Mitsubishi Lancer Evolution X. Manual - part 164

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-121

• The valve relay in ASC-ECU is energized at all times, and 

the solenoid valve is always energized while the system is 
in operation unless the initial check is in progress when the 
ignition switch is turned ON, or unless the periodical system 
check is in progress.

• ASC-ECU activates the solenoid valve by turning on its driv-

ing transistor.

.

DTC SET CONDITIONS

These diagnostic trouble codes are set under the cases below.

• The solenoid valve is not energized even after ASC-ECU 

has turned on the driving transistor. (Open circuit is present 
in the power supply circuit to ASC-ECU solenoid valve or 
ASC-ECU solenoid valve circuit, or the valve relay has 
failed.)

• The solenoid valve still remains energized even after 

ASC-ECU has turned off the driving transistor. (Short circuit 
in the solenoid valve circuit.)

• When a solenoid valve failure is detected

.

PROBABLE CAUSES

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. 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: Are DTC C104B, C104F, C1053, C1057, C105F, C1063, 

C1067, C105B, C1200, C1204, C1208 or C120C set?
YES : Go to Step 3.
NO :  This diagnosis is complete.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-122

STEP 3. Check whether the DTC is reset.
Q: Are DTC C104B, C104F, C1053, C1057, C105F, C1063, 

C1067, C105B, C1200, C1204, C1208 or C120C set?
YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 4.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 4. Check whether the DTC is reset.
Q: Are DTC C104B, C104F, C1053, C1057, C105F, C1063, 

C1067, C105B, C1200, C1204, C1208 or C120C set?
YES : Return to Step 1.
NO :  This diagnosis is complete.

DTC C2104: Faulty valve power supply circuit

FUSIBLE
LINK

27

ASC-ECU

SOLENOID 
VALVE POWER 
SUPPLY

AC804600

Solenoid Valve Power Supply Circuit

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-123

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 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.

• The valve relay in ASC-ECU is energized at all times, and 

the solenoid valve is always energized while the system is 
in operation unless the initial check is in progress when the 
ignition switch is turned ON, or unless the periodical system 
check is in progress.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the solenoid valve 
supply voltage is out of the standard value.

.

PROBABLE CAUSES

Current trouble

• Fusible link malfunction
• Damaged wiring harness and connectors
• Abnormality in battery or generator
• ASC-ECU malfunction

Past trouble

• Carry out the diagnosis with a particular emphasis on the 

wiring harness and connector failures in the ASC-ECU sole-
noid valve power supply circuit (terminal No. 32) and in the 
ground circuit (terminal No. 16 and No. 47). For diagnosis 
procedures, refer to How to Treat Past Trouble (GROUP 00 
− How to Use Troubleshooting/Inspection Service Points 

P.00-16

).

AC708948

Connector: A-05

A-05 (B)

AB

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-124

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. 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 − 

CAN Bus Diagnostics table 

P.54C-9

). On completion, 

go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C2104 set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

STEP 3. Battery check
Refer to GROUP 54A − Battery Test 

P.54A-9

.

Q: Is the battery in good condition?

YES : Go to Step 4.
NO :  Replace the battery. Then go to Step 11.

STEP 4. 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 5.
NO :  Repair or replace the charging system component(s). 

Then go to Step 11.

STEP 5. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : Go to Step 6.
NO  :  Repair the defective connector. Then go to Step 11.

STEP 6. Fusible link check: Check the fusible link No.27.
Visually check for open circuit in the fusible link No.27.
Q: Is the check result normal?

YES : Go to Step 8.
NO :  Go to Step 7.