Subaru 2004 LEGACY Service Manual page 48

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 or
OBD-II general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to the
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to
EN(H6DO)(diag)-25, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
2 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
4 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 22 (+) — 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 procedures, refer to the
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to EN(H6DO)(di-
ag)-25, Subaru Select Monitor.>
6 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the 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
(E28) 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. 22 — (E28) 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
Ω?
EN(H6DO)(diag)-117
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
connector. FU(H6DO)-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