Mitsubishi Evolution X. Manual — part 777

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-115

STEP 13. Check of wheel speed sensor installation status
Check the installation status of wheel speed sensor <RR> (dis-
connection of wheel speed sensor, looseness of mounting bolt,
etc.).
Q: Is the check result normal?

YES : Go to Step 14.
NO : Reinstall the wheel speed sensor <RR> correctly.

(Refer to

P.35C-274

.) Then go to Step 17.

STEP 14. Wheel bearing looseness check
NOTE: Wheel bearing looseness may increase the gap
between the wheel speed sensor and the wheel speed detec-
tion magnet encoder. Check the wheel bearing <RR> for loose-
ness. (Refer to GROUP 27

−

On-vehicle Service

P.27-33

Q: Is the check result normal?

YES : Go to Step 15.
NO : Replace the rear wheel hub assembly. (Refer to

GROUP 27

− Rear Axle Hub Assembly

P.27-36

STEP 15. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or defor-
mation.
Q: Is the check result normal?

YES : Go to Step 16.
NO (Adhesion of foreign materials) : Clean the encoder

so as not to disturb the magnetization pattern on the
encoder while taking care of the magnet, magnetic
substance, and magnetic attraction.

NO (Deformation) : Replace the rear hub assembly. (Refer

to GROUP 27

− Rear Axle Hub Assembly

P.27-36

STEP 16. Check whether the DTC is reset.
Drive the vehicle at 12mph (20 km/h) or more.
NOTE: The ABS warning light does not turn OFF in some
cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1049 set?

YES : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-272

.) Then go to Step 17.

NO : Intermittent malfunction. (Refer to GROUP 00

− How

to Cope with Intermittent Malfunction

P.00-15

STEP 17. Check whether the DTC is reset.
Drive the vehicle at 12mph (20 km/h) or more.
NOTE: The ABS warning light does not turn OFF in some
cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1049 set?

YES : Return to Step 1.
NO : This diagnosis is complete.

AC608248AB

Magnetic
encoder

Rear Wheel
bearing

Rear wheel
hub
assembly

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-116

DTC C104B: Abnormality in FL wheel inlet valve system

DTC C104F: Abnormality in FR wheel inlet valve system

DTC C1053: Abnormality in RL wheel inlet valve system

DTC C1057: Abnormality in RR wheel inlet valve system

DTC C105F: Abnormality in FL wheel outlet valve system

DTC C1063: Abnormality in FR wheel outlet valve system

DTC C1067: Abnormality in RL wheel outlet valve system

DTC C105B: Abnormality in RR wheel outlet valve system

DTC C1200: Abnormality in FL/RR wheel cut valve system

DTC C1204: Abnormality in FR/RL wheel cut valve system

DTC C1208: Abnormality in FL/RR wheel suction valve system

DTC C120C: Abnormality in FR/RL wheel suction valve system

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

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.

• 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

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-117

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-14

.) 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.

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-272

.) 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.

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-118

DTC C2104: Faulty valve power supply circuit

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

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

DTC SET CONDITIONS

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

PROBABLE CAUSES