Mitsubishi Lancer Evolution X. Manual — part 150

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-65

STEP 14. Wiring harness check between A-05 ASC-ECU
connector terminal No. 36 and D-18 wheel speed sensor
<RL> connector terminal No. 1, and between A-05
ASC-ECU connector terminal No. 37 and D-18 wheel speed
sensor <RL> connector terminal No. 2

• Open circuit check of wheel speed sensor <RL> circuit

Q: Is the check result normal?

YES : Go to Step 15.
NO : Repair the wiring harness. Then go to Step 16.

STEP 15. Check whether the DTC is reset.
(1) Erase the DTC.
(2) 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 C1027 set?

YES : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-298

.) Then go to Step 16.

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

to Cope with Intermittent Malfunction

P.00-15

.)

STEP 16. Check whether the DTC is reset.
(1) Erase the DTC.
(2) 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 C1027 set?

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

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-66

DTC C1032: Abnormality in RR wheel speed sensor signal

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

AC708955

Connector: D-09

D-09 (B)

AH

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-67

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

ASC-ECU monitors the signals from each wheel speed sensor
while the vehicle is being driven. If any abnormality below is
detected in the sensor signals, ASC-ECU sets the relevant
diagnostic trouble code.

• Irregular change in the wheel speed sensor signal
• Wheel speed sensor signal continuously indicates higher

value than the values of other wheel speed sensors.

.

PROBABLE CAUSES

Current trouble

• Excessive gap between the wheel speed sensor and the

magnetic encoder for wheel speed detection

• Adhesion of foreign materials on the wheel speed sensor
• Adhesion of foreign materials on the magnetic encoder for

wheel speed detection

• Wheel bearing malfunction
• Malfunction of wheel speed sensor
• Damaged wiring harness and connectors
• External noise interference
• Improper installation of the wheel speed sensor
• Deformation of the magnetic encoder for wheel speed

detection

• ASC-ECU malfunction
• Disturbance of magnetization pattern for magnetic encoder

for wheel speed detection

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-68

• The number of poles on the magnetic encoder for wheel

speed detection (the number of N-pole and S-pole) is
changed.

Past trouble

• When DTC No. C102B is also set, perform the diagnosis

with a particular emphasis on the wiring harness and con-
nector failures between ASC-ECU and the wheel speed
sensor. For diagnosis procedures, refer to How to Treat
Past Trouble (GROUP 00 − How to Use Troubleshoot-

ing/Inspection Service Points

P.00-16

).

• When the diagnostic trouble code No.C102B is not set, the

following conditions may be present:

• Wheel(s) spinning
• Unstable vehicle attitude (spin)
• External noise interference
• Vehicle ran with the parking brake applied.

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 −

CAN Bus Diagnostics Table

P.54C-9

). On completion,

go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1032 set?

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

STEP 3. Scan tool diagnostic trouble code
Check if DTC No. C102B is also set.
Q: Is DTC C102B also set?

YES : Carry out the diagnosis for DTC C102B. (Refer to

P.35C-25

.)

NO : Go to Step 4.