Mitsubishi Lancer Evolution X. Manual - part 198

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-257

PROBABLE CAUSES

• Low battery output
• Wiring harness or connector failure of CAN bus line
• ASC-ECU malfunction
• Different ETACS-ECU, abnormal variant coding information
• Abnormal engine coding data

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. Check the DTC.
Using scan tool, check the diagnostic trouble code for ASC sys-
tem. (Refer to 

P.35C-22

.)

Q: Is the check result normal?

YES : Go to Step 2.
NO :  Carry out the diagnosis for the DTC. (Refer to 

P.35C-22

.)

STEP 2. Engine control module coding data check
Using the scan tool, check if there is any abnormality to the fol-
lowing coding data stored in the engine control module. (Refer 
to GROUP 00 − Coding Table 

P.00-26

.)

A.S.C.

OK: Present

Q: Is the check result normal?

YES : Go to Step 3.
NO :  Replace the engine control module. (Refer to GROUP 

13A − Engine Control Module 

P.13A-888

.) Then go to 

Step 4.

STEP 3. Hydraulic unit (integrated with ASC-ECU) check
Check that the brake tube is correctly mounted to the hydraulic 
unit (integrated with ASC-ECU). (Refer to 

P.54A-646

.)

Q: Is the check result normal?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-284

.) Then go to Step 4.

NO :  Connect the brake tubes correctly, and repair or 

replace the external brake lines of the hydraulic unit 
(integrated with ASC-ECU).

STEP 4. Operation check
Q: Does the skid control/TCL operate normally?

YES : The procedure is complete.
NO :  Check the brake related components other than the 

skid control/TCL.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-258

Inspection Procedure 11: ASC-ECU power supply circuit system

ASC-ECU Power Supply Circuit

FUSIBLE 
LINK

27

FUSIBLE 
LINK

26

FUSIBLE 
LINK

34

SOLENOID 
VALVE 
POWER 
SUPPLY

MOTOR 
POWER 
SUPPLY

ETACS-
ECU

AWC-ECU

AC902081

ASC-ECU

JOINT 
CONNECTOR 
(3)

JOINT 
CONNECTOR 
(4)

POWER 
SUPPLY

POWER 
SUPPLY

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-259

CAUTION

• When the ASC-ECU power supply voltage becomes 9.7 

± 0.3 V or less, the ABS warning light, ASC warning dis-

play, and ASC OFF display illuminate, and the ABS, sta-
bility control, and TCL controls are prohibited.

• If the battery terminal is not tightened properly, a dump 

surge may occur and the power supply voltage may 
become abnormally high for a short period of time.

• 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

.)

.

SYSTEM OPERATION

• ASC-ECU contains the power supply circuit (terminal No. 

32) for the solenoid valve. The solenoid valve is energized 
by the valve relay, which is incorporated in ASC-ECU.

• ASC-ECU contains the power supply circuit (terminal No. 1) 

for the pump motor. The pump motor is energized by the 
motor relay, which is incorporated in ASC-ECU.

• ASC-ECU contains the power supply circuit (terminal No. 2) 

for ASC-ECU, and the power is supplied from the fusible 
link No. 34 through the multi-purpose fuse No. 17.

• If a malfunction occurs in the ASC-ECU power supply, the 

communication with scan tool becomes unavailable.

AC708948

Connector: A-05

A-05 (B)

AB

AC708972AS

Connectors: C-309, C-315, C-317

ETACS-ECU

C-315

C-317

C-309 (B)

AC708950

Connectors: C-103, 130

AJ

C-103 (B)

C-130 (BR)

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-260

.

PROBABLE CAUSES

• Damaged wiring harness and connectors
• Malfunction of fuse or fusible link
• Improper tightening of battery terminal
• Improper tightening of grounding bolt
• Battery failure
• Charging system failed
• 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

• MB991997: ASC check harness

STEP 1. Battery check
Refer to GROUP 54A − Battery Test 

P.54A-9

.

Q: Is the battery in good condition?

YES : Go to Step 3.
NO :  Charge or replace the battery. Then, go to Step 2.

STEP 2. Charging system check
Refer to GROUP 16 − Output Current Test 

P.16-8

.

Q: Is the charging system in good condition?

YES : Go to Step 3.
NO :  Repair or replace the charging system component(s).

STEP 3. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : Go to Step 4.
NO  :  Repair the defective connector.