Subaru Legacy 2004 Service Manual page 509

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
(B135) No. 3 (+) — Chassis ground (
2 CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1) Turn the ignition switch to OFF.
2) Repair the battery short circuit in harness
between ECM and front oxygen (A/F) sensor
connector.
3) Turn the ignition switch to ON.
4) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.0)(diag)-25, Subaru Select Mon-
itor.>
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 2 (+) — Chassis ground (
(B135) No. 3 (+) — Chassis ground (
Check
Is the voltage more than 8 V?
"
):
"
):
Is the current more than 2.3 A? Replace the ECM.
Does the voltage change by
shaking the ECM harness and
connector?
"
):
"
):
EN(H4SO 2.0)(diag)-77
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Go to step 3.
END.
<Ref. to FU(H4SO
2.0)-34, Engine
Control Module
(ECM).>
Repair the battery END.
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
No