Mitsubishi Lancer (4A9 engine). Manual — part 66

AC612705

Connector: C-137 <LHD>

C-137 (B)

AC701122

Connector: C-137 <RHD>

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-117

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.

• Do not drop or shock the G and yaw rate sen-

sor.

• When the G and yaw rate sensor is replaced,

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

P.35C-

182

• 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

and

OPERATION

• ASC-ECU supplies power to the G and yaw rate

sensor at the terminal No.1.

• The G and yaw rate sensor outputs the signal to

ASC-ECU via the special CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if any malfunction below is
found:

Code No. C2114

• When the power supply voltage applied from

ASC-ECU to the G and yaw rate sensor is not
within the standard value range <low voltage (6.5
± 0.5 V or less)>

Code No. C2115

• When the power supply voltage applied from

ASC-ECU to the G and yaw rate sensor is not
within the standard value range <high voltage
(18.0

± 1.0 V or more)>

PROBABLE CAUSES

• Damaged wiring harness and connectors

• G and yaw rate sensor malfunction

• 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 2.

NO :

Repair the CAN bus lines (Refer to GROUP
54C

− CAN Bus Diagnostics Table ). On

completion, go to Step 2.

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis code No.U0125 is set in
ASC-ECU.

Q: Is the diagnosis code No.U0125 set?

YES :

Troubleshoot for the diagnosis code (Refer

P.35C-133

). Then go to Step 3.

NO :

Go to Step 3.

STEP 3. Diagnosis code recheck

Q: Are the diagnosis codes No. C2114 or C2115 set?

YES :

Go to Step 4.

NO :

This diagnosis is complete.

STEP 4. M.U.T.-III data list
Check the following data list (Refer to

P.35C-172

• Item 08: Lateral G sensor

• Item 09: G sensor

• Item 12: Yaw rate sensor

Q: Is the check result normal?

YES :

Go to Step 12.

NO :

Go to Step 5.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-118

STEP 5. Connector check: A-58 ASC-ECU
connector, C-137 G and yaw rate sensor
connector

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Repair the defective connector.

STEP 6. Check the harness wire between C-137 G
and yaw rate sensor connector terminal No. 2, 3
and A-58 ASC-ECU connector No. 18, 19.

• Check the communication lines for open circuit

and short circuit.

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the wiring harness, and then go to
Step 13.

STEP 7. G and yaw rate sensor installation check
Check that the G and yaw rate sensor is installed
correctly.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Reinstall the G and yaw rate sensor
correctly (Refer to

P.35C-189

), and then go

to Step 13.

STEP 8. Voltage measurement at C-137 G and
yaw rate sensor connector
(1) Disconnect the C-137 G and yaw rate sensor

connector.

(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 11.

NO :

Go to Step 9.

STEP 9. Voltage measurement at A-58 ASC-ECU
connector
(1) Disconnect the ASC-ECU connector, connect the

ASC check harness (Special tool: MB991997) to
the ASC-ECU-side connector and harness-side
connector, and then measure at the special tool
connector side.

(2) Disconnect the C-137 G and yaw rate sensor

connector.

(3) Turn the ignition switch to the "ON" position.

AC606870BQ

ASC-ECU

MB991997

Check harness

A-58 ASC-ECU
harness connector

(4) Measure the voltage between the terminal No.22

and the body earth.

OK: Approximately system voltage

Q: Is the check result normal?

YES :

Go to Step 12.

NO :

Go to Step 10.

STEP 10. Wiring harness check between A-58
ASC-ECU connector terminal No.22 and C-137 G
and yaw rate sensor connector terminal No.1.

• Check the power supply circuit for short circuit.

Q: Is the check result normal?

YES :

Go to Step 12.

NO :

Repair the wiring harness between A-58
ASC-ECU connector terminal No.22 and C-
137 G and yaw rate sensor connector
terminal No.1.

STEP 11. Wiring harness check between A-58
ASC-ECU connector terminal No.29 and C-137 G
and yaw rate sensor connector terminal No.4.

• Check the earth circuit for open circuit.

Q: Is the check result normal?

YES :

Replace the G and yaw rate sensor (Refer

P.35C-189

) and then go to Step 12.

NO :

Repair the wiring harness between A-58
ASC-ECU connector terminal No.29 and C-
137 G and yaw rate sensor connector
terminal No.4.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-119

STEP 12. Check whether the diagnosis code is
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

Q: Are the diagnosis codes No.C2114 or C2115 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

), and then

go to Step 13.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 13. Check whether the diagnosis code is
reset.
(1) Erase the diagnosis code.
(2) Drive the vehicle at 20 km/h or higher.

Q: Are the diagnosis codes No.C2114 or C2115 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. C123A: Abnormality in sensor calibration

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.

• Do not drop or shock the G and yaw rate sen-

sor.

• When the steering wheel sensor is replaced,

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

P.35C-

183

• When the G and yaw rate sensor is replaced,

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

P.35C-

182

• 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

and

OPERATION
ASC-ECU stores the calibrated value of the G and
yaw rate sensor, steering wheel sensor, and brake
fluid pressure sensor.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the calibrated value
for each sensor stored in ASC-ECU is not within the
predetermined range.

• Abnormality in neutral position of the G and yaw

rate sensor

• Abnormality in neutral position of the steering

wheel sensor

• Abnormality in neutral position of the brake fluid

pressure sensor

PROBABLE CAUSES

• Improper installation of G and yaw rate sensor or

steering wheel sensor

• ASC-ECU malfunction

• External noise interference

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 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.C123A set?

YES :

Go to Step 3.

NO :

This diagnosis is complete.

STEP 3. Check other diagnosis code is set.
Check if the diagnosis code related to the G and yaw
rate sensor and the steering wheel sensor is set.

Q: Is any diagnosis code set?

YES :

Perform the diagnosis for the relevant

diagnosis code (Refer to

P.35C-16

NO :

Go to Step 4.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-120

STEP 4. G and yaw rate sensor calibration
Perform the calibration of G and yaw rate sensor
(Refer to

P.35C-182

Q: Has the calibration succeeded?

YES :

Go to Step 5.

NO :

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

P.35C-185

), and then

go to Step 8.

STEP 5. Steering wheel sensor calibration
Perform the calibration of steering wheel sensor
(Refer to

P.35C-183

Q: Has the calibration succeeded?

YES :

Go to Step 6.

NO :

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

P.35C-185

), and then

go to Step 8.

STEP 6. Brake fluid pressure sensor calibration
Perform the calibration of brake fluid pressure sensor
(Refer to

P.35C-184

Q: Has the calibration succeeded?

YES :

Go to Step 7.

NO :

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

P.35C-185

), and then

go to Step 8.

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

Q: Is diagnosis code No.C123A set?

NO :

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

P.35C-185

), and then

go to Step 8.

NO :

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.C123A set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. C1219 Abnormality in steering wheel sensor signal

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

• Do not drop or shock the G and yaw rate sen-

sor.

• When the G and yaw rate sensor is replaced,

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

P.35C-

182

• 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

and

OPERATION
Steering wheel sensor outputs the signal to ASC-
ECU via the CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if any malfunction below is
found:

• The tolerance of neutral position of steering

wheel sensor exceeds the specified range.

• Abnormality in steering wheel sensor output

value

• When abnormality is detected by comparing the