Mitsubishi Lancer (4A9 engine). Manual - part 63

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-105

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. C2101 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. Battery check
Refer to GROUP 54A 

− Battery Test .

Q: Is the battery in good condition?

YES : 

Go to Step 5.

NO : 

Charge or replace the battery. Then go to 
Step 4.

STEP 4. Charging system check
Refer to GROUP 16 

− On−vehicle Service/Alternator 

Output Line Voltage Drop Test .

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair or replace the charging system 
component(s).

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

Q: Is the diagnosis code No. C2101 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 6.

NO : 

The trouble can be an intermittent 
malfunction (Refer to GROUP 00 

− How to 

Use Troubleshooting/How to Cope with 
Intermittent Malfunctions ).

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

Q: Is the diagnosis code No. C2101 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No. C1395 Brake fluid filling 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

).

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the brake fluid is not 
filled in the hydraulic unit.

PROBABLE CAUSES

• Different hydraulic unit (For delivery to factory)

• 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. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is the diagnosis code No. C1395 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

).

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-106

Code No. C121C Torque request signal rejection

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.

• Do not drop or shock the G and yaw rate sen-

sor.

• When the G and yaw rate sensor is replaced, 

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

P.35C-

182

).

• 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 sends the signal to the engine ECU as 
necessary to decrease the engine output for the ASC 
system operation.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the request for the 
decrease of output is rejected by the engine ECU.

PROBABLE CAUSES

• Wrong coding of engine ECU

• Engine ECU malfunction

• ASC-ECU malfunction

• External noise interference

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 diagnosis code No.C121C set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

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

Q: Is the diagnosis code set?

YES : 

Troubleshoot the engine ECU (Refer to 

GROUP 13A 

− Troubleshooting/Diagnosis 

function  <4A9>, GROUP 13B 

− 

Troubleshooting/Diagnosis function  <4B1>, 
GROUP 13F 

− Troubleshooting/Diagnosis 

function  <4J1> or GROUP 13C 

− 

Troubleshooting/Diagnosis function  
<4N1>), and then go to Step 7.

NO : 

Go to Step 4.

STEP 4. M.U.T.-III diagnosis code
Check that diagnosis code No.U1417 is set in ASC-
ECU.

Q: Is diagnosis code No.U1417 set?

YES : 

Troubleshoot for diagnosis code No.U1417 

(Refer to 

P.35C-140

). Then go to Step 5.

NO : 

Replace the hydraulic unit (integrated with 
ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 7.

STEP 5. M.U.T.-III data list
Check the following data list (Refer to 

P.35C-172

).

• Item 68: Allow ESP torque request

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace the engine ECU (Refer to GROUP 
13A 

− engine ECU  <4A9>, GROUP 13B − 

engine ECU  <4B1>, GROUP 13F 

− engine 

ECU  <4J1> or GROUP 13C 

− engine ECU  

<4N1>), and then go to Step 7.

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

Q: Is diagnosis code No.C121C set?

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-107

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 7.

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 ).

STEP 7. Diagnosis code recheck
Erase the diagnosis code.

Q: Is diagnosis code No.C121C set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No. C1290 CAN 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 the diagnosis code No.C1290 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.

• 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

).

• When the diagnosis code No.C1290 is set in 

ASC-ECU, the diagnosis code for another 
system may also be set. When the diagnosis 
code for another system is set, carry out diag-
nosis for that system first.

OPERATION
ASC-ECU receives signals necessary for the opera-
tions of ABS, ASC, and TCL from the engine ECU, 
CVT-ECU or A/T-ECU, AS&G-ECU, ETACS-ECU, 
and the steering wheel sensor via the CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
ASC-ECU receives signals necessary for the opera-
tions of ABS, ASC, and TCL from the engine ECU, 
CVT-ECU or A/T-ECU, AS&G-ECU, ETACS-ECU, 
and steering wheel sensor via CAN bus lines. This 
diagnosis code is stored when ASC-ECU cannot 
receive the signals necessary for the operations of 
ABS, ASC, and TCL from the engine ECU, CVT-ECU 
or A/T-ECU, AS&G-ECU, ETACS-ECU, and steering 
wheel sensor.

PROBABLE CAUSES

• Engine ECU malfunction

• CVT-ECU or A/T-ECU malfunction

• AS&G-ECU malfunction

• Steering wheel sensor malfunction

• Malfunction of the CAN bus

• ASC-ECU malfunction

• Malfunction of ETACS-ECU

• ETACS-ECUs have been interchanged between 

two vehicles.

• 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 6.

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis codes U0100, U0101, 
U0126, U0141 or U1004 are set in ASC-ECU.

Q: Is the diagnosis code set?

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-108

YES : 

Troubleshoot for the relevant diagnosis 

code (Refer to 

P.35C-16

). Then go to Step 

6.

NO : 

Go to Step 3.

STEP 3. M.U.T.-III other system diagnosis code
Using M.U.T.-III, check if the diagnosis codes are set 
from the engine ECU, CVT-ECU or A/T-ECU, AS&G-
ECU, ETACS-ECU, and steering wheel sensor or 
not.

Q: Is the diagnosis code set?

YES : 

Troubleshoot the relevant diagnosis code, 

and then go to Step 6.

NO : 

Go to Step 4.

STEP 4. ETACS-ECU coding data check
Refer to GROUP 00 

− Precautions before Service/

Coding List .

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Replace the ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ), and then go to Step 6.

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

Q: Is the diagnosis code No.C1290 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 6.

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 ).

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

Q: Is the diagnosis code No.C1290 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

Code No. C2203 VIN not recorded

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 ).

• When other diagnosis code for ASC-ECU is 

set, troubleshoot that diagnosis code first.

• 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
ASC-ECU receives vehicle information from the 
engine ECU and stores it.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASC-ECU cannot 
receive the vehicle information from the engine ECU.

PROBABLE CAUSES

• Malfunction of the CAN bus

• Engine ECU malfunction

• ASC-ECU malfunction

• When the ignition switch is turned to the "ON" 

position for the first time after the ASC-ECU is 
replaced.

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 diagnosis code No.C2203 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.