Subaru Legacy 2005 Service Manual page 1873

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK POWER SUPPLY CIRCUIT TO FUEL
PUMP CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel pump
control unit.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pump
control unit and chassis ground.
Connector & terminal
(R122) No. 10 (+) — Chassis ground (
2 CHECK GROUND CIRCUIT OF FUEL PUMP
CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between fuel pump control unit and chassis
ground.
Connector & terminal
(R122) No. 5 — Chassis ground:
3 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from fuel pump.
2) Measure the resistance of harness
between fuel pump control unit and fuel pump
connector.
Connector & terminal
(R122) No. 7 — (R58) No. 5:
(R122) No. 6 — (R58) No. 6:
4 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
Measure the resistance of harness between
fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 7 — Chassis ground:
(R122) No. 6 — Chassis ground:
Check
Is the voltage more than 10 V? Go to step 2.
−
):
Is the resistance less than 5
Ω?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
EN(H6DO)(diag)-177
ENGINE (DIAGNOSTICS)
Yes
Repair the power
supply circuit.
NOTE:
In this case, repair
the following:
• Open or ground
short circuit of har-
ness between fuel
pump relay and
fuel pump control
unit
• Poor contact in
fuel pump control
unit connector
• Poor contact in
fuel pump relay
connector
Go to step 3. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit
between fuel pump
control unit and
chassis ground
• Poor contact in
fuel pump control
unit connector
Go to step 4. Repair the open
circuit between
fuel pump control
unit and fuel
pump.
Go to step 5. Repair the ground
short circuit
between fuel pump
control unit and
fuel pump.
No