Subaru Legacy 2002 Service Manual page 607

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Engine (Diagnostics)
No.
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 22 (+) — Chassis ground
(−):
7 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground
(−):
8 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground
(−):
9 CHECK FRONT OXYGEN (A/F) SENSOR.
1) Turn ignition switch to OFF.
2) Measure resistance between front oxygen
(A/F) sensor connector terminals.
Terminals
No. 2 — No. 5:
Step
Does the voltage change
less than 1.0 V by shaking
harness and connector of
ECM while monitoring the
value with voltage meter?
Is the voltage less than 1.0
V?
Does the voltage change
less than 1.0 V by shaking
harness and connector of
ECM while monitoring the
value with voltage meter?
Is the resistance less than
10 Ω?
EN-90
Check Yes
Repair poor con-
tact in ECM con-
nector.
Go to step 9.
Repair poor con-
tact in ECM con-
nector.
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open or ground
short circuit in
harness between
front oxygen (A/F)
sensor and ECM
connector
¼ Poor contact in
front oxygen (A/F)
sensor connector
¼ Poor contact in
ECM connector
No
Go to step 7.
Go to step 8.
Go to step 9.
Replace front oxy-
gen (A/F) sensor.
<Ref. to FU-47,
Front Oxygen
(A/T) Sensor.>