Mitsubishi Lancer (4A9 engine). Manual - part 54

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-69

STEP 5. Connector check: A-58 ASC-ECU 
connector, A-08 front wheel speed sensor <LH> 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the defective connector. Then go to 
Step 13.

STEP 6. Wiring harness check between A-58 
ASC-ECU connector terminal No.45 and A-08 
front wheel speed sensor <LH> connector 
terminal No.1 and between A-58 ASC-ECU 
connector terminal No.46 and A-08 front wheel 
speed sensor <LH> connector terminal No.2.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the wiring harness. Then go to Step 
13.

STEP 7. Check for wheel speed sensor <FL> 
installation
Check how the wheel speed sensor <FL> is installed 
(Disconnection of wheel speed sensor <FL>, loose 
mounting bolt, etc.).

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Reinstall the wheel speed sensor <FL> 
correctly (Refer to 

P.35C-188

). Then go to 

Step 8.

STEP 8. Check for wheel speed sensor <FL> 
output current
Refer to 

P.35C-179

.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Replace the wheel speed sensor <FL> 
(Refer to 

P.35C-188

). Then go to Step 12.

STEP 9. Check for wheel bearing looseness
NOTE: Loose wheel bearing may increase the gap 
between the wheel speed sensor <FL> and the 
wheel speed detection magnet encoder. Check the 
wheel bearing <FL> for looseness. (Refer to GROUP 
26 

−

 Wheel Bearing Axial Play Check .)

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Replace the wheel bearing <FL> (Refer to 
GROUP 26 

− Front Axle Hub Assembly ). 

Then go to Step 13.

STEP 10. Check of wheel speed detection 
encoder

AC504925

Oil seal

Magnetic
encoder

AC

Wheel
bearing

Check the encoder for adhesion of foreign materials 
or deformation.

Q: Is the check result normal?

YES : 

Go to Step 11.

NO (Adhesion of foreign materials) : 

Remove the 

foreign materials and clean the encoder so 
as not to disturb the magnetization pattern 
on it while taking care of the magnet, 
magnetic substance, and magnetic 
attraction. Then go to Step 13.

NO (Deformation) : 

Replace the wheel bearing 

<FL> (Refer to GROUP 26 

− Front Axle Hub 

Assembly ). Then go to Step 13.

STEP 11. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

NOTE: The ABS warning lamp does not turn OFF 
in some cases unless the vehicle runs at 20 km/h 
or higher.

Q: Is the diagnosis code No.C1046 set?

YES : 

Replace the wheel speed sensor <FL> 

(Refer to 

P.35C-188

). Then go to Step 12.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use Troubleshooting/How to 

Cope with Intermittent Malfunctions).

STEP 12. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

NOTE: The ABS warning lamp does not turn OFF 
in some cases unless the vehicle runs at 20 km/h 
or higher.

Q: Is the diagnosis code No.C1046 set?

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-70

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 13.

NO : 

This diagnosis is complete.

STEP 13. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.

(2) Drive the vehicle at 20 km/h or higher.

NOTE: The ABS warning lamp does not turn OFF 
in some cases unless the vehicle runs at 20 km/h 
or higher.

Q: Is the diagnosis code No.C1046 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No. C1047 FR wheel speed sensor control phase time exceeded

Wheel Speed Sensor Circuit

ASC-ECU

(LH)

(LH)

(RH)

(RH)

FRONT WHEEL SPEED SENSOR

REAR WHEEL SPEED SENSOR

Wire colour code 
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue 
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple     SI : Silver

ACB02565

AC612691

AP

Connectors: A-03, A-58 <LHD>

A-03 (B)

A-58 (B)

AC701237AE

Connector: A-03 <RHD>

A-03 (B)

AC701238 AF

Connector: A-58 <RHD>

A-58 (B)

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-71

CAUTION

• If there is any problem in the CAN bus lines, 

an incorrect diagnosis code may be set. Prior 
to this diagnosis, diagnose the CAN bus lines 
(Refer to GROUP 54C 

− CAN Bus Diagnostics 

Table ).

• Whenever ECU is replaced, ensure that the 

CAN bus lines are normal.

• When the hydraulic unit (integrated with ASC-

ECU) is replaced, always carry out the calibra-
tion of the steering wheel sensor, the G and 
yaw rate sensor and brake fluid pressure sen-
sor (Refer to 

P.35C-182

, 

P.35C-183

 and 

P.35C-

184

).

OPERATION

• The wheel speed sensor is a kind of a pulse gen-

erator. It consists of encoders (a plate on which 
north and south pole sides of the magnets are 
arranged alternately) for detecting the wheel 
speed which rotates at the same speed of the 
wheels and wheel speed sensors. This sensor 
outputs frequency pulse signals in proportion to 
the wheel speed.

• The pulse signals, which the wheel speed sensor 

creates, are sent to ASC-ECU. ASC-ECU uses 
the frequency of the pulse signals to determine 
the wheel speed.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if any malfunction below is 
found:

• When the brake fluid pressure is decreased for a 

long time.

• When the brake fluid pressure is held for a long 

time.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• External noise interference

• Malfunction of wheel speed sensor

• ASC-ECU malfunction

• Excessive gap between the wheel speed sensor 

and the magnetic encoder for wheel speed detec-
tion

• Adhesion of foreign materials on the wheel speed 

sensor

• Adhesion of foreign materials on the magnetic 

encoder for wheel speed detection

• Wheel bearing malfunction

• Improper installation of the wheel speed sensor

• Deformation of the magnetic encoder for wheel 

speed detection

• Disturbance of magnetization pattern for mag-

netic encoder for wheel speed detection

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-72

• Missing teeth of the magnetic encoder for wheel 

speed detection

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to 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 

− CAN Bus Diagnostics Table ). On 

completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting 
CAN bus lines

Q: Is the diagnosis code No.C1047 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Check that the diagnosis codes No.C1015, C101C, 
C101F, and C1042 are also set.

Q: Are the diagnosis codes No.C1015, C101C, C101F, 

and C1042 also set?
YES : 

Carry out the diagnosis for the relevant 

diagnosis codes.

NO : 

Go to Step 4.

STEP 4. M.U.T.-III data list
Check the following data list (Refer to 

P.35C-172

).

• Item No.02: FR wheel speed sensor

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Go to Step 5.

STEP 5. Connector check: A-58 ASC-ECU 
connector, A-03 front wheel speed sensor <RH> 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the defective connector. Then go to 
Step 13.

STEP 6. Wiring harness check between A-58 
ASC-ECU connector terminal No.34 and A-03 
front wheel speed sensor <RH> connector 
terminal No.1 and between A-58 ASC-ECU 
connector terminal No.33 and A-03 front wheel 
speed sensor <RH> connector terminal No.2.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the wiring harness. Then go to Step 
13.

STEP 7. Check for wheel speed sensor <FR> 
installation
Check how the wheel speed sensor <FR> is installed 
(Disconnection of wheel speed sensor <FR>, loose 
mounting bolt, etc.).

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Reinstall the wheel speed sensor <FR> 
correctly (Refer to 

P.35C-188

). Then go to 

Step 8.

STEP 8. Check for wheel speed sensor <FR> 
output current
Refer to 

P.35C-179

.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Replace the wheel speed sensor <FR> 
(Refer to 

P.35C-188

). Then go to Step 12.

STEP 9. Check for wheel bearing looseness
NOTE: Loose wheel bearing may increase the gap 
between the wheel speed sensor <FR> and the 
wheel speed detection magnet encoder. Check the 
wheel bearing <FR> for looseness. (Refer to 
GROUP 26 

−

 Wheel Bearing Axial Play Check .)

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Replace the wheel bearing <FR> (Refer to 
GROUP 26 

− Front Axle Hub Assembly ). 

Then go to Step 13.

STEP 10. Check of wheel speed detection 
encoder

AC504925

Oil seal

Magnetic
encoder

AC

Wheel
bearing

Check the encoder for adhesion of foreign materials 
or deformation.

Q: Is the check result normal?