Subaru IMPREZA GD 2007 Series Manual page 230

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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 general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(diag)-32, Subaru Select Monitor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
2 CHECK POOR CONTACT.
Repair any poor contact between the ECM and
engine coolant temperature sensor connectors.
3 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and engine coolant temperature sensor.
3) Measure the resistance of the harness
between the ECM and engine coolant tempera-
ture sensor connector.
Connector & terminal
(B134) No. 34 — (E8) No. 2:
(B134) No. 29 — (E8) No. 1:
4 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 34 (+) — Chassis ground (–):
Check
Is the engine coolant tempera-
ture less than –40°C (–40°F) ?
Is there poor contact in the
ECM or engine coolant temper-
ature sensor connectors?
Is the resistance less than 1 Ω? Go to step 4.
Is the voltage 5 V or more?
EN(H4SO)(diag)-121
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2. Even if the malfunc-
tion indicator light
illuminates, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the fault con-
dition, and
reperform the
check.
NOTE:
In this case, there
may be a tempo-
rary connector
contact failure.
Repair any poor Go to step 3.
contact between
the ECM and
engine coolant
temperature sen-
sor connectors.
Repair the open
circuit of the har-
ness between the
ECM and engine
coolant tempera-
ture sensor con-
nector.
Repair the short Replace the
circuit to power in engine coolant
the harness temperature sen-
between the ECM sor. <Ref. to
and engine coolant FU(H4SO)-22,
temperature sen- Engine Coolant
sor connector. Temperature Sen-
sor.>