Subaru Legacy III (2000-2003 year). Manual - part 766

VDC-100

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

AJ:DTC 51 ABNORMAL VALVE RELAY

DIAGNOSIS:
• Faulty valve relay

NOTE:
When DTC 74 ABNORMAL PRESSURE SENSOR procedure 4 is carried out, DTC 51 is memorized.
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
WIRING DIAGRAM:

VDC00150

10

9

11

12

15

13

16

14

VDC HYDRAULIC UNIT

VALVE RELAY

87

87a

VDC2

VDC1

4

6

86

1

85

30

30

86

85

87

5

VDC4

F90

VDC5

F91

F87

56 57

59 60

62 63

65

82 83

80

27

28

25

26

23

24

21

22

19

20

17

18

15

16

13

14

11

12

9

10

7

8

5

6

3

4

1

2

54

55

52

53

50

51

81

48

49

46

47

44

45

78

79

76

77

75

42

43

40

41

74

72

73

70

71

39

37

38

35

36

69

67

68

66

33

34

61

64

31

32

29

30

58

SBF-3 50A

VDC7

VDC6

MOTOR RELAY

VALVE RELAY

VDC CONTROL MODULE

22

10

27

47

F87

1
2

F89

VDC3

1

SBF-1 100A

RELAY BOX

F89

VDC1

1 2

F90

1

3

4 5 6

2

NO. 8 30A 

FR OUTLET

FR INLET

RL OUTLET

RL INLET

RR OUTLET

RR INLET

PRIMAR

Y CUT

PRIMAR

Y SECTION

SECOND

AR

Y CUT

PRIMAR

Y

PRESSURE SENSOR

SECOND

A

R

Y

PRESSURE SENSOR

SECOND

AR

Y SECTION

FL OUTLET

FL INLET

51

30

3

31

4

23

50

24

25

2

26

36

76

77

78

29

4

5

1

6

2

7

3

8

85

86

87

87a

30

85

86

87

30

F91

VDC6

VDC7

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

BATTERY

VDC-101

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

Step

Value

Yes

No

1

CHECK RESISTANCE OF VALVE RELAY.
1) Turn ignition switch to OFF.
2) Remove valve relay from relay box.
3) Measure resistance between valve relay 

terminals.

Terminals

No. 85 — No. 86:

Is the measured value within the specified 
range?

93 — 113 

Ω

Go to step 2.

Replace valve 
relay.

2

CHECK CONTACT POINT OF VALVE RE-
LAY.
1) Connect battery to valve relay terminals 

No. 85 and No. 86.

2) Measure resistance between valve relay 

terminals.

Terminals

No. 30 — No. 87:

Is the measured value less than the speci-
fied value?

0.5 

Ω

Go to step 3.

Replace valve 
relay.

3

CHECK CONTACT POINT OF VALVE RE-
LAY.
Measure resistance between valve relay termi-
nals.

Terminals

No. 30 — No. 87a:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 4.

Replace valve 
relay.

4

CHECK CONTACT POINT OF VALVE RE-
LAY.
1) Disconnect battery from valve relay termi-

nals.

2) Measure resistance between valve relay 

terminals.

Terminals

No. 30 — No. 87:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 5.

Replace valve 
relay.

5

CHECK CONTACT POINT OF VALVE RE-
LAY.
Measure resistance between valve relay termi-
nals.

Terminals

No. 30 — No. 87a:

Is the measured value less than the specified 
value?

0.5 

Ω

Go to step 6.

Replace valve 
relay.

6

CHECK SHORT OF VALVE RELAY.
Measure resistance between valve relay termi-
nals.

Terminals

No. 86 — No. 87:
No. 86 — No. 87a:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 7.

Replace valve 
relay.

VDC-102

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

7

CHECK POWER SUPPLY FOR VALVE RE-
LAY.
1) Disconnect connector (F89) from relay box.
2) Measure voltage between relay box con-

nector and chassis ground.

Connector & terminal

(F89) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 — 15 V

Go to step 8.

Repair harness 
between battery 
and relay box con-
nector. Check fuse 
No. 8.

8

CHECK OPEN CIRCUIT AND GROUND 
SHORT IN POWER SUPPLY CIRCUIT OF 
RELAY BOX.
1) Disconnect connector (VDC1) from VDCH/

U.

2) Connect connector (F89) to relay box.
3) Measure voltage of relay box.

Connector & terminal

(VDC6) No. 87 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 — 15 V

Go to step 9.

Replace relay box 
and check fuse 
No. 8.

9

CHECK OPEN CIRCUIT IN CONTROL CIR-
CUIT OF RELAY BOX.
1) Turn ignition switch to OFF.
2) Disconnect connector (F90) from relay box.
3) Measure resistance between  relay box 

connector and valve relay installing point.

Connector & terminal

(VDC4) No. 5 — (VDC6) No. 85:
(VDC4) No. 1 — (VDC6) No. 86:

Is the measured value less than the speci-
fied value?

0.5 

Ω

Go to step 10.

Replace relay box.

10

CHECK GROUND SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
Measure resistance between  relay box con-
nector and chassis ground.

Connector & terminal

(VDC4) No. 5 (+) — Chassis ground (

−−−−

):

(VDC4) No. 1 (+)— Chassis ground (

−−−−

):

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 11.

Replace relay box 
and check fuse 
No. 8.

11

CHECK BATTERY SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
Measure voltage between  relay box connector 
and chassis ground.

Connector & terminal

(VDC4) No. 5 (+) — Chassis ground (

−−−−

):

(VDC4) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

1 V

Go to step 12.

Replace relay box. 
Check fuse No. 8.

Step

Value

Yes

No

VDC-103

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

12

CHECK BATTERY SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
1) Turn ignition switch to ON.
2) Measure voltage between  relay box con-

nector and chassis ground.

Connector & terminal

(VDC4) No. 5 (+) — Chassis ground (

−−−−

):

(VDC4) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value less than the speci-
fied value?

1 V

Go to step 13.

Replace relay box. 
Check fuse No. 8.

13

CHECK OPEN CIRCUIT IN CONTROL SYS-
TEM HARNESS OF VALVE RELAY.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Measure resistance between VDCCM con-

nector and relay box connector.

Connector & terminal

(F87) No. 47 — (F90) No. 5:
(F87) No. 27 — (F90) No. 1:

Is the measured value less than the speci-
fied value?

0.5 

Ω

Go to step 14.

Repair harness 
between VDCCM 
and relay box.

14

CHECK GROUND SHORT IN CONTROL 
SYSTEM HARNESS OF VALVE RELAY.
Measure resistance between VDCCM connec-
tor and chassis ground.

Connector & terminal

(F87) No. 47 (+) — Chassis ground (

−−−−

):

(F87) No. 27 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 15.

Repair harness 
between VDCCM 
and relay box and 
check all fuses.

15

CHECK BATTERY SHORT IN CONTROL 
SYSTEM HARNESS OF VALVE RELAY.
Measure voltage between VDCCM connector 
and chassis ground.

Connector & terminal

(F87) No. 27 (+) — Chassis ground (

−−−−

):

(F87) No. 47 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

1 V

Go to step 16.

Repair harness 
between VDCCM 
and relay box.

16

CHECK BATTERY SHORT IN CONTROL 
SYSTEM HARNESS OF VALVE RELAY.
1) Turn ignition switch to ON.
2) Measure voltage between VDCCM connec-

tor and chassis ground.

Connector & terminal

(F87) No. 27 (+) — Chassis ground (

−−−−

):

(F87) No. 47 (+) — Chassis ground (

−−−−

):

Is the measured value less than the speci-
fied value?

1 V

Go to step 17.

Repair harness 
between VDCCM 
and relay box.

17

CHECK OPEN CIRCUIT IN CONTACT POINT 
CIRCUIT OF RELAY BOX.
Measure resistance between VDCH/U connec-
tor and valve relay installing point.

Connector & terminal

(VDC1) No. 2 — (VDC6) No. 30:

Is the measured value less than the specified 
value?

0.5 

Ω

Go to step 18.

Replace relay box.

Step

Value

Yes

No