Subaru 2002 IMPREZA Service Manual page 1247

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
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 or
the OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(TURBO)-34, 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 OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 4 (+) — Chassis ground ( − − − − ):
(B137) No. 5 (+) — Chassis ground ( − − − − ):
Check
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 volt-
age meter?
EN(TURBO)-87
ENGINE (DIAGNOSTICS)
Yes
Replace the ECM. END
<Ref. to
FU(TURBO)-49,
Engine Control
Module.>
Repair the battery END
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
No