Subaru 2009 IMPREZA Service Manual page 592

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of the oil temperature sensor
signal using the Subaru Select Monitor or gen-
eral 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 POOR CONTACT.
Check for poor contact of ECM and oil tempera-
ture sensor connector.
3 CHECK HARNESS BETWEEN ECM AND OIL
TEMPERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and oil
temperature sensor.
3) Measure the resistance of the harness
between ECM and oil temperature sensor con-
nector.
Connector & terminal
(B134) No. 23 — (E75) No. 2:
(B134) No. 29 — (E75) No. 1:
4 CHECK HARNESS BETWEEN ECM AND OIL
TEMPERATURE SENSOR CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground (–):
Check
Is the oil temperature less than
–40°C (–40°F)?
Is there poor contact of ECM or
oil temperature sensor connec-
tor?
Is the resistance less than 1 ? Go to step 4.
Is the voltage 5 V or more?
EN(H4SO)(diag)-175
ENGINE (DIAGNOSTICS)
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.
Repair the poor Go to step 3.
contact of ECM or
the oil temperature
sensor connector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and oil tem-
perature
connector
• Poor contact of
coupling connector
Repair the short Replace the oil
circuit to power temperature sen-
supply in harness sor. <Ref. to
between ECM and FU(H4SO)-40, Oil
oil temperature Temperature Sen-
sensor connector. sor.>
sensor