Mitsubishi Lancer (4A9 engine). Manual — part 78

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-165

STEP 19. Resistance measurement at A-58 ASC-
ECU connector
(1) Disconnect the C-315 ETACS-ECU connector.

AC606869HS

ASC-ECU

MB991997

Check harness

A-58 ASC-ECU
harness connector

Connector: C-315
(harness side)

(2) Disconnect the A-58 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.

(3) Measure the resistance between the A-58 ASC-

ECU connector terminal No.2 and the C-315
ETACS-ECU connector terminal No.4.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 20.

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.2 and the C-315
ETACS-ECU connector terminal No.4. Then
go to Step 24.

STEP 20. Measure the voltage at the C-317
ETACS-ECU connector.
(1) Measure by backprobing without disconnecting

the connector.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the terminal No.6

and the body earth.

OK: Approximately battery voltage

Q: Is the check result normal?

YES :

Go to Step 22.

NO :

Go to Step 21.

STEP 21. Resistance measurement at C-317
ETACS-ECU connector and the C-212 ignition
switch connector
(1) Disconnect the C-317 ETACS-ECU connector

and C-212 ignition switch connector, and then
measure the resistance at the harness connector
side.

(2) Measure the resistance between the C-317

ETACS-ECU connector terminal No.6 and C-212
ignition switch connector terminal No.2.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Diagnose the ignition switch (Refer to ).

NO :

The open circuit may be present in the
power supply circuit. Repair the wiring
harness between the C-317 ETACS-ECU
connector terminal No.6 and C-212 ignition
switch connector terminal No.2. Then go to
Step 24.

STEP 22. 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

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-166

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 23.

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.

STEP 23. Retest the system.

Q: Is the communication with M.U.T.-III possible?

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 24.

STEP 24. Retest the system.

Q: Is the communication with M.U.T.-III possible?

YES :

This diagnosis is complete.

NO :

Return to Step 1.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-167

Inspection Procedure 13: Steering wheel sensor power supply circuit system

Steering Wheel Sensor Power Source Circuit

STEERING WHEEL SENSOR

IG1
RELAY

<PETROL>

FUSIBLE
LINK

34

<DIESEL>

FUSIBLE
LINK

44

ETACS-
ECU

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

ACB02570

AC612716 BE

Connectors: C-211 <RHD>

C-211

AC612708 BB

Connectors: C-211 <LHD>

C-211

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-168

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 steering wheel sensor is replaced,

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

P.35C-

183

).

OPERATION

• Steering wheel sensor contains the power supply

circuit (terminal No.2) for Steering wheel sensor.
The power is supplied from the ETACS-ECU (ter-
minal No.5). The power is supplied from the fusi-
ble link No.34 <PETROL> or fusible link No.44
<DIESEL> through the multi-purpose fuse No.12.

• When malfunction occurs in Steering wheel sen-

sor power supply, the communication with
M.U.T.-III becomes unavailable.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• Fuse and fusible link malfunction

• Improper tightening of battery terminal

• Battery failure

• Charging system failed

• Steering wheel sensor malfunction

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-211 steering wheel
sensor connector

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the damaged connector.

STEP 2. Resistance measurement at C-211
steering wheel sensor connector.
(1) Disconnect C-211 steering wheel sensor

connector and measure the resistance available
at the wiring harness side of the connector.

(2) Check the continuity between C-211 steering

wheel sensor connector terminal No.5 and body
earth.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Go to Step 3.

STEP 3. Check the wiring harness between C-211
steering wheel sensor connector terminal No.5
and the body earth.

• Check the earth wires for open circuit.

Q: Is the check result normal?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

use Troubleshooting/inspection Service
Points

− How to Cope with Intermittent

Malfunction ).

NO :

Repair the wiring harness.

STEP 4. Connector check: C-309 ETACS-ECU
connector, C-317 ETACS-ECU connector

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Repair the damaged connector.

STEP 5. Voltage measurement at C-309 ETACS-
ECU connector
(1) Disconnect C-309 ETACS-ECU connector and

measure the voltage available at the wiring
harness side of the connector.

(2) Measure the voltage between C-309 ETACS-

ECU connector terminal No.1 and body earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Go to Step 6.

STEP 6. Check the wiring harness between
fusible link No. 34 <PETROL> or No. 44
<DIESEL> and C-309 ETACS-ECU connector
terminal No.1.

• Check the power supply lines (battery power sup-

ply) for open circuit and short circuit.

Q: Is the check result normal?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

use Troubleshooting/How to Cope with
Intermittent Malfunctions ).

NO :

Repair the wiring harness.

STEP 7. Measure the voltage at the C-211
steering wheel sensor connector.
(1) Disconnect C-211 steering wheel sensor

connector and measure the voltage at the wiring
harness side of the connector.

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