Subaru Legacy 2003 Service Manual page 902

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
7 CHECK HARNESS BETWEEN ECM AND OX-
YGEN SENSOR.
1) Ignition switch to ON.
2) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 7 (+) — Chassis ground (–):
Does the measured value exceed the spec-
ified value?
8 CHECK INPUT VOLTAGE FOR ECM.
1) Turn ignition switch OFF.
2) Warm up engine until coolant temperature
exceed 70°C (158°F) and idle.
3) Set plus (+) probe to ECM connector termi-
nal, and set minus (−) probe to chassis
ground.
Connector & terminal
(B136) No. 7 (+) — Chassis ground ( − − − − ):
4) Measure voltage between ECM and chas-
sis ground.
Is the measured waveform standard?
9 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
Value
0.2 V
←
0.1 1 V
→
There is poor contact.
EN(H4SOw/oOBD)-83
ENGINE (DIAGNOSTICS)
Yes
Go to step 8. Repair battery
short circuit
between ECM and
oxygen sensor.
Go to step 9. Replace oxygen
sensor.
Replace oxygen Replace ECM.
sensor connector. <Ref. to
FU(H4SOw/
oOBD)-42, Engine
Control Module.>
No