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Mitsubishi Evolution X. Manual - part 811

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-251

Inspection Procedure 12: ABS/skid control/TCL operates too frequently.

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.

COMMENTS ON TROUBLE SYMPTOM

• Although it is difficult to determine the trouble cause since it

depends on the running status and road surface condition,
a malfunction of hydraulic circuit may be present if no diag-
nostic trouble code is detected.

• If a wheel or tire of other than the genuine specified size is

mounted, the ABS/skid control/TCL may be activated pre-
maturely.

• If non-genuine braking device or non-genuine impact reduc-

ing device is mounted, the ABS/skid control/TCL may be
activated prematurely.

PROBABLE CAUSES

• Installation of wheel or tire other than genuine specified size

• Tire pressure abnormality

• Tire wear and deterioration

• Installation of non-genuine braking device or non-genuine

impact reducing device

• Wheel alignment abnormality

• Malfunction of brake-related components

• Malfunction of wheel speed sensor

• Malfunction of G and yaw rate sensor

• Malfunction of steering wheel sensor

• Malfunction of hydraulic unit (integrated with ASC-ECU)

• Malfunction of hydraulic circuit

• External noise interference

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

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-252

STEP 1. Check of wheels and tires
Perform the following checks.

• Check of wheel and tire size

• Tire wear and deterioration

• Tire pressure check

NOTE: For the tire pressure, refer to the tire pressure label
attached to the lower section of driver's side door striker.

Q: Is the check result normal?

YES : Go to Step 2.
NO : Correct the wheels and tires. Then go to Step 9.

STEP 2. Check the DTC.
Using scan tool, check the diagnostic trouble code for ASC sys-
tem. (Refer to

P.35C-20

Q: Is the check result normal?

YES : Go to Step 3.
NO : Carry out the diagnosis for the DTC. (Refer to

P.35C-20

.) Then go to Step 9.

STEP 3. Check of brake-related components other than
hydraulic unit (integrated with ASC-ECU)
Perform the following checks, and also check that no non-gen-
uine parts are installed.

• Brake pad check (Refer to GROUP 35A − On-vehicle Ser-

vice, Brake Pad Check

P.35A-17

• Brake disc runout check (Refer to GROUP 35A − On-vehicle

Service, Brake Disc Rotor Check

P.35A-21

• Brake drag force check (Refer to GROUP 35A − On-vehicle

Service, Brake Drag Force Check

P.35A-24

Q: Is the check result normal?

YES : Go to Step 4.
NO : Repair or replace the trouble spot. Then go to Step 9.

STEP 4. Wheel alignment check
Perform the following checks, and also check that no non-gen-
uine parts are installed.

• Front wheel alignment check (Refer to GROUP 33 −

On-vehicle Service, Front Wheel Alignment Check and
Adjustment

P.33-7

• Rear wheel alignment check (Refer to GROUP 34 −

On-vehicle Service, Rear Wheel Alignment Check and
Adjustment

P.34-9

Q: Is the check result normal?

YES : Go to Step 5.
NO : Repair or replace the trouble spot. Then go to Step 9.

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-253

STEP 5. Check of wheel speed sensor
Check for the presence of non-genuine electronic components
and wiring harness of non-genuine electronic components to
near the wheel speed sensor (wheel speed detecting section
and wiring harness section). (Refer to

P.35C-274

Q: Is the check result normal?

YES : Go to Step 6.
NO : Remove the non-genuine electronic components and

wiring harness of non-genuine electronic
components. Then go to Step 9.

STEP 6. Scan tool service data
Check the following service data. (Refer to

P.35C-255

• Item 01: FL wheel speed sensor

• Item 02: FR wheel speed sensor

• Item 03: RL wheel speed sensor

• Item 04: RR wheel speed sensor

• Item 08: Lateral G sensor

• Item 10: Master cylinder pressure