Mitsubishi Evolution X. Manual — part 786

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-151

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-266

,

P.35C-267

,

P.35C-268

, and

P.35C-269

.)

.

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.

• 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.

• 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 ASC-ECU power
supply voltage and solenoid valve power supply voltage
become 18.0

± 1.0 V or higher.

.

PROBABLE CAUSES

• Battery failure

• Battery terminal looseness

• Fusible link malfunction

• Damaged wiring harness and connectors

• ASC-ECU malfunction

• Charging system failed

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

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-152

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-14

.) After repairing the CAN

bus line, go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C2101 set?

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

STEP 3. Battery terminal check
Check that the battery terminal is not loose.
Q: Is the check result normal?

YES : Go to Step 4.
NO : Securely install the battery terminal. Then go to Step

4.

STEP 4. Battery check
Refer to GROUP 54A

− Battery Test

P.54A-9

.

Q: Is the battery in good condition?

YES : Go to Step 6.
NO : Charge or replace the battery, and then go to Step 5.

STEP 5. Charging system check
Refer to GROUP 16

− Charging System

P.16-7

.

Q: Is the charging system in good condition?

YES : Go to Step 6.
NO : Repair or replace the charging system component(s).

STEP 6. Fusible link check: Check the fusible link No.27
and No.34.
Check that the fusible link No. 27 and No. 34 are normal and
does not exceed the capacity.
Q: Is the check result normal?

YES : Go to Step 7.
NO : Replace the fusible link No.27 or No.34.

STEP 7. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : Go to Step 8.
NO : Repair the defective connector.

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-153

STEP 8. Voltage measurement at the A-05 ASC-ECU
connector
(1) Disconnect the connector, connect the ASC check harness

(Special tool: MB991997) to the wiring harness-side
connector, and measure the voltage at the special tool
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Measure the voltage between the terminal No. 32 and the

body ground.

OK: System voltage

Q: Is the check result normal?

YES : Go to Step 9.
NO : Repair the wiring harness between A-05 ASC-ECU

connector terminal No. 32 and the fusible link No. 27.

STEP 9. Check of fuse No. 17
Check that the fuse No. 17 is normal and does not exceed the
capacity.
Q: Is the check result normal?

YES : Go to Step 10.
NO : Replace the fuse No. 17.

STEP 10. Connector check: C-309 ETACS-ECU connector
and C-315 ETACS-ECU connector
Q: Is the check result normal?

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

STEP 11. Voltage measurement at the C-309 ETACS-ECU
connector
(1) Disconnect the connector, and measure at the wiring

harness-side connector.

(2) Measure the voltage between the terminal No. 1 and the

body ground.

OK: System voltage

Q: Is the check result normal?

YES : Go to Step 12.
NO : Repair the wiring harness between C-309

ETACS-ECU connector terminal No. 1 and the fusible
link No. 34.

AC400817CN

ASC-ECU

MB991997

A-05 ASC-ECU
harness connector

Check harness

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-154

STEP 12. Voltage measurement at the C-315 ETACS-ECU
connector
(1) Without disconnecting the connector, measure by

backprobing.

(2) Measure the voltage between the terminal No. 4 and the

body ground.

OK: System voltage

Q: Is the check result normal?

YES : Go to Step 13.
NO : Replace the ETACS-ECU. (Refer to GROUP 54A

−

ETACS-ECU

P.54A-676

.) Then go to Step 17.

STEP 13. Connector check: C-103 joint connector, C-130
intermediate connector
Q: Is the check result normal?

YES : Go to Step 14.
NO : Repair the defective connector.

STEP 14. Voltage measurement at the A-05 ASC-ECU
connector
(1) Disconnect the connector, connect the ABS check harness

(Special tool: MB991997) to the wiring harness-side
connector, and measure the voltage at the special tool
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Measure the voltage between the terminal No. 2 and the

body ground.

OK: System voltage

Q: Is the check result normal?

YES : Go to Step 15.
NO : Repair the wiring harness between C-315

ETACS-ECU connector terminal No. 4 and A-05
ASC-ECU connector terminal No. 2.

AC400817CN

ASC-ECU

MB991997

A-05 ASC-ECU
harness connector

Check harness