Subaru Legacy 2003 Service Manual page 500

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK INPUT SIGNAL FOR ECM.
Measure voltage between ECM connector and
chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the specified
value?
2 CHECK CURRENT DATA.
1) Turn ignition switch to OFF.
2) Repair battery short circuit in harness
between ECM and rear oxygen sensor con-
nector.
3) Turn ignition switch to ON.
4) Read data of rear oxygen sensor heater
current using Subaru Select Monitor or the
OBD-II general scan tool.
Does the measured value exceed the spec-
ified value?
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)-32, Subaru Select Moni-
tor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
Value
8 V
7 A
There is poor contact.
EN(H4SO)-103
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Go to step 3.
Replace ECM. END
<Ref. to
FU(H4SO)-45,
Engine Control
Module.>
Repair poor con- END
tact in ECM con-
nector.
No