Mitsubishi Lancer (4A9 engine). Manual - part 79

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-169

and the body earth.

OK: Approximately system voltage

Q: Is the check result normal?

YES : 

No action is necessary and testing is 

complete.

NO : 

Go to Step 8.

STEP 8. Check the fuse No.12.
Visually check for open circuit in fuse No.12.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

The short circuit may be present in the 
power supply circuit. Check the wiring 
harness between the C-211 steering wheel 
sensor connector terminal No.2 and the C-
317 ETACS-ECU connector terminal No.5, 
and repair if necessary. And then replace 
the fuse No.12.

STEP 9. Check the wiring harness between C-211 
steering wheel sensor connector terminal No.2 
and C-317 ETACS-ECU connector terminal No.5.

• Check the power supply lines (battery power sup-

ply) for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Repair the wiring harness between the C-
211 steering wheel sensor connector 
terminal No.2 and the C-317 ETACS-ECU 
connector terminal No.5.

STEP 10. M.U.T.-III other system data list
Check the input signal of IG1 relay.

•

Item No.

Item name

Normal 
condition

Item 254

IG voltage

System voltage

Turn the ignition switch to the ON position.

OK: Normal condition is displayed.

Q: Is the check result normal?

YES : 

Replace the steering wheel sensor.

NO : 

Refer to GROUP 54A - ETACS 

− Input 

Signal Procedures/Input Signal Procedure 2 
"The ignition switch (IG1) signal is not 
received." .

Inspection Procedure 14: ABS/stability control/TCL operates too frequently.

CAUTION

• If there is any problem in the CAN bus lines, 

an incorrect diagnosis code may be set. Prior 
to this diagnosis, always 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.

COMMENTS ON TROUBLE SYMPTOM

• Although the cause of the trouble cannot be 

clearly resolved since it depends on the running 
status and road surface condition, the malfunc-
tion of the hydraulic circuit may occur if any diag-
nosis code is not detected.

• If wheels and tyres other than the ones with gen-

uine specified size are mounted, the ABS/stability 
control/TCL may be activated prematurely.

• If a non-genuine braking device or non-genuine 

impact reduction device is mounted, the ABS/sta-
bility control/TCL may be activated prematurely.

PROBABLE CAUSES

• Mounting of wheels and tyres other than with 

genuine specified size

• Tyre pressure abnormality

• Tyre wear and deterioration

• Mounting of non-genuine braking device or 

impact reduction device

• Wheel alignment abnormality

• Malfunction of brake related parts

• Malfunction of the wheel speed sensor

• Malfunction of the G and yaw rate sensor

• Steering wheel sensor malfunction

• Malfunction of hydraulic unit (integrated with 

ASC-ECU)

• Malfunction of hydraulic circuit

• External radio wave noise interference

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-170

DIAGNOSIS PROCEDURE

STEP 1. Check the wheels and the tyres.
Carry out the following check.

• Size check of wheels and tyres

• Tyre wear and deterioration statuses

• Check the tyre pressure.

NOTE: For the tyre pressure, refer to the tyre pres-

sure label attached to the lower section of driver's 
side door striker.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Correct the wheels and tyres in good 
condition. Then go to Step 9.

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

P.35C-16

).

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Carry out the diagnosis for the diagnosis 
code chart (Refer to 

P.35C-16

). Then go to 

Step 9.

STEP 3. Check of brake system related 
components other than hydraulic unit (integrated 
with ABS-ECU)
At the same time with the following checks, also 
check that no parts other than the genuine parts are 
mounted.

• Brake pad check (Refer to GROUP 35A − On-

vehicle Service/Brake Pad Check ).

• Brake disc runout check (Refer to GROUP 35A − 

On-vehicle Service/Brake Disc Check ).

• Brake drag force check (Refer to GROUP 35A − 

On-vehicle Service/Brake Drag Force Check ).

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair or replace the part(s) having damage 
or other problems. Then go to Step 9.

STEP 4. Wheel alignment check
At the same time with the following checks, also 
check that no parts other than the genuine parts are 
mounted.

• Front wheel alignment check (Refer to GROUP 

33 

− On-vehicle Service/Front Wheel Alignment 

Check and Adjustment ).

• Rear wheel alignment check (Refer to GROUP 

34 

− On-vehicle Service/Rear Wheel Alignment 

Check and Adjustment ).

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair or replace the part(s) having damage 
or other problems. Then go to Step 9.

STEP 5. Wheel speed sensor check
Check that no non-genuine electronic device or no 
wiring harness of other than genuine electronic 
device is mounted near the wheel speed sensor (at 
wheel speed detection section and wiring harness 
section) (Refer to 

P.35C-188

).

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Remove the non-genuine electronic device 
or the wiring harness of non-genuine 
electronic device. Then go to Step 9.

STEP 6. M.U.T.-III data list
Check the following data list (Refer to 

P.35C-172

).

• Item 01: FL wheel speed sensor

• Item 02: FR wheel speed sensor

• Item 03: RL wheel speed sensor

• Item 04: RR wheel speed sensor

• Item 08: Lateral G-sensor

• Item 11: Steering angle sensor

• Item 12: Yaw rate sensor

Q: Is the check result normal?

YES : 

Go to Step 7.

NO (Abnormality with items 01 to 04) : 

Check the 

installation status of corresponding wheel 
speed sensor (Refer to 

P.35C-188

).

NO (Abnormality with items 08, 12) : 

Check the 

installation status of G and yaw rate sensor 
(Refer to 

P.35C-189

).

NO (Abnormality with item 11) : 

Check the 

installation status of steering wheel sensor 
(Refer to 

P.35C-190

).

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-171

STEP 7. Hydraulic unit check
Carry out the following actuator tests, and check if 
they work normally (Refer to 

P.35C-175

).

• Item No. 01: FL wheel ABS

• Item No.02: FR wheel ABS

• Item No.03: RL wheel ABS

• Item No.04: RR wheel ABS

• Item No.05: FL wheel TCL

• Item No.06: FR wheel TCL

• Item No.07: RL wheel TCL

• Item No.08: RR wheel TCL

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

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

P.35C-185

). Then go 

to Step 9.

STEP 8. ABS/stability control/TCL operation 
check

Q: Is the check result normal?

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

). Then go 

to Step 9.

STEP 9. ABS/stability control/TCL operation 
check

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Return to Step 1.

Inspection Procedure 15: ESS inoperative or improper operative

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.

COMMENTS ON TROUBLE SYMPTOM
In case of this trouble symptom, ESS operation may 
be disabled. Diagnosis code may be set by the ASC 
system using M.U.T.-III.
NOTE: Before carrying out the troubleshooting, ask 
the user and confirm the driving conditions when the 
failure has occurred.

PROBABLE CAUSES

• Low battery voltage

• Wiring harness or connector failure of CAN bus 

line

• The ASC-ECU is defective.

• Different ETACS-ECU, abnormal variant coding 

information

• Different ASC-ECU.

• Malfunction of ETACS-ECU.

DIAGNOSIS PROCEDURE

STEP 1. Hydraulic unit (integrated with ASC-
ECU) check
Check the hydraulic unit (integrated with ASC-ECU) 
part No.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

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

P.35C-185

). Then go 

to Step 2.

STEP 2. ETACS-ECU check
Check the ETACS-ECU part No.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Replace ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ). Then go to Step 3.

STEP 3. Diagnosis code check
Use M.U.T.-III to check the diagnosis code for the 
ASC system and ETACS-ECU (Refer to 

P.35C-16

 

and GROUP 54A 

− ETACS/Diagnosis code chart ).

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Carry out the diagnosis for the diagnosis 
code. (Refer to 

P.35C-16

 or GROUP 54A 

− 

ETACS/Diagnosis code chart ). Then go to 
Step 4.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-172

STEP 4. M.U.T.-III actuator test
Perform the following actuator test, and check if the 
ESS operation (Refer to 

P.35C-175

).

• Item No.10: ESS test mode

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Go to Step 5.

STEP 5. Check ETACS coding data
Refer to GROUP 00 

− Precautions before Service/

Coding List .

ESS

OK: Present

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ). Then go to Step 9.

STEP 6. Check the ASC-ECU power supply 
circuit.
Refer to 

P.35C-159

.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Carry out the diagnosis of ASC-ECU power 
supply circuit system (Refer to 

P.35C-159

). 

Then go to Step 9.

STEP 7. M.U.T.-III actuator test
Perform the following actuator test, and check if the 
ESS operation (Refer to 

P.35C-175

).

• Item No.10: ESS test mode

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ). Then go to Step 8.

STEP 8. M.U.T.-III actuator test
Perform the following actuator test, and check if the 
ESS operation (Refer to 

P.35C-175

).

• Item No.10: ESS test mode

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

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

P.35C-185

). Then go 

to Step 9.

STEP 9. M.U.T.-III actuator test
Perform the following actuator test, and check if the 
ESS operation (Refer to 

P.35C-175

).

• Item No.10: ESS test mode

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Return to Step 1.

Inspection procedure 16: The initial check sound of hydraulic unit is loud.

CAUTION

When installing brake tube, match the axial 

centre of flare nut and brake tube with the centre 
of hole at the hydraulic unit side, and check that 
the fluid does not leak.
COMMENT ON TROUBLE SYMPTOM
The operation sound may be decreased by reducing 
the load at the rubber mount portion of the brake 
tube and hydraulic unit. 

PROBABLE CAUSES

• Improper installation of the hydraulic unit

• Improper installation of the brake tube

DIAGNOSIS PROCEDURE

DRIVING CHECK
(1) Turn the ignition switch from the "LOCK" (OFF) 

position to the "ON" position.

(2) When vehicle speed reaches 10 km/h, check the 

operating sound volume and compare it with that 
of the same model.

OK: The operating sound is the same vol-
ume or less by comparing with that of the 
same model.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Carry out adjustment for hydraulic unit 
installation. (Refer to 

P.35C-179

).

DATA LIST REFERENCE TABLE

M1355001500960

The following items of ECU input data can be read 
using M.U.T.-III.