Subaru Forester 2004 Service Manual page 126

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. 6 — (R58) No. 4:
(R122) No. 7 — (R58) No. 1:
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. 6 — Chassis ground:
(R122) No. 7 — Chassis ground:
5 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance in harness
between fuel pump control unit and ECM con-
nector.
Connector & terminal
(R122) No. 8 — (B137) No. 28:
(R122) No. 9 — (B135) No. 27:
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?
Is the resistance less than 1
Ω?
EN(H4DOTC 2.5)-125
ENGINE (DIAGNOSTIC)
Yes
Repair the power
supply circuit.
NOTE:
In this case repair
the following:
• Open or ground
short circuit in 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 harness
and connector.
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 open circuit
between fuel pump
control unit and
fuel pump.
Go to step 5. Repair ground
short circuit
between fuel pump
control unit and
fuel pump.
Go to step 6. Repair the harness
and connector.
NOTE:
In this case repair
the following:
• Open circuit
between fuel pump
control unit and
ECM.
• Poor contact in
fuel pump control
unit and ECM con-
nector
No