Mitsubishi Lancer (4A9 engine). Manual - part 67

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-121

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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 diagnosis code No.C1219 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Check that the wheel speed sensor-related, G and 
yaw rate sensor-related, or steering wheel sensor-
related diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Troubleshoot the relevant diagnosis code, 

and then go to Step 8.

NO : 

Go to Step 4.

STEP 4. Check how steering wheel sensor is 
installed.
Check that the steering wheel sensor is installed cor-
rectly (Refer to 

P.35C-190

).

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Install the steering wheel sensor correctly 
(Refer to 

P.35C-190

), and then go to Step 5.

STEP 5. G and yaw rate sensor installation check
Check that the G and yaw rate sensor is installed 
correctly.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Reinstall the G and yaw rate sensor 
correctly (Refer to 

P.35C-189

), and then go 

to Step 6.

STEP 6. Wheel alignment check

Q: Is the check result normal?

YES : 

After the wheel alignment check, perform 

the steering wheel sensor calibration to 
make ASC-ECU learn the neutral point 
again (Refer to 

P.35C-183

). Then go to Step 

7.

NO : 

After the adjustment of the wheel alignment, 
perform the steering wheel sensor 
calibration to make ASC-ECU learn the 
neutral position again (Refer to 

P.35C-183

). 

Then go to Step 7.

STEP 7. M.U.T.-III data list
Check the following data list (Refer to 

P.35C-172

).

• Item 11: Steering angle

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

After the steering wheel sensor is replaced, 
perform the steering wheel sensor 
calibration to make ASC-ECU learn the 
neutral point again (Refer to 

P.35C-183

). 

Then go to Step 9.

STEP 8. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

Q: Is diagnosis code No.C1219 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

), and then 

go to Step 9.

NO : 

This diagnosis is complete.

STEP 9. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

Q: Is diagnosis code No.C1219 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-122

Code No. C121A Abnormality in steering wheel sensor calibration

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 steering wheel sensor is replaced, 

always carry out calibration to make ASC-
ECU learn the neutral point (Refer to 

P.35C-

183

).

• 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
Steering wheel sensor stores the neutral position 
learned by M.U.T.-III. When the neutral position has 
not been stored in the steering wheel sensor yet, the 
steering wheel sensor outputs the signal indicating 
that it does not have neutral position.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASC-ECU detects 
that the steering wheel sensor has not learned the 
neutral position yet.

PROBABLE CAUSES

• Neutral position of steering wheel sensor not 

learned

• Steering wheel sensor malfunction

• ASC-ECU malfunction

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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 diagnosis code No.C121A set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. Steering wheel sensor calibration
Perform calibration of steering wheel sensor (Refer 
to 

P.35C-183

).

Q: Has the calibration succeeded?

YES : 

Go to Step 4.

NO : 

After the steering wheel sensor is replaced, 
perform the steering wheel sensor 
calibration to make ASC-ECU learn the 
neutral point again (Refer to 

P.35C-183

). 

Then go to Step 4.

STEP 4. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C121A set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

), and then 

go to Step 5.

NO : 

This diagnosis is complete.

STEP 5. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C121A set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-123

Code No. C2205: Internal malfunction of steering wheel 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 steering wheel sensor is replaced, 

always carry out calibration to make ASC-
ECU learn the neutral point (Refer to 

P.35C-

183

).

• 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
Steering wheel sensor sends its status signal to 
ASC-ECU.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASC-ECU detects 
that the steering wheel sensor has malfunction.

PROBABLE CAUSES

• Steering wheel sensor malfunction

• ASC-ECU malfunction

• External noise interference

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C 

− CAN Bus Diagnostics Table ). On 

completion, go to Step 4.

STEP 2. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code No.C2205 set?

YES : 

Replace the steering wheel sensor (Refer to 

P.35C-190

), and then go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C2205 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

), and then 

go to Step 4.

NO : 

This diagnosis is complete.

STEP 4. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C2205 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No.C2002: Valve calibration not completed

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
Perform the master cylinder pressure sensor calibra-
tion to store the calibrated value in the ASC-ECU. At 
the same time, the calibrated value of cut valve and 
inlet valve are stored.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-124

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the calibrated values 
for cut valve and inlet valve stored in ASC-ECU are 
not within the predetermined range.

PROBABLE CAUSES

• ASC-ECU malfunction

• Noise interference

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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 diagnosis code No.C2002 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 3.

NO : 

This diagnosis is complete.

STEP 3. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C2002 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No.C2003: Control parameter not implement

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 ).

• 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.

• If diagnosis code No.C2003 is set in ASC-

ECU, always diagnose the CAN bus line. If 
there is any fault in the CAN bus lines, an 
incorrect diagnosis code may be set. In this 
case, the set diagnosis code is not highly reli-
able.

• Before replacing the ECU, ensure that the 

communication circuit is normal.

• When diagnosis code No.C2003 is set in ASC-

ECU, the diagnosis code may also be set in 
ETACS-ECU. When the diagnosis code is set 
in ETACS-ECU, carry out the diagnosis of the 
diagnosis code for ETACS-ECU first.

• 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

ASC-ECU receives the vehicle information stored in 
the ETACS-ECU via CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
When received unset coding data from the ETACS-
ECU, this diagnosis code is set.

PROBABLE CAUSES

• Malfunction of ETACS-ECU

• Engine ECU malfunction

• ETACS-ECUs have been interchanged between 

two vehicles.

• ASC-ECU malfunction

• ASC-ECUs have been interchanged between two 

vehicles.

• ETACS-ECU or ASC-ECU installation error

• Malfunction of ETACS-ECU coding data

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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.