Mitsubishi Lancer Evolution X. Manual - part 169

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-141

STEP 5. Stoplight switch continuity check
(1) Remove the stoplight switch. (Refer to GROUP 35A − Brake 

Pedal 

P.35A-24

.)

(2) Connect the circuit tester (Ω range) to the stoplight switch 

connector terminal Nos. 1 and 2.

(3) When continuity does not exist with the plunger pressed 

from the outer case end face by the dimension shown in the 
figure, and when continuity exists with the plunger released, 
the switch is in good condition.

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Replace the stoplight switch. (Refer to GROUP 35A − 

Brake Pedal 

P.35A-24

.) Then go to Step 9.

STEP 6. Brake drag check
Check the brake drag force. (Refer to GROUP 35A − On-vehicle 

Service 

P.35A-23

.)

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Adjust the brake drag, and then go to Step 9.

STEP 7. Brake booster check
Refer to GROUP 35A − On-vehicle Service 

P.35A-15

.

Q: Is the check result normal?

YES : Go to Step 8.
NO :  Replace the brake booster. (Refer to GROUP 35A − 

Master Cylinder Assembly and Brake Booster 

P.35A-26

.) Then go to Step 9.

STEP 8. Check whether the DTC is reset.
Q: Is DTC C121E set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 9.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

AC901847AB

No continuity

Continuity

4.0 ± 0.5 mm 
(0.16 ± 0.02 in)

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-142

STEP 9. Check whether the DTC is reset.
Q: Is DTC C121E set?

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

DTC C2000: Abnormality in wheel fluid pressure sensor circuit

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 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 

P.35C-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

CIRCUIT OPERATION

The wheel cylinder pressure sensor is integrated into the 
hydraulic unit. It converts the signal of brake fluid pressure in 
wheel cylinder of each wheel to the voltage value, then outputs 
the value to ASC-ECU.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the voltage value, 
which was converted from the signal of brake fluid pressure in 
wheel cylinder of each wheel and sent by the wheel cylinder 
pressure sensor to ASC-ECU, is outside the standard range.

.

PROBABLE CAUSES

• Damaged wiring harness and connectors
• Malfunction of hydraulic unit (with built-in wheel cylinder 

pressure sensor)

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

• MB991997: ASC check harness

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-143

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 C2000 set?

YES : Go to Step 3.
NO :  The procedure is complete.

STEP 3. Check whether the DTC is reset.
Q: Is DTC C2000 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 4.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 4. Check whether the DTC is reset.
Q: Is DTC C2000 set?

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

DTC C2001: Abnormality in wheel fluid pressure sensor output signal

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 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 

P.35C-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

CIRCUIT OPERATION

• The wheel cylinder pressure sensor is integrated into the 

hydraulic unit. It converts the signal of brake fluid pressure 
in wheel cylinder of each wheel to the voltage value, then 
outputs the value to ASC-ECU.

• The wheel cylinder pressure sensor contains the following 

two signal output sections: Fluid pressure signal output sec-
tion and fluid pressure and temperature signal output sec-
tion.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-144

.

DTC SET CONDITIONS

This diagnostic trouble codes will be set under the cases 
below:

• The pressure sensor offset is outside the specified range. 

(Pressure is generated at all times)

• The estimated pressure sensor temperature is not normal.

.

PROBABLE CAUSES

• Damaged wiring harness and connectors
• Incorrect adjustment of brake pedal height
• Master cylinder malfunction
• Brake booster malfunction
• Incorrect installation position of stoplight switch
• Malfunction of the stoplight switch
• Brake drag
• Malfunction of the ASC-ECU

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

• MB991997: ASC check harness

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 C2001 set?

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

STEP 3. Check for diagnostic trouble codes of other 
systems
Check if the diagnostic trouble code No. C121E is set in 
ASC-ECU.
Q: Is the check result normal?

YES : Go to Step 4.
NO :  Carry out the diagnosis for the diagnostic trouble code 

No. C121E. (Refer to 

P.35C-139

.)