Mitsubishi Lancer Evolution X. Manual - part 163

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-117

STEP 5. Voltage measurement at A-05 ASC-ECU connector
(1) Disconnect the ASC-ECU connector, connect the special 

tool ASC check harness (MB991997) to the wiring 
harness-side connector, and then measure 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 

power supply terminal (signal terminal) No. 43 and the body 
ground as well as between the ground terminal No. 42 and 
the body ground.

OK: 1 volt or less

Q: Is the check result normal?

YES  : Go to Step 6.
NO (Not normal at the terminal No. 43 or 42) : Go to Step 

7.

STEP 6. Resistance measurement at A-05 ASC-ECU 
connector
(1) Disconnect the ASC-ECU connector, connect the special 

tool ASC check harness (MB991997) to the wiring 
harness-side connector, and then measure 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. 43 and 
the body ground as well as between the ground terminal 
No. 42 and the body ground.

OK: No continuity

Q: Is the check result normal?

YES  : Go to Step 9.
NO (Not normal at the terminal No. 43 or 42) : Go to Step 

7.

AC400817CK

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

AC400817CL

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-118

STEP 7. Connector check: A-05 ASC-ECU connector, C-47 
intermediate connector, D-09 wheel speed sensor <RR> 
connector
Q: Is the check result normal?

YES : Go to Step 8.
NO :  Repair the defective connector. Then go to Step 17.

STEP 8. Wiring harness check between A-05 ASC-ECU 
connector terminal No. 43 and D-09 wheel speed sensor 
<RR> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 42 and D-09 wheel speed 
sensor <RR> connector terminal No. 2

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

Q: Is the check result normal?

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

P.35C-300

.) Then go to Step 17.

NO :  Repair the wiring harness. Then go to Step 17.

STEP 9. Voltage measurement at A-05 ASC-ECU connector
(1) Disconnect the ASC-ECU connector, connect the special 

tool ASC check harness (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. 43 and 
the body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 10.
NO :  Go to Step 12.

STEP 10. Wiring harness check between A-05 ASC-ECU 
connector terminal No. 43 and D-09 wheel speed sensor 
<RR> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 42 and D-09 wheel speed 
sensor <RR> connector terminal No. 2

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

Q: Is the check result normal?

YES : Go to Step 11.
NO :  Repair the wiring harness. Then go to Step 17.

AC400817CM

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-119

STEP 11. Check of wheel speed sensor as a single unit
Refer to 

P.35C-303

.

Q: Is the check result normal?

YES : Go to Step 13.
NO :  Replace the wheel speed sensor <RR>. (Refer to 

P.35C-300

.) Then go to Step 17.

STEP 12. Connector check: A-05 ASC-ECU connector, 
C-47 intermediate connector, D-09 wheel speed sensor 
<RR> connector
Q: Is the check result normal?

YES : Go to Step 16.
NO :  Repair the defective connector. Then go to Step 17.

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-300

.) 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 detection 
magnet encoder.

•

Check the wheel bearing <RR> for looseness. (Refer to 
GROUP 27 

−

 On-vehicle Service 

P.27-32

.)

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.27-35

.)

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.27-35

.)

AC608248AB

Magnetic
encoder

Rear Wheel
bearing

Rear wheel
hub
assembly

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-120

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-298

.) 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.

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 

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.