Subaru Legacy 2003 Service Manual page 863

DIAGNOSTICS FOR ENGINE STARTING FAILURE
ENGINE (DIAGNOSTICS)
1 CHECK MAIN RELAY.
1) Turn the ignition switch to OFF.
2) Remove main relay.
3) Connect battery to main relay terminals No.
1 and No. 2.
4) Measure resistance between main relay
terminals.
Terminals
No. 3 — No. 5:
No. 4 — No. 6:
Is the measured value less than the speci-
fied value?
2 CHECK GROUND CIRCUIT OF ECM.
1) Disconnect connector from ECM.
2) Measure resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 21 — Chassis ground:
(B136) No. 22 — Chassis ground:
(B135) No. 6 — Chassis ground (only
LHD model):
(B135) No. 25 — Chassis ground (only
MT model):
(B134) No. 27 — Chassis ground:
(B134) No. 8 — Chassis ground:
(B134) No. 7 — Chassis ground:
Is the measured value less than the speci-
fied value?
3 CHECK INPUT VOLTAGE OF ECM.
Measure voltage between ECM connector and
chassis ground.
Connector & terminal
(B136) No. 9 (+) — Chassis ground (–):
Does the measured value exceed the specified
value?
4 CHECK INPUT VOLTAGE OF ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 7 (+) — Chassis ground (–):
Does the measured value exceed the spec-
ified value?
5 CHECK HARNESS BETWEEN ECM AND
MAIN RELAY CONNECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between ECM and
chassis ground.
Connector & terminal
(B135) No. 19 — Chassis ground:
Does the measured value exceed the spec-
ified value?
Step
EN(H4SOw/oOBD)-44
Value
10 Ω
5 Ω
10 V
10 V
1 MΩ
Yes
Go to step 2. Replace main
relay.
Go to step 3. Repair open circuit
in harness
between ECM
connector and
engine grounding
terminal.
Go to step 4. Repair open or
ground short cir-
cuit of power sup-
ply circuit.
Go to step 5. Repair open or
ground short cir-
cuit of power sup-
ply circuit.
Go to step 6. Repair ground
short circuit in har-
ness between
ECM connector
and main relay
connector, then
replace ECM.
No