Subaru Legacy 2004 Service Manual page 519

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 Monitor.
NOTE:
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.0)(diag)-25, Subaru Select Mon-
itor.>
2 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 17 (+) — Chassis ground (
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 17 (+) — Chassis ground (
4 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 20 (+) — Chassis ground (
5 CHECK INPUT SIGNAL FOR ECM (USING
SUBARU SELECT MONITOR).
Read the data of atmospheric absolute pres-
sure signal using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.0)(diag)-25, Subaru Select Mon-
itor.>
6 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from manifold
absolute pressure sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between manifold
absolute pressure sensor connector and
engine ground.
Connector & terminal
(E21) No. 3 (+) — Engine ground (
7 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and manifold absolute pressure
sensor connector.
Connector & terminal
(B136) No. 20 — (E21) No. 2:
Check
Is the value more than 119.5
kPa (896.5 mmHg, 35.29
inHg)?
Is the voltage more than 4.5 V? Go to step 4.
"
):
Does the voltage change by
shaking the ECM harness and
connector?
"
):
Is the voltage less than 0.2 V? Go to step 6.
"
):
Is the value more than 13.3
kPa (100 mmHg, 3.94 inHg)
when shaking the ECM har-
ness and connector?
Is the voltage more than 4.5 V? Go to step 7.
"
):
Is the resistance less than 1
&?
EN(H4SO 2.0)(diag)-87
ENGINE (DIAGNOSTICS)
Yes
Go to step 10. Go to step 2.
Go to step 3.
Repair the poor Replace the ECM.
contact in ECM <Ref. to FU(H4SO
connector. 2.0)-34, Engine
Control Module
(ECM).>
Go to step 5.
Repair the poor Go to step 6.
contact in ECM
connector.
Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
Go to step 8. Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
No