Subaru 2002 IMPREZA Service Manual page 561

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of engine coolant temperature
sensor signal using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
•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 the ignition switch to OFF.
2)Disconnect the connector from engine cool-
ant temperature sensor.
3)Measure the 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 the ignition switch to ON.
2)Measure the voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground ( − − − − ):
Check
Is the value 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
EN-129
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
(B21)
• Poor contact in
joint connector
(B83) or (B122)
Go to step 3.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 4.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
No