Subaru Legacy 2002 Service Manual page 1344

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(H6)-38, 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) Measure voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground (−):
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 (−):
4 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
Measure voltage between engine coolant tem-
perature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground (−):
Step
Is the value less than
−40°C (−40°F)?
Is the voltage more than 10
V?
Is the voltage more than 10
V?
Is the voltage less than 4.7
V?
EN(H6)-137
Check Yes
Go to step 2.
Repair battery
short circuit in
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Repair battery
short circuit in
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 5.
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
¼ Poor contact in
joint connector
Go to step 3.
Go to step 4.
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector
¼ Poor contact in
engine coolant
temperature sen-
sor connector
¼ Poor contact in
ECM connector
¼ Poor contact in
coupling connec-
tor
¼ Poor contact in
joint connector