Subaru Legacy 2002 Service Manual page 610

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground
(−):
2 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 22 (+) — Chassis ground
(−):
3 CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1) Turn ignition switch to OFF.
2) Repair battery short circuit in harness
between ECM and front oxygen (A/F) sensor
connector.
3) Turn ignition switch to ON.
4) Read data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
the OBD-II general scan tool.
NOTE:
¼ Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
¼ OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground
(−):
5 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 22 (+) — Chassis ground
(−):
Step
Is the voltage more than 8
V?
Is the voltage more than 8
V?
Is the value more than 2.3
A?
Does the voltage change
more than 8 V by shaking
harness and connector of
ECM while monitoring the
value with voltage meter?
Does the voltage change
more than 8 V by shaking
harness and connector of
ECM while monitoring the
value with voltage meter?
EN-93
Check Yes
Go to step 3.
Go to step 3.
Replace ECM.
<Ref. to FU-51,
Engine Control
Module.>
Repair battery
short circuit in
harness between
ECM and front
oxygen (A/F) sen-
sor connector.
Repair battery
short circuit in
harness between
ECM and front
oxygen (A/F) sen-
sor connector.
Engine (Diagnostics)
No
Go to step 2.
Go to step 4.
END
Go to step 5.
END