Subaru Legacy 2003 Service Manual page 1940

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select
Monitor.
Is the measured value less than the speci-
fied value?
NOTE:
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOSTC)-26, Subaru Select Monitor.>
2 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from engine cool-
ant temperature sensor.
3) Measure the voltage between engine cool-
ant temperature sensor connector and
engine ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
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 ( − − − − ):
Does the measured value exceed the spec-
ified value?
Value
−40°C (−40°F)
10 V
10 V
EN(H4DOSTC)-101
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the poor
contact.
NOTE:
In this case, repair
the following:
• Poor contact in
engine coolant
temperature sen-
sor
• Poor contact in
ECM
• Poor contact in
coupling connector
• Poor contact in
joint connector
Repair the battery Go to step 3.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Repair the battery Go to step 4.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
No