Subaru Legacy III (2000-2003 year). Service manual — part 729

ABS-134

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

AE:DTC 56 OPEN OR SHORT CIRCUIT IN G SENSOR CIRCUIT

DIAGNOSIS:
• Faulty G sensor output voltage
TROUBLE SYMPTOM:
• ABS does not operate.
WIRING DIAGRAM:

ABS00312

F55

R70

F62

ABS CONTROL MODULE AND
HYDRAULIC CONTROL UNIT

ABS

G SENSOR

F49

2

1

3

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

3

7

6

28

1

2

3

F55

R49

R70

2

8

30

1

2 3

4 5 6 7 8

ABS-135

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

Step

Value

Yes

No

1

CHECK OUTPUT OF G SENSOR USING SE-
LECT MONITOR.
1) Select “Current data display & Save” on the

select monitor.

2) Read the G sensor output in select monitor

data display.
Is the G sensor output on the monitor dis-
play within the specified range when the G
sensor is in horizontal position?

2.1 - 2.5 V

Go to step 2.

Go to step 5.

2

CHECK POOR CONTACT IN CONNECTORS.
Is there poor contact in connector between
ABSCM&H/U and G sensor?

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.

5

CHECK INPUT VOLTAGE OF G SENSOR.
1) Turn ignition switch to OFF.
2) Remove console box.
3) Disconnect G sensor from body. (Do not

disconnect connector.)

4) Turn ignition switch to ON.
5) Measure voltage between G sensor con-

nector terminals.

Connector & terminal

(R70) No. 1 (+) — No. 3 (

−−−−

):

Is the measured value within the specified
range?

4.75 - 5.25 V

Go to step 6.

Repair harness/
connector
between G sensor
and ABSCM&H/U.

6

CHECK OPEN CIRCUIT IN G SENSOR OUT-
PUT HARNESS AND GROUND HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABSCM&H/U.
3) Measure resistance between ABSCM&H/U

connector terminals.

Connector & terminal

(F49) No. 6 — No. 28:

Is the measured value within the specified
range?

5.0 - 5.6 k

Ω

Go to step 7.

Repair harness/
connector
between G sensor
and ABSCM&H/U.

7

CHECK GROUND SHORT IN G SENSOR
OUTPUT HARNESS.
1) Disconnect connector from G sensor.
2) Measure resistance between ABSCM&H/U

connector and chassis ground.

Connector & terminal

(F49) No. 6 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 8.

Repair harness
between G sensor
and ABSCM&H/U.

ABS-136

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

8

CHECK G SENSOR.
1) Connect connector to G sensor.
2) Connect connector to ABSCM&H/U.
3) Turn ignition switch to ON.
4) Measure voltage between G sensor con-

nector terminals.

Connector & terminal

(R70) No. 2 (+) — No. 3 (

−−−−

):

Is the voltage between within the specified
range when G sensor is horizontal?

2.1 - 2.5 V

Go to step 9.

Replace G sen-
sor. <Ref. to ABS-
21, G Sensor.>

9

CHECK G SENSOR.
Measure voltage between G sensor connector
terminals.

Connector & terminal

(R70) No. 2 (+) — No. 3 (

−−−−

):

Is the voltage between within the specified
range when G sensor is inclined forwards to
90

°

?

3.7 - 4.1 V

Go to step 10.

Replace G sen-
sor. <Ref. to ABS-
21, G Sensor.>

10

CHECK G SENSOR.
Measure voltage between G sensor connector
terminals.

Connector & terminal

(R70) No. 2 (+) — No. 3 (

−−−−

):

Is the voltage between within the specified
range when G sensor is inclined backwards to
90

°

?

0.5 - 0.9 V

Go to step 11.

Replace G sen-
sor. <Ref. to ABS-
21, G SENSOR, .>

11

CHECK POOR CONTACT IN CONNECTORS.
Turn ignition switch to OFF.
Is there poor contact in connector between
ABSCM&H/U and G sensor?

There is no poor contact.

Go to step 12.

Repair connector.

12

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 13.

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

13

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.

Step

Value

Yes

No

ABS-137

ABS (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR

MEMO: