Subaru Legacy (2005 year). Manual - part 771

ABS(diag)-49

ABS (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

I:

DTC C0115 ABS WHEEL SPEED SENSOR SIGNAL MALFUNCTION IN ONE 
OF FOUR WHEELS

DTC DETECTING CONDITION:
• Defective ABS wheel speed sensor signal (noise, abnormal signal, etc.)
• Defective magnetic encoder
• When a wheel is turned freely for a long time
TROUBLE SYMPTOM:
• ABS does not operate.
• EBD does not operate.

NOTE:
Brake warning light comes on as well as ABS warning light.

11

CHECK SOURCES OF SIGNAL NOISE.
Check if the noise sources are (such as an 
antenna) installed near the sensor harness.

Are noise sources installed?

Go to step 12.

Install the noise 
sources apart from 
the sensor har-
ness.

12

CHECK ABSCM&H/U.
1) Connect all the connectors.
2) Perform clear memory mode.
3) Perform the inspection mode. <Ref. to 
ABS(diag)-25, Inspection Mode.>
4) Read the DTC.

Is the same DTC displayed?

Replace the 
ABSCM only. 
<Ref. to ABS-8, 
REPLACEMENT, 
ABS Control Mod-
ule and Hydraulic 
Control Unit 
(ABSCM&H/U).>

Go to step 13.

13

CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Perform the diag-
nosis according to 
DTC. 

It results from a 
temporary noise 
interference.

NOTE:
Though ABS warn-
ing light remains to
illuminate at this
time, it is normal.
Drive the vehicle at
more than 12 km/h
(7 MPH) in order to
make ABS warning
light go off. Be sure
to drive the vehicle
and check the
warning light goes
off.

Step

Check

Yes

No

ABS(diag)-50

ABS (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

WIRING DIAGRAM:
• LHD model

ABS00722

4

3

1

16

17

2

15

B98

R72

R2

E

1

2

15

14

6

5

R73

1

2

B6

B15

2

1

6

5

B301

1

2

FRONT ABS

WHEEL SPEED

SENSOR LH

TWISTED WIRE

FRONT ABS

WHEEL SPEED

SENSOR RH

REAR ABS

WHEEL SPEED

SENSOR LH

REAR ABS

WHEEL SPEED

SENSOR RH

TWISTED WIRE

TWISTED WIRE

TWISTED WIRE

ABSCM & H/U

R73

R72

B15

B6

B301

1 2 3 4 5 6 7 8 9 10 11

16 17 18 19 20 21 22 23 24 25 26

13

12

15

14

B98

2 3

4 5 6 7

8 9 10 11 12 13 14 15 16

1

1 2

ABS(diag)-51

ABS (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

• RHD model

ABS00723

4

3

1

16

17

2

15

B97

R72

R1

E

1

2

19

18

8

7

R73

1

2

B6

B15

R73

R72

2

1

6

5

B301

1

2

B15

B6

B301

B97

1 2 3 4 5 6 7 8 9 10 11

16 17 18 19 20 21 22 23 24 25 26

13

12

15

14

1 2 3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

FRONT ABS

WHEEL SPEED

SENSOR LH

TWISTED WIRE

FRONT ABS

WHEEL SPEED

SENSOR RH

REAR ABS

WHEEL SPEED

SENSOR LH

REAR ABS

WHEEL SPEED

SENSOR RH

TWISTED WIRE

TWISTED WIRE

TWISTED WIRE

ABSCM & H/U

1 2

ABS(diag)-52

ABS (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

1

WHETHER A WHEEL TURNED FREELY OR 
NOT.
Check if the wheels have been turned freely for 
more than one minute, such as when the vehi-
cle is jacked-up, under full-lock cornering or 
when the wheels are not in contact with road 
surface.

Did the wheels turn freely?

ABS is normal. 
Erase the memory.

NOTE:
When the wheels
turn freely for a
long time, such as
when the vehicle is
towed or jacked-
up, or when steer-
ing wheel is contin-
uously turned all
the way, this diag-
nostic trouble code
may sometimes
occur.

Go to step 2.

2

CHECK TIRE SPECIFICATIONS.
Turn the ignition switch to OFF.

Are the tire specifications cor-
rect?

Go to step 3.

Replace the tire.

3

CHECK WEAR OF TIRE.

Is the tire worn excessively?

Replace the tire.

Go to step 4.

4

CHECK TIRE INFLATION PRESSURE.

Is the tire pressure correct?

Go to step 5.

Adjust the tire 
pressure.

5

CHECK INSTALLATION OF ABS WHEEL 
SPEED SENSOR.

Is the ABS wheel speed sen-
sor installation bolt tightened 
7.5 N

⋅m (0.76 kgf-m, 5.5 ft-lb)? 

(four of them)

Go to step 6.

Tighten the ABS 
wheel speed sen-
sor installation 
bolts.

6

CHECK ABS WHEEL SPEED SENSOR SIG-
NAL.
1) Install the ABS wheel speed sensor.
2) Prepare an oscilloscope.
3) Check ABS wheel speed sensor. <Ref. to 
ABS-13, ABS WHEEL SPEED SENSOR, 
INSPECTION, Front ABS Wheel Speed Sen-
sor.>

Does the oscilloscope indicate 
the waveform pattern like 
shown in the figure when the 
tire is slowly turned? Does the 
oscilloscope indication repeat 
the waveform pattern like 
shown in the figure when the 
tire is slowly turned in equal 
speed for more one rotation?

Go to step 8.

Go to step 7.

7

CHECK ABS WHEEL SPEED SENSOR AND 
MAGNETIC ENCODER.

Is there foreign particles, 
breakage or damage in the 
pole piece of ABS wheel speed 
sensor or magnetic encoder?

Remove dirt com-
pletely. Replace 
the ABS wheel 
speed sensor or 
magnetic encoder 
as a unit with hub 
unit bearing when 
it is broken or 
damaged.

Go to step 8.

8

CHECK ABSCM&H/U.
1) Connect all the connectors.
2) Perform clear memory mode.
3) Perform the inspection mode. <Ref. to 
ABS(diag)-25, Inspection Mode.>
4) Read the DTC.

Is the same DTC displayed?

Replace the 
ABSCM only. 
<Ref. to ABS-8, 
REPLACEMENT, 
ABS Control Mod-
ule and Hydraulic 
Control Unit 
(ABSCM&H/U).>

Go to step 9.