Mitsubishi Evolution X. Manual — part 806

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-231

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

.) Then go to Step 7.

STEP 2. Scan tool diagnostic trouble code
Using scan tool, check the diagnostic trouble code for ASC sys-
tem.
Q: Is any DTC set?

YES : Carry out the diagnosis for the DTC. (Refer to

P.35C-20

NO : Go to Step 3.

STEP 3. Check of ASC-ECU power supply circuit
Refer to

P.35C-243

Q: Is the check result normal?

YES : Go to Step 4.
NO : Carry out the diagnosis of ASC-ECU power supply

circuit system.(Refer to

P.35C-243

STEP 4. Scan tool diagnostic trouble code for other
systems
Using scan tool MB991958, check if diagnostic trouble code
No. U0141 is set by the combination meter system.
Q: Is the DTC set?

YES : Diagnose the combination meter. (Refer to GROUP

54A

− Combination Meter, Troubleshooting

P.54A-45

Then go to Step 7.

NO : Go to Step 5.

STEP 5. Scan tool diagnostic trouble code for other
systems
Using scan tool MB991958, check if diagnostic trouble code
No. U0121 is set by ETACS system.
Q: Is the DTC set?

YES : Diagnose the ETACS-ECU. (Refer to GROUP 54A

−

ETACS, Troubleshooting

P.54A-582

.) Then go to

Step 7.

NO : Go to Step 6.

STEP 6. Retest the system.
Q: Does the ABS warning light turn ON and OFF normally?

YES : Intermittent malfunction. (Refer to GROUP 00

− How

to Cope with Intermittent Malfunction

P.00-15

NO : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-272

.) Then go to Step 7.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-232

STEP 7. Retest the system.
Q: Does the ABS warning light turn ON and OFF normally?

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

Inspection Procedure 6: The ASC warning display stays ON even after the engine is started.

CAUTION

• 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

SYSTEM OPERATION

ASC-ECU sends the illumination request signal of ASC warn-
ing display to the combination meter through ETACS-ECU via
CAN communication.

TECHNICAL DESCRIPTION (COMMENT)

In the case of this trouble symptom, there may be a malfunction
to the CAN bus line, ETACS-ECU, combination meter, or
ASC-ECU.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• Malfunction of ETACS-ECU

• Combination meter malfunction

• ASC-ECU malfunction

• Control stop due to the low voltage

NOTE: Due to the abnormality in the supply voltage, the
diagnostic trouble code may not be set even when the ASC
warning display is illuminated.

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

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-233

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

.) Then go to Step 7.

STEP 2. Scan tool diagnostic trouble code
Using scan tool, check the diagnostic trouble code for ASC sys-
tem.
Q: Is any DTC set?

YES : Carry out the diagnosis for the DTC. (Refer to

P.35C-20

NO : Go to Step 3.

STEP 3. Check of ASC-ECU power supply circuit
Refer to

P.35C-243

Q: Is the check result normal?

YES : Go to Step 4.
NO : Carry out the diagnosis of ASC-ECU power supply

circuit system.(Refer to

P.35C-243

STEP 4. Scan tool diagnostic trouble code for other
systems
Using scan tool MB991958, check if diagnostic trouble code
No. U0141 is set by the combination meter system.
Q: Is the DTC set?

YES : Diagnose the combination meter. (Refer to GROUP

54A

− Combination Meter, Troubleshooting

P.54A-45

Then go to Step 7.

NO : Go to Step 5.

STEP 5. Scan tool diagnostic trouble code for other
systems
Using scan tool MB991958, check if diagnostic trouble code
No. U0121 is set by ETACS system.
Q: Is the DTC set?

YES : Diagnose the ETACS-ECU. (Refer to GROUP 54A

−

ETACS, Troubleshooting

P.54A-591

.) Then go to

Step 7.

NO : Go to Step 6.

STEP 6. Retest the system.
Q: Does the ASC warning display turn ON and OFF

normally?
YES : Intermittent malfunction. (Refer to GROUP 00

− How

to Cope with Intermittent Malfunction

P.00-15

NO : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-272

.) Then go to Step 7.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-234

STEP 7. Retest the system.
Q: Does the ASC warning display turn ON and OFF

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

Inspection Procedure 7: The ASC OFF display remains illuminated after the engine is started.

CAUTION

• 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

SYSTEM OPERATION

• ASC-ECU sends the illumination request signal of ASC

OFF display to the combination meter through ETACS-ECU
via CAN communication.

• By the operation of ASC OFF switch, the ASC OFF display

illuminates when the ASC function is stopped.

• When the ASC OFF switch is pressed shortly, the ASC sys-

tem is turned OFF.