Mitsubishi Lancer (4A9 engine). Manual - part 73

AC612705

Connector: C-01 <LHD>

BK

AC701122 BN

Connectors: C-01, C-16 <RHD>

C-01

C-16

AC612706

Connector: C-16 <LHD>

AO

AC612707

AH

Connector: C-116 <LHD>

C-116 (B)

AC701089

Connector: C-116 <RHD>

C-116 (B)

AF

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-145

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.

OPERATION

• When the parking brake switch is turned ON, the 

combination meter terminal No.4 is earthed, and 
the brake warning lamp illuminates.

• When reduction of the brake fluid amount is 

detected, the brake fluid level switch is turned 
from ON to OFF. ETACS-ECU monitors the brake 
fluid level switch, and instructs the combination 
meter via the CAN bus line to illuminate the brake 
warning lamp.

PROBABLE CAUSES

• The brake pad thickness is at the limit value or 

less.

• The brake fluid amount is at the "LOWER" level 

or lower.

• Poor adjustment of the parking brake lever

• Damaged wiring harness and connectors

• Parking brake switch malfunction

• Malfunction of brake fluid level switch

• Combination meter malfunction

• Malfunction of ETACS-ECU

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 ).

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check that the diagnosis code is set 
in the combination meter and ETACS-ECU.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis for the diagnosis 

code.

NO : 

Go to Step 3.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-146

STEP 3. Brake fluid level check
Check that the brake fluid is filled up to the "MIN" 
level or higher.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Go to Step 4.

STEP 4. Brake pad check
Refer to GROUP 35A 

− On-vehicle Service, Brake 

Pad Check .

Q: Is the check result normal?

YES : 

Fill the brake fluid up to the "MAX" level. 

Then go to Step 17.

NO : 

Replace the brake pad (Refer to GROUP 
35A 

− On-vehicle Service/Brake Pad 

Replacement  <Except 4B11>,  <4B11>). 
Then go to Step 17.

STEP 5. Brake fluid level switch check
Refer to GROUP 35A 

− On-vehicle Service/Brake 

Fluid Level Switch Check .

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace the reservoir tank assembly (Refer 
to GROUP 35A 

− Master Cylinder Assembly 

and Brake Booster Assembly  <Except 
4B11>,  <4B11>). Then go to Step 17.

STEP 6. Connector check: A-07 brake fluid level 
switch connector, C-312 ETACS-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the damaged connector.

STEP 7. Measure the voltage at A-07 brake fluid 
level switch connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the terminal No. 1 

and the body earth.

OK: Approximately system voltage

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Go to Step 8.

STEP 8. Measure the voltage at the C-312 ETACS-
ECU connector.

CAUTION

With the C-312 ETACS-ECU connector kept con-
nected, disconnect the A-07 brake fluid level 
switch connector.
(1) Turn the ignition switch to the ON position.
(2) Measure the voltage between terminal No. 1 and 

the body earth by backprobing.

OK: Approximately system voltage

Q: Is the check result normal?

YES : 

Check the wiring harness between the C-

312 ETACS-ECU connector terminal No. 1 
and the A-07 brake fluid level switch 
connector terminal No. 1.

NO : 

Replace the ETACS-ECU. (Refer to 
GROUP 54A 

− ETACS .) Then go to Step 

17.

STEP 9. Wiring harness check: between A-07 
brake fluid level switch connector and body earth
Check for open circuit in the harness wire between 
A-07 brake fluid level switch connector terminal No. 2 
and body earth.

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Repair the wiring harness.

STEP 10. Parking brake lever stroke check
Refer to GROUP 36 

− On-vehicle Service/Parking 

Brake Lever Stroke Check and Adjustment .

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Adjust the parking brake lever stroke. (Refer 
to GROUP 36 

− On-vehicle Service/Parking 

Brake Lever Stroke Check and Adjustment 
.) Then go to Step 17.

STEP 11. Parking brake switch check
Refer to GROUP 36 

− On-vehicle Service/Parking 

Brake Switch Check .

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Replace the parking brake switch. (Refer to 
GROUP 36 

− Parking Brake Lever .) Then 

go to Step 17.

STEP 12. Connector check: C-116 parking brake 
switch connector

Q: Is the check result normal?

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-147

YES : 

Go to Step 13.

NO : 

Repair the damaged connector.

STEP 13. Measure the voltage at C-116 parking 
brake switch connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the terminal No. 1 

and the body earth.

OK: Approximately system voltage

Q: Is the check result normal?

YES : 

Go to Step 16.

NO : 

Go to Step 14.

STEP 14. Connector check: C-01 combination 
meter connector, C-16 intermediate connector

Q: Is the check result normal?

YES : 

Go to Step 15.

NO : 

Repair the damaged connector.

STEP 15. check the wiring harness between the 
C-01 combination meter connector terminal No. 4 
and the C-116 parking brake switch connector 
terminal No. 1.

• Check for short circuit.

Q: Is the check result normal?

YES : 

Go to Step 16

NO : 

Repair the wiring harness.

STEP 16. Retest the system.

Q: Does the brake warning lamp turn ON and OFF 

normally according to the parking brake lever 
operation?
YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use Troubleshooting/How to 

Cope with Intermittent Malfunctions .)

NO : 

Replace the combination meter assembly. 
(Refer to GROUP 54A 

− Combination Meter 

.) Then go to Step 17.

STEP 17. Retest the system.

Q: Does the brake warning lamp turn ON and OFF 

normally according to the parking brake lever 
operation?
YES : 

This diagnosis is complete.

NO : 

Return to Step 1.

Inspection Procedure 4: ABS warning lamp does not illuminate when ignition switch is turned to the 
ON position (engine stopped).

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 ).

• 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

).

OPERATION

• ASC-ECU sends the illumination request signal 

of the ABS warning lamp to the combination 
meter through ETACS-ECU via CAN communica-
tion.

• ASC-ECU illuminates the ABS warning lamp via 

ETACS-ECU for approximately 3 seconds for 
valve check with the ignition switch turned to the 
ON position.

COMMENTS ON TROUBLE SYMPTOM
This may be caused by faults in the CAN bus line, 
ETACS-ECU, combination meter or ASC-ECU.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• Malfunction of ETACS-ECU

• Combination meter malfunction

• ASC-ECU malfunction

• Malfunction of coding data for ETACS-ECU

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-148

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 .)

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check the diagnosis code for the 
ASC system. (Refer to 

P.35C-16

.)

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis for the diagnosis 

code. (Refer to 

P.35C-16

.)

NO : 

Go to Step 3.

STEP 3. Actuator test
Perform the actuator test No. 07 of the combination 
meter system, and check if the ABS warning lamp 
illuminates (Refer to GROUP 54A 

− Combination 

Meter/Actuator Test Table ).

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Diagnose the combination meter. (Refer to 
GROUP 54A 

− Combination Meter/Trouble 

Symptom Chart .) Then go to Step 8.

STEP 4. ETACS-ECU coding data check
Use M.U.T.-III to check if coding data stored in 
ETACS-ECU is normal. (Refer to GROUP 00 

− Pre-

cautions 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 8.

STEP 5. M.U.T.-III diagnosis code for other 
systems
Using M.U.T.-III, check that the diagnosis code 
No.U0141 is set by the combination meter system.

Q: Is the diagnosis code set?

YES : 

Diagnose the combination meter. (Refer to 

GROUP 54A 

− Combination Meter/

Troubleshooting .) Then go to Step 8.

NO : 

Go to Step 6.

STEP 6. M.U.T.-III diagnosis code for other 
systems
Using M.U.T.-III, check that the diagnosis code 
No.U0121 is set by the ETACS system.

Q: Is the diagnosis code set?

YES : 

Troubleshoot the ETACS-ECU (Refer to 

GROUP 54A 

− ETACS/Troubleshooting ), 

and then go to Step 8.

NO : 

Go to Step 7.

STEP 7. Retest the system.

Q: Does the ABS warning lamp turn ON and OFF 

normally?
YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use Troubleshooting/How to 

Cope with Intermittent Malfunctions .)

NO : 

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

P.35C-185

), and then 

go to Step 8.

STEP 8. Retest the system.

Q: Does the ABS warning lamp turn ON and OFF 

normally?
YES : 

This diagnosis is complete.

NO : 

Return to Step 1.