Subaru Legacy 2003 Service Manual page 1924

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake manifold absolute
pressure signal using Subaru Select Moni-
tor.
Is the measured value less than the speci-
fied value?
NOTE:
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>
2 CHECK POOR CONTACT.
Check the poor contact in ECM and pressure
sensor connector.
Is there poor contact in ECM or pressure sen-
sor connector?
3 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 9 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the specified
value?
4 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 9 (+) — Chassis ground ( − − − − ):
Does the measured value change by shaking
harness and connector of ECM while monitor-
ing the value with voltage meter?
5 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B135) No. 8 (+) — Chassis ground ( − − − − ):
Is the measured value less than the specified
value?
6 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from pressure
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between pressure
sensor connector and engine ground.
Connector & terminal
(E21) No. 3 (+) — Engine ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
Value
−7.2 kPa (−54 mmHg, −2.1
inHg)
There is poor contact.
4.5 V
The value changes.
0.7 V
4.5 V
EN(H4DOSTC)-85
ENGINE (DIAGNOSTICS)
Yes
Go to step 3. Go to step 2.
Repair the poor Even if MI lights
contact in ECM or up, the circuit has
pressure sensor returned to a nor-
connector. mal condition at
this time.
Go to step 5. Go to step 4.
Repair the poor Contact SUBARU
contact in ECM distributor service.
connector.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Go to step 6. Contact SUBARU
distributor service.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Go to step 7. Repair the open
circuit in harness
between ECM and
intake manifold
pressure sensor
connector.
No
be-
probable
multiple
be-
probable
multiple