Mitsubishi Evolution X. Manual - part 761

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-51

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C101C set?

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

STEP 3. Scan tool diagnostic trouble code
Check if DTC No. C1015 is also set.
Q: Is DTC C1015 also set?

YES : Carry out the diagnosis for code No. C1015. ( Refer to 

P.35C-28

.)

NO :  Go to Step 4.

STEP 4. Check of wheel speed sensor installation status
Check the installation status of wheel speed sensor <FR> (dis-
connection of wheel speed sensor, looseness of mounting bolt, 
etc.).
Q: Is the check result normal?

YES : Go to Step 5.
NO :  Reinstall the wheel speed sensor <FR> correctly. 

(Refer to 

P.35C-274

.) Then go to Step 16.

STEP 5. Check of wheel speed sensor as a single unit
Refer to 

P.35C-277

.

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Replace the wheel speed sensor <FR>. (Refer to 

P.35C-274

.) Then go to Step 16.

STEP 6. 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 <FR> for loose-
ness. (Refer to GROUP 26 

−

 On-vehicle Service 

P.26-7

.)

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Replace the front hub assembly. (Refer to GROUP 26 

− Front Axle Hub Assembly 

P.26-9

.)

STEP 7. 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 8.
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 front hub assembly. (Refer 

to GROUP 26 

− Front Axle Hub Assembly 

P.26-9

.)

AC704652 AB

Oil seal

Magnetic 
encoder

Wheel 
bearing

Hub

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-52

STEP 8. Voltage measurement at 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) Turn the ignition switch to the ON position.
(3) Measure the voltage between the wheel speed sensor 

circuit power supply terminal (signal terminal) No. 34 and 
the body ground as well as between the ground terminal 
No. 33 and the body ground.

OK: 1 volt or less

Q: Is the check result normal?

YES  : Go to Step 9.
NO (Not normal at the terminal No. 34 or 33) : Go to Step 

10.

STEP 9. Resistance measurement at 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 resistance between the wheel speed sensor 

circuit power supply terminal (signal terminal) No. 34 and 
the body ground as well as between the ground terminal 
No. 33 and the body ground.

OK: No continuity

Q: Is the check result normal?

YES  : Go to Step 12.
NO (Not normal at the terminal No. 34 or 33) : Go to Step 

10.

AC400817CE

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

AC400817CF

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

DIAGNOSIS

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-53

STEP 10. Connector check: A-05 ASC-ECU connector, 
A-03 wheel speed sensor <FR> connector
Q: Is the check result normal?

YES : Go to Step 11.
NO :  Repair the defective connector. Then go to Step 16.

STEP 11. Wiring harness check between A-05 ASC-ECU 
connector terminal No. 34 and A-03 wheel speed sensor 
<FR> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 33 and A-03 wheel speed 
sensor <FR> connector terminal No. 2

• Short circuit check of wheel speed sensor <FR> circuit

Q: Is the check result normal?

YES : Replace the wheel speed sensor <FR>. (Refer to 

P.35C-274

.) Then go to Step 16.

NO :  Repair the wiring harness. Then go to Step 16.

STEP 12. Voltage measurement at A-05 ASC-ECU 
connector
(1) Disconnect the ASC-ECU connector, connect the ASC 

check harness (Special tool: MB991997) to the 
ASC-ECU-side connector and the wiring harness-side 
connector, and then measure at the special tool connector 
side.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the wheel speed sensor 

circuit power supply terminal (signal terminal) No. 34 and 
the body ground.

OK: System voltage

Q: Is the check result normal?

YES : Go to Step 13.
NO :  Go to Step 15.

STEP 13. Connector check: A-05 ASC-ECU connector, 
A-03 wheel speed sensor <FR> connector
Q: Is the check result normal?

YES : Go to Step 14.
NO :  Repair the defective connector. Then go to Step 16.

AC400817CG

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-54

STEP 14. Wiring harness check between A-05 ASC-ECU 
connector terminal No. 34 and A-03 wheel speed sensor 
<FR> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 33 and A-03 wheel speed 
sensor <FR> connector terminal No. 2

• Open circuit check of wheel speed sensor <FR> circuit

Q: Is the check result normal?

YES : Go to Step 15.
NO :  Repair the wiring harness. Then go to Step 16.

STEP 15. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(2) 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 C101C set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-272

.) Then go to Step 16.

NO :  Intermittent malfunction. (Refer to GROUP 00 

− How 

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 16. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(2) 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 C101C set?

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