Subaru 2009 IMPREZA Service Manual page 1386

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 connector 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 between fuel pump
control unit connector and chassis ground.
Connector & terminal
(R122) No. 7 — Chassis ground:
(R122) No. 6 — Chassis ground:
Check
Is the voltage 10 V or more?
Is the resistance less than 5 ? Go to step 3.
Is the resistance less than 1 ? Go to step 4.
Is the resistance 1 M or
more?
EN(H4DOTC)(diag)-165
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2. Repair the power
supply circuit.
NOTE:
In this case, repair
the following item:
• Open circuit or
short
ground in harness
between fuel pump
relay
and fuel pump con-
trol unit connector
• Poor contact of
fuel pump control
unit connector
• Poor contact of
fuel pump
connector
• Poor contact of
coupling connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
fuel pump control
unit connector and
chassis ground
• Poor contact of
fuel pump control
unit connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
fuel pump control
unit connector and
fuel pump connec-
tor
• Poor contact of
coupling connector
Go to step 5. Repair the short
circuit to ground in
harness between
fuel pump control
unit connector and
fuel pump connec-
tor.
circuit to
connector
relay