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Fuel Pump Circuit

CAUTION: After repairing or replacing the defective part, perform the Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM: 

Fig 1: Fuel Pump - Wiring Diagram
G05017531
DIAGNOSIS PROCEDURE

Step Check Yes No
1 CHECK OPERATING SOUND OF FUEL PUMP. 
Check if the fuel pump operates for two seconds when turning the ignition switch to ON.
NOTE: Fuel pump operation can also be executed using Subaru Select Monitor.
Refer to "Compulsory Valve Operation Check Mode" for procedures. < Ref. to COMPULSORY VALVE OPERATION CHECK MODE . >
 Does the fuel pump emit operating sound? Check the fuel injector circuit. < Ref. to FUEL INJECTOR CIRCUIT , Diagnostics for Engine Starting Failure. > Go to step 2. 
2 CHECK GROUND CIRCUIT OF FUEL PUMP. 
  1. Turn the ignition switch to OFF.
  2. Remove the fuel pump access hole lid.
  3. Disconnect the connector from fuel pump.
  4. Measure the resistance of harness connector between fuel pump and chassis ground.

    Connector & terminal 

    (R58) No. 6 - Chassis ground: 

 Is the resistance less than 5 Ω? Go to step 3.  Repair the harness and connector.
NOTE: In this case, repair the following item: Open circuit in harness between fuel pump connector and chassis grounding terminal
3 CHECK POWER SUPPLY TO FUEL PUMP. 
  1. Turn the ignition switch to ON.
  2. Measure the voltage of power supply circuit between fuel pump connector and chassis ground.

    Connector & terminal 

    (R58) No. 5 (+) - Chassis ground (-): 

 Is the voltage more than 10 V? Replace the fuel pump. < Ref. to FUEL PUMP . > Go to step 4. 
4 CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Measure the resistance of harness connector between fuel pump and fuel pump relay.

    Connector & terminal 

    (R58) No. 5 - (B362) No. 2: 

 Is the resistance less than 1 Ω? Go to step 5.  Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between fuel pump connector and chassis grounding terminal
  • Poor contact of coupling connector
5 CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY CONNECTOR. 
Measure the resistance of harness between fuel pump and fuel pump relay connector.
Connector & terminal 
(R58) No. 5 - Chassis ground: 		 Is the resistance more than 1 MΩ? Go to step 6.  Repair the short circuit of harness between fuel pump and fuel pump relay connector.
6 CHECK FUEL PUMP RELAY. 
  1. Disconnect the connectors from fuel pump relay and main relay.
  2. Remove the fuel pump relay and main relay with bracket.
  3. Connect the battery to fuel pump relay connector terminals No. 3 and No. 4.
  4. Measure the resistance between connector terminals of fuel pump relay.

    Terminals No. 1 - No. 2: 

 Is the resistance less than 10 Ω? Go to step 7.  Replace the fuel pump relay. < Ref. to FUEL PUMP . >
7 CHECK HARNESS BETWEEN ECM AND FUEL PUMP RELAY CONNECTOR. 
  1. Disconnect the connectors from ECM.
  2. Measure the resistance of harness between ECM and fuel pump relay connector.

    Connector & terminal 

    (B136) No. 12 - (B362) No. 3: 

 Is the resistance less than 1 Ω? Go to step 8.  Repair the open circuit of harness between ECM and fuel pump relay connector.
8 CHECK POOR CONTACT. 
Check poor contact of ECM connector.		 Is there poor contact in ECM connector? Repair the poor contact of ECM connector. Check the fuel injector circuit. < Ref. to FUEL INJECTOR CIRCUIT , Diagnostics for Engine Starting Failure. >
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