Mitsubishi Lancer (4A9 engine). Manual - part 69

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-129

(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. C1608 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to step 10.

NO : 

Go to step 11.

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. C1608 set?

YES : 

Return to Step 1.

NO  : 

Go to step 11.

STEP 11. Check the other diagnosis code.
(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 any diagnosis code set?

YES : 

Carry out the applicable troubleshooting for 

the diagnosis code (Refer to ).

NO  : 

The procedure is complete.

Code No. U0001 Bus-off

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 diagnosis code U0001 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 reliable.

• Before replacing the ECU, ensure that the 

communication circuit is 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

).

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASC-ECU has 
ceased the CAN communication (bus off).

COMMENTS ON TROUBLE SYMPTOM
Malfunction of wiring harness, connector (s), or ASC-
ECU may be present.

PROBABLE CAUSES

• Wiring harness or connector failure of CAN bus 

line

• ASC-ECU malfunction

• Other ECU malfunction

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 2.

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C 

− CAN Bus Diagnostics Table ). On 

completion, go to Step 3.

STEP 2. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No. U0001 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

), and then 

go to Step 3.

NO : 

If the trouble symptom is resolved, an 
intermittent malfunction such as poorly 
engaged connector(s) or wiring harness is 
suspected (Refer to GROUP 00 

− How to 

Use Troubleshooting/How to Cope with 
Intermittent Malfunctions ).

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-130

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

Q: Is diagnosis code No. U0001 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No.U0404: Abnormality in AS&G signal

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.

OPERATION
AS&G-ECU outputs the signal to ASC-ECU via the 
CAN bus lines.

DIAGNOSIS CODE SET CONDITION
This diagnosis code is set when abnormality in 
AS&G-ECU output value if any malfunction below is 
found:

PROBABLE CAUSES

• Wiring harness or connector failure of CAN bus 

line

• AS&G-ECU 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.U0404 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. ETACS-ECU coding data check
Refer to GROUP 00 

− Coding List .

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Replace the ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU .), and then go to Step 

6.

STEP 4. M.U.T.-III other system diagnosis code
Use M.U.T.-III to check whether any diagnosis code 
related to vehicles information is set or not by the 
AS&G-ECU.

Q: Is the diagnosis code set?

YES : 

Troubleshoot for the relevant diagnosis 

code, and then go to Step 5.

NO : 

Go to Step 5.

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

Q: Is diagnosis code No.U0404 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

.), and then 

go to Step 6.

NO : 

This diagnosis is complete.

STEP 6. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.U0404 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-131

Code No. U0100 Engine time-out error

 

Code No. U0101 CVT or A/T time-out error

 

Code No. U0126 Steering wheel sensor time-out error

 

Code No. U0141 ETACS time-out error

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 diagnosis codes U0100, U0101, U0126 and 

U0141 are 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 reliable.

• Before replacing the ECU, ensure that the 

communication circuit is 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

).

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if ASC-ECU cannot 
receive the signal sent from other ECU for a certain 
period.

OPERATION
ASC-ECU communicates with the engine ECU, CVT 
or A/T, the steering wheel sensor or ETACS-ECU via 
the CAN bus lines.

PROBABLE CAUSES

Code No. U0100

• Wiring harness or connector failure of CAN bus 

line

• Engine ECU malfunction

• ASC-ECU malfunction

• Connector disconnected or improperly connected

• Stretched or broken wires

Code No. U0101

• Wiring harness or connector failure of CAN bus 

line

• CVT or A/T malfunction

• ASC-ECU malfunction

• Connector disconnected or improperly connected

• Stretched or broken wires

Code No. U0126

• Wiring harness or connector failure of CAN bus 

line

• Steering wheel sensor malfunction

• ASC-ECU malfunction

• Connector disconnected or improperly connected

• Stretched or broken wires

Code No. U0141

• Wiring harness or connector failure of CAN bus 

line

• Malfunction of ETACS-ECU

• ASC-ECU malfunction

• Connector disconnected or improperly connected

• Stretched or broken wires

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 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: Are Code No. U0100, U0101, U0126 or U0141 set?

YES : 

Go to Step 3.

NO : 

The procedure is complete.

STEP 3. M.U.T.-III other system diagnosis code
Use M.U.T.-III to check that other diagnosis code is 
set in the ECU corresponding to the relevant diagno-
sis.

Q: Is other diagnosis code set?

YES : 

Troubleshoot for the relevant diagnosis 

code.

NO : 

Go to Step 4.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-132

STEP 4. M.U.T.-III diagnosis code
Use M.U.T.-III to check if the same diagnosis code 
(time-out) is set in the other ECU (CAN-C).

Q: Is any diagnosis code set?

YES (Code No. U0100 is set) : 

Replace the engine 

ECU, and then go to Step 5.

YES (Code No. U0101 is set) : 

Replace the CVT or 

A/T, and then go to Step 5.

YES (Code No. U0126 is set) : 

Replace steering 

wheel sensor, and then go to Step 5.

YES (Code No. U0141 is set) : 

Replace the 

ETACS-ECU, and then go to Step 5.

NO (No diagnosis code is set.) : 

The procedure is 

complete.

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

Q: Are Code No. U0100, U0101, U0126 or U0141 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

).

NO : 

The procedure is complete.

Code No. U1004 AS&G CAN time-out

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 diagnosis codes U1004 are 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 reliable.

• Before replacing the ECU, ensure that the 

communication circuit is 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.

OPERATION
ASC-ECU communicates with the AS&G-ECU via 
the CAN bus lines.

DIAGNOSIS CODE SET CONDITION
This diagnosis code is set if ASC-ECU cannot 
receive the signal sent from AS&G-ECU for a certain 
period.

PROBABLE CAUSES

• Wiring harness or connector failure of CAN bus 

line

• AS&G-ECU malfunction

• ASC-ECU malfunction

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 2.

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C 

− CAN Bus Diagnostics Table .). On 

completion, go to Step 2.

STEP 2. ETACS-ECU coding data check
Refer to GROUP 00 

− Coding List .

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Replace the ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU .), and then go to Step 

6.

STEP 3. M.U.T.-III other system diagnosis code
Use M.U.T.-III to check that other diagnosis code is 
set in the AS&G-ECU corresponding to the relevant 
diagnosis.

Q: Is other diagnosis code set?

YES : 

Troubleshoot for the relevant diagnosis 

code, and then go to Step 4.

NO : 

Go to Step 4.

STEP 4. M.U.T.-III diagnosis code
Use M.U.T.-III to check if the same diagnosis code 
(time-out) is set in the other ECU (CAN-C).

Q: Is any diagnosis code set?