Subaru 2009 IMPREZA Service Manual page 541

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake manifold absolute
pressure signal using Subaru Select Monitor or
general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
2 CHECK POWER SUPPLY OF MANIFOLD
ABSOLUTE PRESSURE SENSOR.
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 (–):
3 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance of harness between
ECM and manifold absolute pressure sensor
connector.
Connector & terminal
(B134) No. 6 — (E21) No. 1:
4 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 6 — Chassis ground:
5 CHECK POOR CONTACT.
Check for poor contact of ECM and manifold
absolute pressure sensor connector.
Check
Is the measured value less than
13.3 kPa (100 mmHg,
3.94 inHg)?
Is the voltage 4.5 V or more?
Is the resistance less than 1 ? Go to step 4.
Is the resistance 1 M or
more?
Is there poor contact of ECM or
manifold absolute pressure
sensor connector?
EN(H4SO)(diag)-124
Yes No
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.
Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and manifold
absolute pressure
sensor connector
• Poor contact of
ECM connector
• Poor contact of
coupling connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and manifold
absolute pressure
sensor connector
• Poor contact of
coupling connector
Go to step 5. Repair ground
short circuit of har-
ness between
ECM and manifold
absolute pressure
sensor connector.
Replace the mani-
Repair the poor
contact of ECM or fold absolute pres-
manifold absolute sure sensor. <Ref.
pressure sensor to FU(H4SO)-33,
connector. Manifold Absolute
Pressure Sensor.>