Subaru Legacy III (2000-2003 year). Manual - part 793

VDC-208

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

AL:DTC 51 VALVE RELAY ON FAILURE

DIAGNOSIS:
• Faulty valve relay

NOTE:
When DTC 74 inspection 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-209

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

Step

Value

Yes

No

1

CHECK CONTACT POINT OF VALVE RE-
LAY.
1) Turn ignition switch to OFF.
2) Remove valve relay from relay box.
3) Connect battery to valve relay terminals 

No. 85 and No. 86.

4) 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 2.

Replace valve 
relay.

2

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 3.

Replace valve 
relay.

3

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 4.

Replace valve 
relay.

4

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 5.

Replace valve 
relay.

5

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 6.

Replace valve 
relay.

6

CHECK BATTERY SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
1) Disconnect connector (F90) from relay box.
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 7.

Replace relay box. 
Check fuse No. 8 
and SBF3.

VDC-210

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

7

CHECK BATTERY SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
1) Turn ignition switch to ON.
2) Measure voltage between VDCH/U 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 8.

Replace relay box. 
Check fuse No. 8 
and SBF3.

8

CHECK BATTERY SHORT IN CONTROL 
SYSTEM HARNESS OF VALVE RELAY.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Disconnect connector from VDCH/U.
4) 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 9.

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

9

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 10.

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

10

CHECK BATTERY SHORT IN CONTACT 
POINT CIRCUIT OF RELAY BOX.
1) Disconnect connector VDC1 from relay 

box.

2) Measure voltage between VDCH/U con-

nector and chassis ground.

Connector & terminal

(VDC1) No. 2 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 11.

Replace relay box.

11

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

nector and chassis ground.

Connector & terminal

(VDC1) No. 2 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 12.

Replace relay box.

Step

Value

Yes

No

VDC-211

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

12

CHECK BATTERY SHORT OF SOLENOID 
VALVE.
1) Turn ignition switch to OFF.
2) Measure voltage between VDCH/U con-

nector and chassis ground.

Connector & terminal

(VDC2) No. 2 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 13.

Replace VDCH/U 
and check all 
fuses.  <Ref. to 
VDC-8, VDC Con-
trol Module 
(VDCCM).>

13

CHECK BATTERY SHORT OF SOLENOID 
VALVE.
1) Turn ignition switch to ON.
2) Measure voltage between VDCH/U con-

nector and chassis ground.

Connector & terminal

(VDC2) No. 2 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 14.

Replace VDCH/U 
and check all 
fuses.  <Ref. to 
VDC-8, VDC Con-
trol Module 
(VDCCM).>

14

CHECK BATTERY SHORT OF HARNESS.
1) Turn ignition switch to OFF.
2) Measure voltage between VDCCM connec-

tor and chassis ground.

Connector & terminal

(F87) No. 30 (+) — Chassis ground (

−−−−

):

(F87) No. 24 (+) — Chassis ground (

−−−−

):

(F87) No. 23 (+) — Chassis ground (

−−−−

):

(F87) No. 31 (+) — Chassis ground (

−−−−

):

(F87) No. 26 (+) — Chassis ground (

−−−−

):

(F87) No. 25 (+) — Chassis ground (

−−−−

):

(F87) No. 3 (+) — Chassis ground (

−−−−

):

(F87) No. 51 (+) — Chassis ground (

−−−−

):

(F87) No. 50 (+) — Chassis ground (

−−−−

):

(F87) No. 4 (+) — Chassis ground (

−−−−

):

(F87) No. 2 (+) — Chassis ground (

−−−−

):

(F87) No. 29 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 15.

Repair harness 
between VDCH/U 
and VDCCM and 
check all fuses.

15

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

tor and chassis ground.

Connector & terminal

(F87) No. 30 (+) — Chassis ground (

−−−−

):

(F87) No. 24 (+) — Chassis ground (

−−−−

):

(F87) No. 23 (+) — Chassis ground (

−−−−

):

(F87) No. 31 (+) — Chassis ground (

−−−−

):

(F87) No. 26 (+) — Chassis ground (

−−−−

):

(F87) No. 25 (+) — Chassis ground (

−−−−

):

(F87) No. 3 (+) — Chassis ground (

−−−−

):

(F87) No. 51 (+) — Chassis ground (

−−−−

):

(F87) No. 50 (+) — Chassis ground (

−−−−

):

(F87) No. 4 (+) — Chassis ground (

−−−−

):

(F87) No. 2 (+) — Chassis ground (

−−−−

):

(F87) No. 29 (+) — Chassis ground (

−−−−

):

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

1 V

Go to step 16.

Repair harness 
between VDCH/U 
and VDCCM and 
check all fuses.

Step

Value

Yes

No