-AWC-ECU, 
ETACS-ECU, and the steering wheel sensor.

.

PROBABLE CAUSES

• ECM malfunction
• Malfunction of transaxle assembly <TC-SST>
• S-AWC-ECU malfunction
• ETACS-ECU malfunction
• Steering wheel sensor malfunction
• Malfunction of the CAN bus
• ASC-ECU malfunction
• Interchanging of ETACS-ECU with another vehicle