Mitsubishi Evolution X. Manual — part 805

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-227

STEP 4. Coding data check
Using the scan tool, check if there is any abnormality to the
coding data stored in the ETACS-ECU. (Refer to GROUP 00

−

Coding Table

P.00-39

Q: Is the check result normal?

YES : Go to Step 5.
NO : Replace the ETACS-ECU. (Refer to GROUP 54A

−

ETACS-ECU

P.54A-676

.) Then go to Step 8.

STEP 5. 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 8.

NO : Go to Step 6.

STEP 6. 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 8.

NO : Go to Step 7.

STEP 7. 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 8.

STEP 8. Retest the system.
Q: Does the ABS warning light turn ON and OFF normally?

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

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-228

Inspection Procedure 4: The brake warning light does not illuminate when ignition switch is turned to
the ON position (engine stopped).

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

CIRCUIT OPERATION

• ASC-ECU sends the illumination request signal of the brake

warning light to the combination meter through
ETACS-ECU via CAN communication.

• When the ignition switch is turned ON, ASC-ECU illumi-

nates the brake warning light via ETACS-ECU for approxi-
mately 3 seconds for the purpose of bulb check.

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

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

.) Then go to Step 7.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-229

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. M.U.T.-III actuator test
Perform the following actuator tests from the combination
meter system to check if the brake warning light is illuminated.
(Refer to GROUP 54A

− Combination Meter, Actuator Test

Table

P.54A-82

• Item 07: Indicator1

Q: Is the check result normal?

YES : Go to Step 4.
NO : Carry out the diagnosis of the combination meter.

(Refer to GROUP 54A

− Combination Meter, Trouble

Symptom Chart

P.54A-59

.) Then go to Step 7.

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 brake 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-230

STEP 7. Retest the system.
Q: Does the brake warning light turn ON and OFF

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

Inspection Procedure 5: The ABS warning light remains illuminated even after the engine is started.

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

SYSTEM OPERATION

• ASC-ECU sends the illumination signal of ABS warning

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

• When the ignition switch is turned ON, ASC-ECU illumi-

nates the ABS warning light via ETACS-ECU for approxi-
mately 3 seconds for the purpose of bulb check.

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.