Mitsubishi Evolution X. Manual - part 760

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-47

STEP 10. Connector check: A-05 ASC-ECU connector, A-11 
wheel speed sensor <FL> 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. 45 and A-11 wheel speed sensor 
<FL> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 46 and A-11 wheel speed 
sensor <FL> connector terminal No. 2

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

Q: Is the check result normal?

YES : Replace the wheel speed sensor <FL>. (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. 45 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-11 
wheel speed sensor <FL> connector
Q: Is the check result normal?

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

AC400817CD

ASC-ECU

MB991997

Check harness

A-05 ASC-ECU
harness connector

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-48

STEP 14. Wiring harness check between A-05 ASC-ECU 
connector terminal No. 45 and A-11 wheel speed sensor 
<FL> connector terminal No. 1, and between A-05 
ASC-ECU connector terminal No. 46 and A-11 wheel speed 
sensor <FL> connector terminal No. 2

• Open circuit check of wheel speed sensor <FL> 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 C1011 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 C1011 set?

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

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-49

DTC C101C: Abnormality in FR wheel speed sensor signal

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

• Each wheel speed detecting section is a kind of a pulse 

generator. It consists of the encoder (plate on which the 
north and south pole of magnet are arranged alternately) for 
detecting the wheel speed, which rotates at the same speed 
of the wheels, and the wheel speed sensor. This detecting 
section outputs the frequency pulse signals in proportion to 
the wheel speed.

• The pulse signals generated by the wheel speed detecting 

section are sent to ASC-ECU. ASC-ECU uses the fre-
quency of the pulse signals to determine the wheel speed.

.

DTC SET CONDITIONS

ASC-ECU monitors the signals from each wheel speed sensor 
while the vehicle is being driven. If any abnormality below is 
detected in the sensor signals, ASC-ECU sets the relevant 
diagnostic trouble code.

• Irregular change in the wheel speed sensor signal

• Wheel speed sensor signal continuously indicates higher 

value than the values of other wheel speed sensors.

.

AC708948

A-05 (B)

AC

Connectors: A-03, A-05

A-03 (B)

DIAGNOSIS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-50

PROBABLE CAUSES

Current trouble

• Excessive gap between the wheel speed sensor and the 

magnetic encoder for wheel speed detection

• Adhesion of foreign materials on the wheel speed sensor

• Adhesion of foreign materials on the magnetic encoder for 

wheel speed detection

• Wheel bearing malfunction

• Malfunction of wheel speed sensor

• Damaged wiring harness and connectors

• External noise interference

• Improper installation of the wheel speed sensor

• Deformation of the magnetic encoder for wheel speed 

detection

• ASC-ECU malfunction

• Disturbance of magnetization pattern for magnetic encoder 

for wheel speed detection

• The number of poles on the magnetic encoder for wheel 

speed detection (the number of N-pole and S-pole) is 
changed.

Past trouble

• When the DTC No. C1015 is also set, perform the diagnosis 

with a particular emphasis on the wiring harness and con-
nector failures between ASC-ECU and the wheel speed 
sensor. For diagnosis procedures, refer to How to Treat 
Past Trouble (GROUP 00 

− How to Use Troubleshoot-

ing/Inspection Service Points 

P.00-16

).

• When diagnostic trouble code No.C1015 is not set, the fol-

lowing conditions may be present:

• Wheel(s) spinning

• Unstable vehicle attitude (spin)

• External noise interference

• Vehicle ran with the parking brake applied.

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.