Mitsubishi Lancer Evolution X. Manual - part 162

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-113

STEP 13. Check of wheel speed sensor installation status
Check the installation status of wheel speed sensor <RL> (dis-
connection of wheel speed sensor, looseness of mounting bolt, 
etc.).
Q: Is the check result normal?

YES : Go to Step 14.
NO :  Reinstall the wheel speed sensor <RL> correctly. 

(Refer to 

P.35C-300

.) Then go to Step 17.

STEP 14. Wheel bearing looseness check
NOTE: 

.

•

Wheel bearing looseness may increase the gap between 
the wheel speed sensor and the wheel speed detection 
magnet encoder.

•

Check the wheel bearing <RL> for looseness. (Refer to 
GROUP 27 

−

 On-vehicle Service 

P.27-32

.)

Q: Is the check result normal?

YES : Go to Step 15.
NO :  Replace the rear wheel hub assembly. (Refer to 

GROUP 27 − Rear Axle Hub Assembly 

P.27-35

.)

STEP 15. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or defor-
mation.
Q: Is the check result normal?

YES : Go to Step 16.
NO (Adhesion of foreign materials) : Clean the encoder 

so as not to disturb the magnetization pattern on the 
encoder while taking care of the magnet, magnetic 
substance, and magnetic attraction.

NO (Deformation) : Replace the rear wheel hub assembly. 

(Refer to GROUP 27 − Rear Axle Hub Assembly 

P.27-35

.)

STEP 16. Check whether the DTC is reset.
Drive the vehicle at 12mph (20 km/h) or more.
NOTE: The ABS warning light does not turn OFF in some 
cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1048 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 17.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

AC608248AB

Magnetic
encoder

Rear Wheel
bearing

Rear wheel
hub
assembly

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-114

STEP 17. Check whether the DTC is reset.
Drive the vehicle at 12mph (20 km/h) or more.
NOTE: The ABS warning light does not turn OFF in some 
cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1048 set?

YES : Return to Step 1.
NO :  This diagnosis is complete.

DTC C1049: RR wheel speed sensor control phase time exceeded

ASC-ECU

(LH)

(LH)

(RH)

(RH)

FRONT WHEEL SPEED SENSOR

REAR WHEEL SPEED SENSOR

Wheel Speed Sensor Circuit

AC804587

AC708948

Connector: A-05

A-05 (B)

AB

AC708950

Connector: C-47

AE

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-115

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

• Each wheel speed detecting section is a kind of a pulse 

generator. It consists of the encoder (plate on which the 
north and south pole of magnet are arranged alternately) for 
detecting the wheel speed, which rotates at the same speed 
of the wheels, and the wheel speed sensor. This detecting 
section outputs the frequency pulse signals in proportion to 
the wheel speed.

• The pulse signals generated by the wheel speed detecting 

section are sent to ASC-ECU. ASC-ECU uses the fre-
quency of the pulse signals to determine the wheel speed.

.

DTC SET CONDITIONS

This diagnostic trouble code is set if any malfunction below is 
detected.

• When the brake fluid pressure is decreased for a long time.
• When the brake fluid pressure is held for a long time.

NOTE: ASC controls the vehicle based on the wheel speed sig-
nal. When the brake fluid pressure is decreased or held for an 
abnormally long time, the wheel speed sensor signal may have 
a problem.

.

PROBABLE CAUSES

• Damaged wiring harness and connectors
• External noise interference
• Malfunction of wheel speed sensor
• ABS-ECU malfunction

AC708955

Connector: D-09

D-09 (B)

AH

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-116

• Excessive gap between the wheel speed sensor and the 

wheel speed detection encoder

• Adhesion of foreign materials on the wheel speed sensor
• Adhesion of foreign materials on the wheel speed detection 

encoder

• Wheel bearing malfunction
• Improper installation of the wheel speed sensor
• Deformation of the wheel speed detection encoder
• Disturbance of magnetization pattern for wheel speed 

detection encoder

• Missing teeth of the wheel speed detection encoder

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 C1049 set?

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

STEP 3. Scan tool diagnostic trouble code
Check whether DTC No. C102B, C1032, C1035, and C1044 
are simultaneously set.
Q: Are DTC C102B, C1032, C1035 and C1044 also set?

YES : Carry out the diagnosis for the diagnostic trouble 

codes that are set, and then go to Step 5.

NO :  Go to Step 4.

STEP 4. Scan tool service data
Check the following service data. (Refer to 

P.35C-276

.)

• Item No.04: RR wheel speed sensor

Q: Is the check result normal?

YES : Go to Step 16.
NO :  Go to Step 5.