Subaru LEGACY 2003 Service Manual page 38

ENGINE MALFUNCTION INDICATOR LAMP (MIL)
ENGINE (DIAGNOSTICS)
1 CHECK STATUS OF CHECK ENGINE MAL-
FUNCTION INDICATOR LAMP (MIL).
1) Turn ignition switch to OFF.
2) Disconnect test mode connector.
3) Turn ignition switch to ON.
Does the MIL come on?
2 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between test mode connector
and chassis ground.
Connector & terminal
(B75) No. 1 (+) — Chassis ground ( − − − − ):
Is the measured value less than the specified
value?
3 CHECK HARNESS BETWEEN ECM AND
TEST MODE CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between
ECM and test mode connector.
Connector & terminal
(B135) No. 14 — (B75) No. 1:
Is the measured value less than the speci-
fied value?
4 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
5 CHECK HARNESS BETWEEN TEST MODE
CONNECTOR AND CHASSIS GROUND.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between
test mode connector and chassis ground.
Connector & terminal
(B76) No. 1 — Chassis ground:
Is the measured value less than the speci-
fied value?
6 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
Step
EN(H4SOw/oOBD)-36
Value
MIL illuminates.
1 V
1 Ω
There is poor contact.
1 Ω
There is poor contact.
Yes
Go to step 2. Repair the MIL cir-
cuit. <Ref. to
EN(H4SOw/
oOBD)-31,
CHECK ENGINE
MALFUNCTION
INDICATOR
LAMP (MIL)
DOES NOT
COME ON.,
Engine Malfunc-
tion Indicator
Lamp (MIL).>
Go to step 3. Go to step 5.
Go to step 4. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and test
mode connector
Repair poor con- Replace ECM.
tact in ECM con- <Ref. to
nector. FU(H4SOw/
oOBD)-42, Engine
Control Module.>
Go to step 6. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
test mode connec-
tor and chassis
ground
Repair poor con- Replace ECM.
tact in ECM con- <Ref. to
nector. FU(H4SOw/
oOBD)-42, Engine
Control Module.>
No