Subaru Forester 2004 Service Manual page 98

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or the OBD-II general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to EN(H4DOTC
2.5)-27, Subaru Select Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.
2 CHECK HARNESS BETWEEN ENGINE
COOLANT TEMPERATURE SENSOR AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the engine
coolant temperature sensor.
3) Measure the voltage between engine cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — 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 cool-
ant temperature sensor connector and engine
ground.
Connector & terminal
(E8) No. 2 (+) — Engine ground (
4 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. 2 (+) — Engine ground (
Check
Is the value less than −40°C
(−40°F)?
Is the voltage more than 10 V? Repair battery
−
):
Is the voltage more than 10 V? Repair battery
−
):
Is the voltage more than 4 V?
−
):
EN(H4DOTC 2.5)-97
ENGINE (DIAGNOSTIC)
Yes
Go to step 2. Repair the poor
contact.
NOTE:
In this case repair
the following:
• Poor contact in
engine coolant tem-
perature sensor
• Poor contact in
ECM
• Poor contact in
coupling connector
• Poor contact in
joint connector
Go to step 3.
short circuit in har-
ness between ECM
and engine coolant
temperature sen-
sor connector.
Go to step 4.
short circuit in har-
ness between
ECM and engine
coolant tempera-
ture sensor con-
nector.
Go to step 5. 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
• Poor contact in
joint connector
No