Subaru Legacy III (2000-2003 year). Manual - part 724

ABS-114

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

U: DTC 42 POWER SUPPLY VOLTAGE TOO LOW

DIAGNOSIS:
• Power source voltage of the ABSCM&H/U is low.
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00294

1

23

ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT

F49

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16 17 18 19 20 21 22

27 28 29 30 31

23

24

25

26

F49

BATTERY

NO

. 18 15A

SBF-4 50A

SBF-1 100A

GENERATOR

IGNITION 
SWITCH

ABS-115

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK GENERATOR.
1) Start engine.
2) Idling after warm-up.
3) Measure voltage between generator B ter-

minal and chassis ground.

Terminal

Generator B terminal — Chassis 
ground:

Is the measured value within the specified 
range?

10 - 15 V

Go to step 2.

i) Repair genera-
tor.
ii) H4 engine 
model:
iii) <Ref. to 
SC(H4SO)-14, 
Generator.>
iv) H6 engine 
model:
v) <Ref. to 
SC(H6DO)-14, 
Generator.>

2

CHECK BATTERY TERMINAL.
Turn ignition switch to OFF.
Are the positive and negative battery terminals 
tightly clamped?

Terminals are tightened 
securely.

Go to step 3.

Tighten the clamp 
of terminal.

3

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Disconnect connector from ABSCM&H/U.
2) Run the engine at idle.
3) Measure voltage between ABSCM&H/U 

connector and chassis ground.

Connector & terminal

(F49) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 - 15 V

Go to step 4.

Repair harness 
connector 
between battery, 
ignition switch and 
ABSCM&H/U.

4

CHECK GROUND CIRCUIT OF ABSCM&H/U.
1) Turn ignition switch to OFF.
2) Measure resistance between ABSCM&H/U 

connector and chassis ground.

Connector & terminal

(F49) No. 23 — Chassis ground:

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

0.5 

Ω

Go to step 5.

Repair 
ABSCM&H/U 
ground harness.

5

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connectors between 
generator, battery and ABSCM&H/U?

There is no poor contact.

Go to step 6.

Repair connector.

6

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the DTC.

Is the same DTC still being output?

Same DTC is not indicated.

Go to step 7.

Replace 
ABSCM&H/U.  
<Ref. to ABS-6, 
ABS Control Mod-
ule and Hydraulic 
Control Unit 
(ABSCM&H/U).> 

7

CHECK ANY OTHER DTC APPEARANCE.
Are other DTC being output?

Other DTC is not indicated.

A temporary poor 
contact.

Proceed with the 
diagnosis corre-
sponding to the 
DTC.

ABS-116

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

V: DTC 42 POWER SUPPLY VOLTAGE TOO HIGH

DIAGNOSIS:
• Power source voltage of the ABSCM&H/U is high.
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00294

1

23

ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT

F49

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16 17 18 19 20 21 22

27 28 29 30 31

23

24

25

26

F49

BATTERY

NO

. 18 15A

SBF-4 50A

SBF-1 100A

GENERATOR

IGNITION 
SWITCH

ABS-117

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK GENERATOR.
1) Start engine.
2) Idling after warm-up.
3) Measure voltage between generator B ter-

minal and chassis ground.

Terminal

Generator B terminal — Chassis 
ground:

Is the measured value within the specified 
range?

10 - 17 V

Go to step 2.

i) Repair genera-
tor.
ii) H4 engine 
model:
iii) <Ref. to 
SC(H4SO)-14, 
Generator.>
iv) H6 engine 
model:
v) <Ref. to 
SC(H6DO)-14, 
Generator.>

2

CHECK BATTERY TERMINAL.
Turn ignition switch to OFF.
Are the positive and negative battery terminals 
tightly clamped?

Terminals are tightened 
securely.

Go to step 3.

Tighten the clamp 
of terminal.

3

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Disconnect connector from ABSCM&H/U.
2) Run the engine at idle.
3) Measure voltage between ABSCM&H/U 

connector and chassis ground.

Connector & terminal

(F49) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 - 17 V

Go to step 4.

Repair harness 
connector 
between battery, 
ignition switch and 
ABSCM&H/U.

4

CHECK GROUND CIRCUIT OF ABSCM&H/U.
1) Turn ignition switch to OFF.
2) Measure resistance between ABSCM&H/U 

connector and chassis ground.

Connector & terminal

(F49) No. 23 — Chassis ground:

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

0.5 

Ω

Go to step 5.

Repair 
ABSCM&H/U 
ground harness.

5

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connectors between 
generator, battery and ABSCM&H/U?

There is no poor contact.

Go to step 6.

Repair connector.

6

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the DTC.

Is the same DTC still being output?

Same DTC is not indicated.

Go to step 7.

Replace 
ABSCM&H/U.  
<Ref. to ABS-6, 
ABS Control Mod-
ule and Hydraulic 
Control Unit 
(ABSCM&H/U).> 

7

CHECK ANY OTHER DTC APPEARANCE.
Are other DTC being output?

Other DTC is not indicated.

A temporary poor 
contact.

Proceed with the 
diagnosis corre-
sponding to the 
DTC.