Subaru IMPREZA 2004 Service Manual page 761

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Remove the generator.
3)Disconnect the connector from engine cool-
ant temperature sensor.
4)Measure the voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground ( − − − − ):
2 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 ( − − − − ):
3 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
Measure the voltage between engine coolant
temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 1 (+) — Engine ground ( − − − − ):
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 4 V?
EN(H4SOw/oOBD)(diag)-65
Check
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 4.
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2.
Go to step 3.
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and engine
coolant tempera-
ture sensor con-
nector
• Poor contact in
engine coolant
temperature sen-
sor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
(B21)