Subaru 2009 IMPREZA Service Manual page 551

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
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)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
2 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 34 — Chassis ground:
Check
Is the engine coolant tempera-
ture 150°C (302°F) or higher?
Is the resistance 1 M or
more?
EN(H4SO)(diag)-134
Yes No
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.
Replace the Repair short cir-
engine coolant cuit in harness to
temperature sen- ground between
sor. <Ref. to ECM and engine
FU(H4SO)-25, coolant tempera-
Engine Coolant ture sensor con-
Temperature Sen- nector.
sor.>