Subaru LEGACY 2004 Service Manual page 345

ENGINE (DIAGNOSTICS)
Step
1 CHECK MAIN RELAY.
1) Turn the ignition switch to OFF.
2) Remove the main relay.
3) Connect the battery to main relay terminals
No. 1 and No. 2.
4) Measure the resistance between main relay
terminals.
Terminals
No. 3 — No. 5:
No. 4 — No. 6:
2 CHECK GROUND CIRCUIT FOR ECM.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness
between ECM and chassis ground.
Connector & terminal
(B134) No. 2 — Chassis ground:
(B134) No. 7 — Chassis ground:
(B135) No. 5 — Chassis ground:
(B135) No. 6 — Chassis ground:
(B136) No. 1 — Chassis ground:
(B136) No. 2 — Chassis ground:
(B136) No. 5 — Chassis ground:
(B136) No. 6 — Chassis ground:
(B137) No. 1 — Chassis ground:
3 CHECK INPUT VOLTAGE OF ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 7 (+) — Chassis ground (
4 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 13 (+) — Chassis ground (
5 CHECK INPUT VOLTAGE OF MAIN RELAY.
Measure the voltage between main relay con-
nector and chassis ground.
Connector & terminal
(B47) No. 1 (+) — Chassis ground (
6 CHECK INPUT VOLTAGE OF ECM.
1) Connect the connectors to ECM and main
relay.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 14 (+) — Chassis ground (
7 CHECK INPUT VOLTAGE OF MAIN RELAY.
Measure the voltage between main relay con-
nector and chassis ground.
Connector & terminal
(B47) No. 5 (+) — Chassis ground (
(B47) No. 6 (+) — Chassis ground (
Diagnostics for Engine Starting Failure
Is the resistance less than 10
Ω?
Is the resistance less than 5
Ω?
Is the voltage more than 10 V? Go to step 4.
−
):
Is the voltage more than 10 V? Go to step 5.
−
):
Is the voltage more than 10 V? Go to step 6.
−
):
Is the voltage more than 10 V? Go to step 7.
−
):
Is the voltage more than 10 V? Go to step 8.
−
):
−
):
EN(H4SO 2.0)(diag)-56
Check
Go to step 2.
Go to step 3.
Yes No
Replace the main
relay.
Repair the open
circuit in harness
between ECM
connector and
engine grounding
terminal.
Repair the open or
ground short cir-
cuit of power sup-
ply circuit.
Repair the open or
ground short cir-
cuit of power sup-
ply circuit.
Repair the open
circuit in harness
between ECM
connector and
main relay connec-
tor.
Repair the open or
ground short cir-
cuit in harness
between ECM
connector and
main relay connec-
tor.
Repair the open or
ground short cir-
cuit in harness of
power supply cir-
cuit.