Subaru Legacy III (2000-2003 year). Manual - part 726

ABS-122

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Y: DTC 51 VALVE RELAY MALFUNCTION

DIAGNOSIS:
• Faulty valve relay
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00297

ABS CONTROL MODULE AND
HYDRAULIC CONTROL UNIT

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

24

1

23

VALVE RELAY

F49

MOTOR RELAY

FR OUTLET

FR INLET

RL OUTLET

RL INLET

RR OUTLET

RR INLET

FL OUTLET

FL INLET

SOLENOID

VA

L

V

E

PUMP MO

T

O

R

NO

. 8 30A

NO

. 18 15A

BATTERY

SBF-1 100A

SBF-3 50A

SBF-4 50A

IGNITION 
SWITCH

ABS-123

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

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

connector and chassis ground.

Connector & terminal

(F49) No. 1 (+) — Chassis ground (

−−−−

):

(F49) No. 24 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

10 - 15 V

Go to step 2.

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

2

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 3.

Repair 
ABSCM&H/U 
ground harness.

3

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 4.

Repair connector.

4

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 5.

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

5

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-124

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Z: DTC 51 VALVE RELAY ON FAILURE

DIAGNOSIS:
• Faulty valve relay
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00297

ABS CONTROL MODULE AND
HYDRAULIC CONTROL UNIT

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

24

1

23

VALVE RELAY

F49

MOTOR RELAY

FR OUTLET

FR INLET

RL OUTLET

RL INLET

RR OUTLET

RR INLET

FL OUTLET

FL INLET

SOLENOID

VA

L

V

E

PUMP MO

T

O

R

NO

. 8 30A

NO

. 18 15A

BATTERY

SBF-1 100A

SBF-3 50A

SBF-4 50A

IGNITION 
SWITCH

ABS-125

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK VALVE RELAY IN ABSCM&H/U.
Measure resistance between ABSCM&H/U ter-
minals.

Terminals

No. 23 — No. 24:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 2.

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

2

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 3.

Repair connector.

3

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 4.

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

4

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.