Subaru LEGACY 2006 Manual page 161

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(diag)-26, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
2 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the engine
coolant temperature sensor.
3) Measure the voltage between engine cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
3 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between engine cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
4 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
Measure the voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (–):
Check
Is the engine coolant tempera-
ture less than –40°C (–40°F) ?
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 4 V?
EN(H4SO)(diag)-124
Yes No
Go to step 2. Repair the poor
contact.
NOTE:
In this case, repair
the following item:
• Poor contact of
engine coolant tem-
perature sensor
• Poor contact in
ECM
• Poor contact of
coupling connector
• Poor contact of
joint connector
Go to step 3.
short circuit of har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 4.
short circuit of har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 5. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector
• Poor contact of
engine coolant tem-
perature sensor
connector
• Poor contact in
ECM connector
• Poor contact of
coupling connector
• Poor contact of
joint connector