Subaru Legacy III (2000-2003 year). Manual — part 330

EN(H6DO)-122

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector

and chassis ground.

Connector & terminal

(B137) No. 6 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

8 V

Go to step 3.

Go to step 2.

2

CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector and
chassis ground.

Connector & terminal

(B137) No. 7 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

8 V

Go to step 3.

Go to step 4.

3

CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1) Turn ignition switch to OFF.
2) Repair battery short circuit in harness

between ECM and front oxygen (A/F) sen-
sor connector.

3) Turn ignition switch to ON.
4) Read data of front oxygen (A/F) sensor

heater current using Subaru Select Monitor
or the OBD-II general scan tool.
Does the measured value exceed the spec-
ified value?

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”.
<Ref. to EN(H6DO)-34, Subaru Select Moni-
tor.>
• OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.

2.3 A

Replace ECM.
<Ref. to
FU(H6DO)-46,
Engine Control
Module.>

END

4

CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector and
chassis ground.

Connector & terminal

(B137) No. 6 (+) — Chassis ground (

−−−−

):

Does the voltage change more than the speci-
fied value shaking harness and connector of
ECM while monitoring the value with voltage
meter?

8 V

Repair battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.

Go to step 5.

5

CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector and
chassis ground.

Connector & terminal

(B137) No. 7 (+) — Chassis ground (

−−−−

):

Does the voltage change more than the speci-
fied value by shaking harness and connector
of ECM while monitoring the value with voltage
meter?

8 V

Repair battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.

END

EN(H6DO)-123

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO:

EN(H6DO)-124

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

I:

DTC P0068 — MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRES-
SURE CIRCUIT RANGE/PERFORMANCE —

• DTC DETECTING CONDITION:

• Two consecutive driving cycles with fault

• TROUBLE SYMPTOM

• Erroneous idling

CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H6DO)-54, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H6DO)-47, OPERATION, Inspec-
tion Mode.>.

• WIRING DIAGRAM:

EN-00811

9

19

8

5

8

B135

B20

E1

16

13

14

B83

E21

1 2 3

B83

B20

B135

ECM

3

2

1

E21

INTAKE MANIFOLD
PRESSURE SENSOR

THROTTLE BODY

5 6

7 8

2

1

9

4

3

10

24

22

23

25

11 12 13 14 15

26 27 28

16 17 18 19

20 21

1 2 3 4
5 6 7 8
9 10 11 12

13 14 15 16

1 2 3 4

5 6 7 8 9 10

11 12

19 20

13 14 15 16 17 18

EN(H6DO)-125

ENGINE (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK IDLE SWITCH SIGNAL.
1) Turn ignition switch to ON.
2) Operate the LED operation mode for

engine using Subaru Select Monitor.
Does the LED of {Idle Switch Signal} come
on?

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to the
“LED OPERATION MODE FOR ENGINE”.
<Ref. to EN(H6DO)-34, Subaru Select Moni-
tor.>

LED comes on.

Go to step 2.

Check throttle
position sensor cir-
cuit. <Ref. to
EN(H6DO)-148,
DTC P0121 —
THROTTLE/
PEDAL POSI-
TION SENSOR/
SWITCH “A” CIR-
CUIT RANGE/
PERFORMANCE
—, Diagnostic Pro-
cedure with Diag-
nostic Trouble
Code (DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0106.

2

CHECK ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?

Another DTC is displayed.

Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H6DO)-89, List
of Diagnostic
Trouble Code
(DTC).>

NOTE:
In this case, it is
not necessary to
inspect DTC
P0106.

Go to step 3.

3

CHECK CONDITION OF INTAKE MANIFOLD
PRESSURE SENSOR.
Is the intake manifold pressure sensor installa-
tion bolt tightened securely?

Tightened securely.

Go to step 4.

Tighten intake
manifold pressure
sensor installation
bolt securely.

4

CHECK CONDITION OF THROTTLE BODY.
Is the throttle body installation bolt tightened
securely?

Tightened securely.

Go to step 5.

Tighten throttle
body installation
bolt securely.

5

CHECK CONDITION OF EGR VALVE.
Is there any foreign object caught between
EGR solenoid valve and intake manifold?

There is a foreign object.

Completely
remove foreign
object, and install
EGR solenoid
valve securely to
the intake mani-
fold.

Replace intake
manifold pressure
sensor. <Ref. to
FU(H6DO)-34,
Intake Manifold
Pressure Sensor.>