Mitsubishi Lancer (4A9 engine). Manual - part 68

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-125

STEP 2. Diagnosis code recheck after resetting 
CAN bus lines

Q: Is diagnosis code No.C2003 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 whether any coding-related 
diagnosis code is set by ETACS-ECU.

Q: Is the diagnosis code set?

YES : 

Troubleshoot for the relevant diagnosis 

code.

NO : 

Go to Step 4.

STEP 4. Check part number of ASC-ECU
Check the part number of ASC-ECU.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

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

P.35C-185

). Then go 

to Step 8.

STEP 5. ETACS-ECU coding data check
Refer to GROUP 00 

− Precautions before Service/

Coding List .

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace the ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ).

STEP 6. Check part number of ETACS-ECU
Check the part number of ETACS-ECU.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Replace the ETACS-ECU (Refer to GROUP 
54A 

− ETACS-ECU ).

STEP 7. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C2003 set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 8.

NO : 

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

− How to 

Use Troubleshooting/How to Cope with 
Intermittent Malfunctions ).

STEP 8. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C2003 set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-126

Code No. C1608 Implausible diagnosis data

Solenoid Valve, Motor and ASC-ECU Power Source Circuit

SOLENOID 
VALVE 
POWER 
SOURCE

MOTOR 
POWER 
SOURCE

ETACS-
ECU

ASC-ECU

POWER 
SOURCE

POWER 
SOURCE

IG1 
RELAY

IGNITION SWITCH

<PETROL>

FUSIBLE 
LINK

34

<DIESEL>

FUSIBLE 
LINK

44

Wire colour code 
B : Black     LG : Light green     G : Green 
L : Blue     W : White     Y : Yellow 
SB : Sky blue     BR : Brown     O : Orange 
GR : Grey     R : Red     P : Pink 
V : Violet     PU : Purple     SI : Silver

FUSIBLE 
LINK

26

FUSIBLE 
LINK

27

ACB02568

AC612691

AO

Connector: A-58 <LHD>

A-58 (B)

AC701238 AF

Connector: A-58 <RHD>

A-58 (B)

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-127

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
The ASC-ECU stores diagnosis codes and failure 
information in the EEPROM

*

.

ASC-ECU (EEPROM

*

)contains the power supply cir-

cuit (terminal No.2). 
NOTE: 

*

:EEPROM (Electrical Erasable and Pro-

grammable ROM)

DIAGNOSIS CODE SET CONDITIONS

• This diagnosis code is set when the failure infor-

mation stored in the EEPROM is not reliable. The 
failure information stored in the past is not output, 
and only this diagnosis code is set.

• This diagnosis code may occur when ASC-ECU 

power supply shutdown or drop while ASC-ECU 
is writing a data to the EEPROM.

PROBABLE CAUSES

• Disconnection of the ASC-ECU connector or the 

battery terminal when the ignition switch is ON

• Loose battery terminal

• Abnormality in battery

• Damaged wiring harness and connectors

• 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 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. C1608 set?

YES : 

Go to Step 3.

NO : 

The procedure 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 : 

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 charging system in good condition?

YES : 

Replace the battery. Then go to Step 9.

NO : 

Repair or replace the charging system 
component(s).

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-128

STEP 5. Voltage measurement at the A-58 ASC-
ECU connector

AC606869 HT

ASC-ECU

MB991997

Check harness

A-58 ASC-ECU
harness connector

(1) Disconnect the ASC-ECU connector, connect 

special tool ASC check harness (MB991997) to 
the harness-side connector, and then measure 
the voltage at the special tool connector side.
NOTE: Do not connect the special tool ASC 
check harness (MB991997) to ASC-ECU.

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

and the body earth.

OK: Approximately system voltage

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

STEP 6. Connector check: A-58 ASC-ECU 
connector

Q: Is the check result normal?

YES : 

The open or short circuit may be present in 

the power supply circuit. Repair the wiring 
harness between the A-58 ASC-ECU 
connector terminal No.2 and the fuse No.17.

NO  : 

Repair the defective connector.

STEP 7. Resistance measurement at A-58 ASC-
ECU connector

AC606869DJ

ASC-ECU

MB991997

Check harness

A-58 ASC-ECU
harness connector

(1) Disconnect the ASC-ECU connector, connect 

special tool ASC check harness (MB991997) to 
the harness-side connector, and then measure 
the resistance at the special tool connector side.
NOTE: Do not connect the special tool ASC 
check harness (MB991997) to ASC-ECU.

(2) Resistance between the terminal No.16 and the 

body earth, and between the terminal No.47 and 
the body earth.

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Go to Step 8.

STEP 8. Connector check: A-58 ASC-ECU 
connector

Q: Is the check result normal?

YES : 

An open circuit may be present in the earth 

circuit. Repair the wiring harness between 
the A-58 ASC-ECU connector terminal 
No.16 and the body earth, and between the 
A-58 ASC-ECU connector terminal No.47 
and the body earth.

NO  : 

Repair the defective connector.

STEP 9. Check whether the diagnosis code is 
reset.
(1) Erase the diagnosis code.