Subaru Legacy 2003 Service Manual page 668

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure voltage between ECM connector and
chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the specified
value?
3 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure voltage between ECM connector and
chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
Is the measured value less than the specified
value?
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM and chassis
ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
Does the measured value change within the
specified range?
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure voltage between TCM and chassis
ground.
Connector & terminal
(B56) No. 21 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the specified
value?
6 CHECK POOR CONTACT.
Check poor contact in TCM connector.
Is there poor contact in TCM connector?
Value
10 V
4 V
1 V
1 V - 4 V
4 V
There is poor contact.
EN(H4SO)-271
ENGINE (DIAGNOSTICS)
Yes
Repair battery Go to step 2.
short circuit in har-
ness between
ECM and TCM
connector. After
repair, replace
ECM. <Ref. to
FU(H4SO)-45,
Engine Control
Module.>
Go to step 5. Go to step 3.
Repair poor con- Go to step 4.
tact in ECM con-
nector.
Even if MI lights Contact SUBARU
up, the circuit has distributor service.
returned to a nor-
NOTE:
mal condition at
Inspection by DTM
this time.
is required,
cause
NOTE:
In this case, repair cause is deteriora-
the following: tion of
• Poor contact in parts.
ECM connector
• Poor contact in
TCM connector
Go to step 6. Repair open circuit
in harness
between ECM and
TCM connector.
Repair poor con- Check TCM power
tact in TCM con- supply line and
nector. grounding line.
No
be-
probable
multiple