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Mitsubishi Lancer (4A9 engine). Manual - part 52

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-61

• Adhesion of foreign materials on the wheel speed

sensor

• Adhesion of foreign materials on the wheel speed

detection encoder

• Malfunction of wheel speed sensor

• Improper installation of the wheel speed sensor

• ASC-ECU malfunction

• The number of poles on the Magnetic encoder for

wheel speed detection (N-pole and S-pole) is
changed

Past trouble

• When diagnosis code No.C1015 is also set, carry

out diagnosis with particular emphasis on wiring
harness and connector failures between ASC-
ECU and the wheel speed sensor. For diagnosis
procedures, refer to How to treat past trouble
(GROUP 00

− How to Use Troubleshooting/How

to Treat Past Trouble ).

• When diagnosis code No.C1015 is not set, the

following conditions may be present:

• Some wheels slip

• Unstable vehicle attitude

• External noise interference

• Vehicle ran with the parking brake applied.

• Rotate only two wheels with drum tester

PROBABLE CAUSES

• Wheel bearing malfunction

• Deformation of the wheel speed detection

encoder

• Missing teeth of the wheel speed detection

encoder

• Adhesion of foreign materials on the wheel speed

detection encoder

• ASC-ECU malfunction

• The number of poles on the Magnetic encoder for

wheel speed detection (N-pole and S-pole) is
changed

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.C1042 set?

YES :

Go to Step 3.

NO :

This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Check that diagnosis code No.C1015 is also set.

Q: Is diagnosis code No.C1015 also set?

YES :

Perform the diagnosis for diagnosis code

No.C1015 (Refer to

P.35C-23

NO :

Go to Step 4.

STEP 4. 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 5.

NO :

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

P.35C-188

). Then go to

Step 5.

STEP 5. Check for wheel speed sensor <FR>
output current
Refer to

P.35C-179

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Replace the wheel speed sensor <FR>
(Refer to

P.35C-188

). Then go to Step 9.

STEP 6. 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 7.

NO :

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

− Front Axle Hub Assembly ).

Then go to Step 10.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-62

STEP 7. Check of wheel speed detection encoder

AC504925

Oil seal

Magnetic
encoder

Wheel
bearing

Check the encoder for adhesion of foreign materials
or deformation.

Q: Is the check result normal?

YES :

Go to Step 8.

NO (Adhesion of foreign materials) :

Remove the

foreign materials and clean the encoder so
as not to disturb the magnetisation pattern
on it while taking care of the magnet,
magnetic substance, and magnetic
attraction. Then go to Step 10.

NO (Deformation) :

Replace the wheel bearing

<FR> (Refer to GROUP 26

− Front Axle

Hub Assembly ). Then go to Step 10.

STEP 8. 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 diagnosis code No. C1042 set?

YES :

Replace the wheel speed sensor <FR>

(Refer to

P.35C-188

). Then go to Step 9.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 9. 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 diagnosis code No. C1042 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

). Then go

to Step 10.

NO :

This diagnosis is complete.

STEP 10. 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 diagnosis code No. C1042 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. C1043: Abnormality in periodical signal for RL wheel speed sensor

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

and

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.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-63

DIAGNOSIS CODE SET CONDITIONS
ASC-ECU monitors the signals from each wheel
speed sensor while the vehicle is being driven. If any
fault below is found in these sensor signals, ASC-
ECU will set the relevant diagnosis code.

• Missing wheel speed sensor signal

• Wheel speed sensor signal continuously indi-

cates low value.

PROBABLE CAUSES

Current trouble

• Excessive gap between the wheel speed sensor

and the wheel speed detection encoder

• Adhesion of foreign materials on the wheel speed

sensor

• Wheel bearing malfunction

• Deformation of the wheel speed detection

encoder

• Adhesion of foreign materials on the wheel speed

detection encoder

• Malfunction of wheel speed sensor

• Improper installation of the wheel speed sensor

• ASC-ECU malfunction

• The number of poles on the Magnetic encoder for

wheel speed detection (N-pole and S-pole) is
changed

Past trouble

• When diagnosis code No.C1020 is also set, carry

out diagnosis with particular emphasis on wiring
harness and connector failures between ASC-
ECU and the wheel speed sensor. For diagnosis
procedures, refer to How to treat past trouble
(GROUP 00

− How to Use Troubleshooting/How

to Treat Past Trouble ).

• When diagnosis code No.C1020 is not set, the

following conditions may be present:

• Some wheels slip

• Unstable vehicle attitude

• External noise interference

• Vehicle ran with the parking brake applied.

• Rotate only two wheels with drum tester

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.C1043 set?

YES :

Go to Step 3.

NO :

This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Check that the diagnosis code No. C1020 is also set.

Q: Is the diagnosis code No. C1020 also set?

YES :

Perform the diagnosis for the diagnosis

code No. C1020 (Refer to

P.35C-27

NO :

Go to Step 4.

STEP 4. 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 5.

NO :

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

P.35C-188

). Then go to

Step 5.

STEP 5. Check for wheel speed sensor <RL>
output current
Refer to

P.35C-179

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Replace the wheel speed sensor <RL>
(Refer to

P.35C-188

). Then go to Step 9.

STEP 6. 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

−

Wheel Bearing Axial Play

Check ).

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

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

− Rear axle hub

assembly ). Then go to Step 10.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-64

STEP 7. Check of wheel speed detection encoder

AC700162

Rear hub

Oil seal

Ball bearing

Magnetic
encoder

Check the encoder for adhesion of foreign materials
or deformation.

Q: Is the check result normal?

YES :

Go to Step 8.

NO (Adhesion of foreign materials) :

Remove the

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

NO <Deformation> :

Replace the rear wheel hub

assembly <RL> (Refer to GROUP 27

−

Rear axle hub assembly ). Then go to Step
10.

STEP 8. 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 diagnosis code No. C1043 set?

YES :

Replace the wheel speed sensor (Refer to

P.35C-188

). Then go to Step 9.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 9. 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 diagnosis code No. C1043 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

). Then go

to Step 10.

NO :

This diagnosis is complete.

STEP 10. 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 diagnosis code No. C1043 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. C1044 Abnormality in periodical signal for RR wheel speed sensor

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

and

OPERATION

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

• 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.

Content .. 50 51 52 53 ..