Diagnostic Procedure With Diagnostic Trouble Code (Dtc) - Subaru Legacy 2002 Service Manual

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Engine (DIAGNOSTICS)
No.
2 CHECK GROUND CIRCUIT OF ECM.
Measure resistance of harness between ECM
connector and chassis ground.
Connector & terminal
(B137) No. 31 — Chassis ground:
(B137) No. 21 — Chassis ground:
(B137) No. 8 — Chassis ground:
(B137) No. 9 — Chassis ground:
3 CHECK CURRENT DATA.
1) Start engine
2) Read data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
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(H6)-38, Subaru Select Monitor.>
¼ OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
4 CHECK OUTPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 4 (+) — Chassis ground (−):
5 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 4 (+) — Chassis ground (−):
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 5 (+) — Chassis ground (−):
7 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 5 (+) — Chassis ground (−):
Step
Is the resistance less than
5 Ω?
Is the value more than 0.2
A?
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 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?
EN(H6)-96
Check Yes
Go to step 6.
Repair poor con-
tact in connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Poor contact in
front oxygen (A/F)
sensor connector
¼ Poor contact in
ECM connector
Go to step 6.
Repair poor con-
tact in ECM con-
nector.
Go to step 8.
Repair poor con-
tact in ECM con-
nector.
No
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
ECM and engine
ground terminal
¼ Poor contact in
ECM connector
Poor contact in
coupling connec-
tor
Go to step 4.
Go to step 5.
Go to step 6.
Go to step 7.
Go to step 8.