Mitsubishi Lancer (4A9 engine). Manual - part 55

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-73

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 

<FR> (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.C1047 set?

YES : 

Replace the wheel speed sensor <FR> 

(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.C1047 set?

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.C1047 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-74

Code No. C1048 RL 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

AO

Connector: A-58 <LHD>

A-58 (B)

AC701238 AF

Connector: A-58 <RHD>

A-58 (B)

AC612705

Connector: C-31 <LHD>

AF

AC701121

Connector: C-31 <RHD>

AM

AC612723

AU

Connector: D-17

AC612744 BH

Connector: F-24 <LANCER>

      (B)

AC801775BM

       (B)

Connector: F-24 <LANCER SPORTBACK>

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-75

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 wheel speed detection encoder

• Adhesion of foreign materials on the wheel speed 

sensor

• Adhesion of foreign materials on the wheel speed 

detection encoder

• Wheel bearing malfunction

• Improper installation of the wheel speed sensor

• Deformation of the wheel speed detection 

encoder

• Disturbance of magnetisation pattern for wheel 

speed detection encoder

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-76

• Missing teeth of the wheel speed detection 

encoder

DIAGNOSIS 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.C1048 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. C1020, C1027, 
C102A, and C1043 are also set.

Q: Are the diagnosis codes No. C1020, C1027, C102A, 

and C1043 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.03: RL 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, C-31 intermediate connector, D-17 
intermediate connector, F-24 rear 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.36 and F-24 rear 
wheel speed sensor <LH> connector terminal 
No.1, and between A-58 ASC-ECU connector 
terminal No.37 and F-24 rear 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 <RL> 
installation
Check how the wheel speed sensor <RL> is installed 
(Disconnection of wheel speed sensor <RL>, loose 
mounting bolt, etc.).

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

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

P.35C-188

). Then go to 

Step 8.

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

P.35C-179

.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Replace the wheel speed sensor <RL> 
(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 <RL> and the 
wheel speed detection magnet encoder.

•

Check the Rear wheel hub assembly <RL> 
(Refer to GROUP 27 

−

 On-vehicle Service ).

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Replace the rear wheel hub assembly <RL> 
(Refer to GROUP 27 

− Rear axle hub 

assembly ). Then go to Step 13.