Mitsubishi Lancer Evolution X. Manual — part 172

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-153

STEP 15. Measure the voltage at C-48 stoplight switch
connector.
(1) Disconnect C-48 stoplight switch connector, and measure

the voltage at harness connector side.

(2) Measure the voltage between the terminal No.2 and the

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 16.
NO : An open circuit may be present in the wiring harness

between C-304 ETACS-ECU connector terminal No.
1 and C-48 stoplight switch connector terminal No. 2.
Repair the wiring harness.

STEP 16. Connector check: C-43 joint connector
Q: Is the check result normal?

YES : Go to Step 17.
NO : Repair the damaged connector.

STEP 17. Voltage measurement at C-43 joint connector

CAUTION

Measure while the brake pedal is depressed.
(1) Disconnect the connector, and measure at the wiring

harness side.

(2) Measure the voltage between the terminal No.2 and the

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 18.
NO : An open circuit may be present in the wiring harness

between C-43 joint connector terminal No.2 and C-48
stoplight switch connector terminal No.1. Repair the
wiring harness.

STEP 18. Connector check: C-312 ETACS-ECU connector
Q: Is the check result normal?

YES : Go to Step 19.
NO : Repair the damaged connector.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-154

STEP 19. Measure the voltage at the C-312 ETACS-ECU
connector.
(1) Measure by backprobing without disconnecting the

connector.

(2) Measure the voltage between the terminal No.16 and the

body ground.

OK:

When the brake pedal is released: 0 V - 5V (pulse)
When the brake pedal is depressed: Approxi-

mately battery positive voltage

Q: Is the check result normal?

YES : Go to Step 22.
NO : Go to Step 20.

STEP 20. Check the wiring harness between C-312
ETACS-ECU connector terminal No.16 and C-48 stoplight
switch connector terminal No.1

• Check the signal line for open circuit.

Q: Is the check result normal?

YES : Go to Step 21.
NO : Replace the wiring harness.

STEP 21. Diagnostic trouble code recheck
Q: Is diagnostic trouble code No.C1000 set?

YES : Replace the hydraulic unit (ASC-ECU) (Refer to

P.35C-298

). Then go to Step 23.

NO : Intermittent malfunction (Refer to GROUP 00 − How to

Cope with Intermittent Malfunction

P.00-15

STEP 22. Check whether the DTC is reset.
Q: Is DTC 1000 set?

YES : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-298

.) Then go to Step 23.

NO : Intermittent malfunction. (Refer to GROUP 00 − How

to Cope with Intermittent Malfunction

P.00-15

STEP 23. Check whether the DTC is reset.
Q: Is DTC 1000 set?

YES : Return to Step 1.
NO : The procedure is complete.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-155

DTC C123B: Prolonged operation of ASC

CAUTION

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

rect diagnostic trouble code may be set. Prior to this
diagnosis, diagnose the CAN bus lines.

• Whenever the ECU is replaced, ensure that the CAN

bus lines are normal.

• When the steering wheel sensor is replaced or

re-installed, always perform the calibration to make
ASC-ECU learn the neutral point. (Refer to

P.35C-289

• Do not drop the G and yaw rate sensor or subject it to a

shock.

• When the G and yaw rate sensor is replaced, always

perform the calibration to make ASC-ECU learn the
neutral point. (Refer to

P.35C-287

• When the hydraulic unit (integrated with ASC-ECU) is

replaced, always perform the calibration of steering
wheel sensor, G and yaw rate sensor, brake fluid pres-
sure sensor, cut valve, and inlet valve.(Refer to

CIRCUIT OPERATION

ASC-ECU controls ASC by calculating the data sent from the
wheel speed sensor, steering wheel sensor, and G and yaw
rate sensor.

DTC SET CONDITIONS

This diagnostic trouble code is set when ASC control is oper-
ated for a prolonged period.
NOTE: This diagnostic trouble code may be set when the vehi-
cle runs on a slippery or rough road, or when the vehicle per-
forms a steady state cornering.

PROBABLE CAUSES

• Steering wheel sensor malfunction
• G and yaw rate sensor malfunction
• Improper installation of steering wheel sensor or G and yaw

rate sensor

• ASC-ECU malfunction
• Different steering wheel
• Wheel alignment not performed

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827 M.U.T.-III USB Cable
• MB991910 M.U.T.-III Main Harness A

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-156

STEP 1. Using scan tool MB991958, diagnose the CAN bus
lines.
Using scan tool MB991958, 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 −

Troubleshooting

P.54C-15

.) After repairing the CAN

bus line, go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C123B set?

YES : Go to Step 3.
NO : This diagnosis is complete.

STEP 3. Scan tool diagnostic trouble code
Check that DTCs C100A, C1015, C1020, C102B, C1011,
C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041,
C1042, C1043, C1044, C1219, C2205, C123C, and C2204 are
also set.
Q: Are DTCs C100A, C1015, C1020, C102B, C1011, C101C,

C1027, C1032, C1014, C101F, C102A, C1035, C1041,
C1042, C1043, C1044, C1219, C2205, C123C, and C2204
also set?
YES : Carry out the diagnosis for the diagnostic trouble

code that is set. (Refer to

P.35C-22

.) Then go to Step

10.

NO : Go to Step 4.

STEP 4. Check of G and yaw rate sensor installation status
Check that the G and yaw rate sensor is installed correctly.
Q: Is the check result normal?

YES : After checking the G and yaw rate sensor, perform

the calibration of the G and yaw rate sensor to make
ASC-ECU relearn the neutral point.(Refer to

P.35C-287

.) Then go to Step 5.

NO : Reinstall the G and yaw rate sensor correctly. (Refer

P.35C-304

.) Then go to Step 10.

STEP 5. Scan tool service data
Check the following service data. (Refer to

P.35C-276

• Item 08: Lateral G sensor
• Item 09: G sensor
• Item 12: Yaw rate sensor

Q: Is the check result normal?

YES : Go to Step 6.
NO : Replace the G and yaw rate sensor. (Refer to