Subaru Impreza 2003 Service Manual page 1432

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
3 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between TCM and chas-
sis ground.
Connector & terminal
(B56) No. 21 (+) — Chassis ground ( − − − − ):
6 CHECK POOR CONTACT.
Check poor contact in TCM connector.
Check
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 4 V?
Is the voltage less than 1 V?
Does the voltage change
between 1 and 4 V while moni-
toring the value with voltage
meter?
Is the voltage more than 4 V?
Is there poor contact in TCM
connector?
EN(H4DOTC)-256
Yes
Go to step 2.
short circuit in har-
ness between
ECM and TCM
connector. After
repair, replace the
ECM. <Ref. to
FU(H4DOTC)-49,
Engine Control
Module (ECM).>
Go to step 5. Go to step 3.
Repair the poor Go to step 4.
contact in ECM
connector.
Even if malfunc- Contact your Sub-
tion indicator light aru distributor ser-
lights up, the cir- vice.
cuit has returned
NOTE:
to a normal condi-
Inspection by DTM
tion at 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 the open
circuit in harness
between ECM and
TCM connector.
Repair the poor Check the TCM
contact in TCM power supply line
connector. and grounding
line.
No
be-
probable
multiple