Subaru Legacy 2002 Service Manual page 640

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
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.
NOTE:
¼ Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
¼ 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) Turn ignition switch to ON.
4) Read data of engine coolant temperature
sensor signal using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
¼ Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
¼ OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
Step
Is the value greater than
150°C (302°F)?
Is the value less than
−40°C (−40°F)?
EN-123
Check Yes
Go to step 2.
Replace engine
coolant tempera-
ture sensor. <Ref.
to FU-29, Engine
Coolant Tempera-
ture Sensor.>
Engine (Diagnostics)
No
Repair poor con-
tact.
NOTE:
In this case,
repair the follow-
ing:
¼ Poor contact in
engine coolant
temperature sen-
sor
¼ Poor contact in
ECM
¼ Poor contact in
coupling connec-
tor (B21)
¼ Poor contact in
joint connector
(B83)
Repair ground
short circuit in
harness between
engine coolant
temperature sen-
sor and ECM con-
nector.