Mitsubishi Lancer (4A9 engine). Manual — part 59

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-89

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

AC606869FS

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) Disconnect the fusible link No.26.
(3) Measure the resistance between the terminal

No.1 and the body earth.

OK: No continuity

Q: Is the check result normal?

YES :

Replace the fusible link No.26. Then go to

Step 11.

NO :

The short circuit may be present in the
power supply circuit. Repair the wiring
harness between the A-58 ASC-ECU
connector terminal No.1 and the fusible link
No.26, and then replace the fusible link
No.26. Then go to Step 11.

STEP 8. Voltage measurement at the A-58 ASC-
ECU connector

AC606869DI

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) 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 :

The open circuit may be present in the
power supply circuit. Repair the wiring
harness between the A-58 ASC-ECU
connector terminal No.1 and the fusible link
No.26. Then go to Step 11.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-90

STEP 9. 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) Measure the 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 10.

NO :

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. Then 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 the diagnosis code No. C1073 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

). Then go

to Step 11.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 11. 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 the diagnosis code No. C1073 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-91

Code No. C2116 Low or high power supply voltage in pump motor

Solenoid Valve and Motor Power Source Circuit

MOTOR
POWER
SOURCE

SOLENOID
VALVE
POWER
SOURCE

ASC-ECU

SOLENOID
VALVE
POWER
SOURCE

MOTOR POWER
SOURCE

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

SOLENOID VALVE

HYDRAULIC UNIT

MOTOR

FUSIBLE
LINK

27

FUSIBLE
LINK

26

ACB02566

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-92

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

• ASC-ECU contains the power supply circuit (ter-

minal No.1) for the pump motor. The pump motor
is energised by the motor switch, which is incor-
porated in ASC-ECU.

• The pump motor switch, which is incorporated in

ASC-ECU, is always off unless the motor sole-
noid valve check is activated when the vehicle is
started.

• ASC-ECU activates the pump motor by turning

on the ECU built-in pump motor switch.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis codes will be set under the cases
below:

• When the power supply voltage of the pump

motor, which is not in operation, is abnormally low
for a prolonged period

• When the power supply voltage of the pump

motor, which is not in operation, is abnormally
high for a prolonged period

PROBABLE CAUSES

Current trouble

• Fusible link malfunction

• Damaged wiring harness and connectors

• Abnormality in battery or alternator

• ASC-ECU malfunction

Past trouble

• Carry out diagnosis with particular emphasis on

wiring harness and connector failures between
the power supply circuit (A-58 ASC-ECU connec-
tor terminal No.1) to the ASC-ECU motor and the
earth circuit (A-58 ASC-ECU connector terminal
No.16 and 47). For diagnosis procedures, refer to
How to treat past trouble (GROUP 00

− How to

Use Troubleshooting/How to Treat Past Trouble ).

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. C2116 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 4.

NO :

Replace the battery. Then go to Step 11.

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 :

Go to Step 5.

NO :

Repair or replace the charging system
component(s). Then go to Step 11.

STEP 5. Connector check: A-58 ASC-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Repair the defective connector. Then go to
Step 11.

STEP 6. Fusible link check: Check the fusible link
No.26.
Visually check for open circuit in the fusible link
No.26.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Go to Step 7.