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 (−):
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Is the voltage 10 V or more?
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Repair the power supply circuit.
NOTE:
In this case, repair the following item:
• Open or ground short circuit of harness between fuel pump relay and fuel pump control unit
• Poor contact of fuel pump relay connector
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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:
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Is the resistance less than 5 Ω?
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Repair the open circuit in harness between fuel pump control unit and chassis ground.
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3.CHECK HARNESS BETWEEN FUEL PUMP CONTROL UNIT AND FUEL PUMP CONNECTOR.
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:
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Is the resistance less than 1 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following items.
• Open circuit in harness between fuel pump control unit and fuel pump
• Poor contact of coupling connector
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4.CHECK HARNESS BETWEEN FUEL PUMP CONTROL UNIT AND FUEL PUMP CONNECTOR.
Measure the resistance between fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 7 — Chassis ground:
(R122) No. 6 — Chassis ground:
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Is the resistance 1 MΩ or more?
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Repair the ground short circuit of harness between fuel pump control unit and fuel pump.
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5.CHECK HARNESS BETWEEN ECM AND FUEL PUMP CONTROL UNIT.
1) Disconnect the connectors from the ECM.
2) Measure the resistance of the harness between the ECM and fuel pump control unit.
Connector & terminal
(B135) No. 33 — (R122) No. 9:
(B136) No. 12 — (B122) No. 8:
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Is the resistance less than 1 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following item:
• Open circuit between the ECM and fuel pump control unit
• Poor contact of coupling connector
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6.CHECK HARNESS BETWEEN ECM AND FUEL PUMP CONTROL UNIT.
Measure the resistance between fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 9 — Chassis ground:
(R122) No. 8 — Chassis ground:
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Is the resistance 1 MΩ or more?
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Repair the ground short circuit of harness between ECM and fuel pump control unit.
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7.CHECK FOR POOR CONTACT.
Check for poor contact of ECM and fuel pump control unit connector.
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Is there poor contact of ECM or fuel pump control unit connector?
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Repair the poor contact of ECM or fuel pump control unit connector.
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8.CHECK EXPERIENCE OF RUNNING OUT OF FUEL.
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Has the vehicle experienced running out of fuel?
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Finish the diagnosis.
NOTE:
DTC may be recorded as a result of fuel pump idling while running out of fuel.
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Replace the fuel pump control unit. 
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