Subaru Legacy III (2000-2003 year). Manual - part 773

VDC-128

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

7

CHECK GROUND SHORT OF HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Measure resistance between VDCH/U con-

nector and chassis ground.

Connector & terminal

(F91) No. 13 — Chassis ground:
(F91) No. 14 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 8.

Repair harness 
between VDCH/U 
and VDCCM.

8

CHECK BATTERY SHORT OF HARNESS.
Measure voltage between VDCH/U connector 
and chassis ground.

Connector & terminal

(F91) No. 13 (+) — Chassis ground (

−−−−

):

(F91) No. 14 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified 
value?

0.5 V

Go to step 9.

Repair harness 
between VDCH/U 
and VDCCM.

9

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

nector and chassis ground.

Connector & terminal

(F91) No. 13 (+) — Chassis ground (

−−−−

):

(F91) No. 14 (+) — Chassis ground (

−−−−

):

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

0.5 V

Go to step 10.

Repair harness 
between VDCH/U 
and VDCCM.

10

CHECK OUTPUT VOLTAGE OF PRESSURE 
SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Remove cover from VDCCM. <Ref. to 

VDC-19, REMOVE, VDCCM Connector 
Cover.>

4) Connect connector to VDCCM.
5) Connect all connectors.
6) Turn ignition switch to ON.
7) Do not depress brake pedal.
8) Measure voltage between VDCCM connec-

tor terminals.

Connector & terminal

(F87) No. 77 (+) — No. 76 (

−−−−

):

(F87) No. 36 (+) — No. 76 (

−−−−

):

Is the measured value within the specified 
range?

0.48 — 0.72 V

Go to step 11.

Replace VDCH/U.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>

11

CHECK BRAKE FLUID LEAKAGE.
Inspect fluid leakage between brake master 
cylinder and VDCH/U.
Does brake fluid leak?

Fluid leaks.

Retighten or 
replace.

Go to step 12.

12

CHECK BRAKE MASTER CYLINDER.
Inspect brake master cylinder hydraulic pres-
sure.  <Ref. to BR-36, OPERATION CHECK 
(WITH GAUGES), INSPECTION, Brake 
Booster.>
Is hydraulic pressure normal?

Normal.

Go to step 13.

Replace master 
cylinder.

Step

Value

Yes

No

VDC-129

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR

13

CHECK BRAKE PEDAL STROKE.
Measure the stroke between non-forced pedal 
position and forced pedal position with 50 kg 
(110 lb).
Is the measured value less than the specified 
value?

95 mm (3.74 in)

Go to step 14.

Perform bleeding.

14

CHECK INPUT VOLTAGE OF PRESSURE 
SENSOR.
1) Depress the brake pedal with 50 kg (110 

lb).

2) Measure voltage between VDCCM connec-

tor terminals.

Connector & terminal

A (F87) No. 77 (+) — No. 76 (

−−−−

):

B (F87) No. 36 (+) — No. 76 (

−−−−

):

Does the voltage difference between A and 
B exceed the specified value?

0.2 V

Go to step 15.

Replace VDCH/U.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>

15

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connector between 
VDCCM and pressure sensor?

There is poor contact.

Repair connector.

Go to step 16.

16

CHECK VDCCM.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the diagnostic trouble code.

Is the same diagnostic trouble code as in 
the current diagnosis still being output?

Same pattern.

Replace VDCCM.  
<Ref. to VDC-8, 
VDC Control Mod-
ule (VDCCM).>

Go to step 17.

17

CHECK ANY OTHER DIAGNOSTIC TROU-
BLE CODES APPEARANCE.
Are other diagnostic trouble codes being out-
put?

Other DTC indicated.

Proceed with the 
diagnosis corre-
sponding to the 
diagnostic trouble 
code.

A temporary poor 
contact.

Step

Value

Yes

No

VDC-130

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

14.Diagnostics Chart with Select Monitor

A: COMMUNICATION FOR INITIALIZING IMPOSSIBLE (SELECT MONITOR 

COMMUNICATION FAILURE)

DIAGNOSIS:
• Faulty harness connector
TROUBLE SYMPTOM:
• ABS warning light remains on.
WIRING DIAGRAM:

VDC00183

5

4

11

38

2

1

B40

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

VDC CONTROL MODULE

1

55

28

F87

SBF-1 100A

GENERATOR

IGNITION 
SWITCH

SBF-4 50A

DATA LINK

CONNECTOR

B40

NO

. 18 15A

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16

BATTERY

R

L

: RHD MODEL

: LHD MODEL

B62

L

:

F45

L

:

F2

R

:

F45

L

:

B100

R

:

F2

R

:

1 2 3 4

5 6 7

8 9 10 11 12 13 14 15 16

3 4

1 2

8 9 10 11

12 13 14 15 16 17 18 19 20 21 22 23 24

5 6

7

VDC-131

VDC (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SELECT MONITOR

Step

Value

Yes

No

1

CHECK IGNITION SWITCH. 

Is ignition switch to ON? 

Go to step 2.

Turn ignition 
switch to ON, and 
select VDCCM 
mode using the 
select monitor.

2

CHECK BATTERY.
1) Turn ignition switch to OFF.
2) Measure battery voltage.

Does the measured value exceed the spec-
ified value?

11 V

Go to step 3.

Charge or replace 
battery.

3

CHECK BATTERY TERMINAL.
Is there poor contact at battery terminal?

There is poor contact.

Repair or tighten 
battery terminal.

Go to step 4.

4

CHECK COMMUNICATION OF SELECT 
MONITOR.
1) Turn ignition switch to ON.
2) Using the select monitor, check whether 

communication to other systems can be 
executed normally.
Are the name and year of the system dis-
played on the select monitor?

Displayed.

Go to step 9.

Go to step 5.

5

CHECK COMMUNICATION OF SELECT 
MONITOR.
1) Turn ignition switch to OFF.
2) Disconnect VDCCM connector.
3) Check whether communication to other 

systems can be executed normally.
Are the name and year of the system dis-
played on the select monitor?

Displayed.

Go to step 10.

Go to step 6.

6

CHECK COMMUNICATION OF SELECT 
MONITOR.
1) Turn ignition switch to OFF.
2) Connect VDCCM module connector.
3) Disconnect cruise control module connec-

tor.

4) Check whether communication to other 

systems can be executed normally.
Are the name and year of the system dis-
played on the select monitor?

NOTE:

If the vehicle is not equipped with cruise control:
Go to step 7.

Displayed.

Inspect cruise con-
trol module.

Go to step 7.

7

CHECK HARNESS CONNECTOR BETWEEN 
EACH CONTROL MODULE AND DATA LINK 
CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect VDCCM, and cruise control 

module connectors.

3) Measure resistance between data link con-

nector and chassis ground.

Connector & terminal

(B40) No. 5 — Chassis ground:
(B40) No. 4 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 8.

Repair harness 
and connector 
between each 
control module 
and data link con-
nector.