Subaru Legacy 2003 Service Manual page 522

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK CURRENT DATA.
1) Start engine.
2) Read data of engine coolant temperature
sensor signal using Subaru Select Monitor
or OBD-II general scan tool.
Is the measured value less than the speci-
fied value?
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)-32, Subaru Select Moni-
tor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from engine coolant
temperature sensor.
3) Measure voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
3 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn ignition switch to ON.
2) Measure voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
Value
−40°C (−40°F)
10 V
10 V
EN(H4SO)-125
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair poor con-
tact.
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 battery Go to step 3.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Repair battery Go to step 4.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
No