Inspection Procedure 20: Fuel pump system












OPERATION



  • The battery voltage is applied to the fuel pump relay (1) (terminal No. 3) from the ignition switch and is earthed to the vehicle body from the fuel pump relay (1) (terminal No. 2).
  • The battery voltage is applied to the fuel pump relay (1) (terminal No. 4) and to the fuel pump relay (2) (terminal No. 1) from the fuel pump relay (1) (terminal No. 1).
  • The battery voltage is applied to the fuel pump relay (2) (terminal No. 3) from the ignition switch. The engine-A/T-ECU (terminal No. 16) makes the power transistor in the unit be in ON position and makes currents go on the fuel pump relay (2) coil, and that makes the relay be in ON position.
  • When the fuel pump relay (2) is in ON position, the battery voltage is supplied to the fuel pump from the fuel pump relay (2) (terminal No. 4).

FUNCTION



  • When the ignition switch ON signal is input to the engine-A/T-ECU, the engine-A/T-ECU places the fuel pump relay in the ON position. Accordingly, the battery voltage is supplied to the fuel pump.

PROBABLE CAUSES



  • Failed fuel pump relay
  • Failed fuel pump
  • Open/short circuit in fuel pump drive circuit or loose connector contact
  • Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE
note
    *1: L.H. drive vehicles
    *2: R.H. drive vehicles

STEP 1. Connector check: D-417 fuel pump relay (1) connector and D-413 fuel pump relay (2) connector

Q. Are the check results normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. Check fuel pump relay.

  • Fuel pump relay, continuity check (Refer to ).

Q. Is the check result normal?
Go to Step 3 .
Replace the fuel pump relay.

STEP 3. Perform resistance measurement at D-417 fuel pump relay (1) connector.

  • Remove relay, and measure at junction block side.
  • Resistance between terminal No. 2 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 4 .

    Check intermediate connector D-405, and repair if necessary. If intermediate connector is normal, check and repair harness between D-417 (terminal No. 2) fuel pump relay (1) connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 4. Perform voltage measurement at D-417 fuel pump relay (1) connector.

  • Remove relay, and measure at junction block side.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 6 .
Go to Step 5 .

STEP 5. Connector check: D-309 ignition switch connector

Q. Is the check result normal?


    Check intermediate connector D-403, and repair if necessary. If intermediate connector is normal, check and repair harness between D-417 (terminal No. 3) fuel pump relay (1) connector and D-309 (terminal No. 2) ignition switch connector.

    • Check power supply line for open circuit and damage.
Repair or replace the connector.

STEP 6. Perform voltage measurement at D-417 fuel pump relay (1) connector.

  • Remove relay, and measure at junction block side.
  • Voltage between terminal No. 4 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 7 .

    Check intermediate connectors D-241 and D-401, and repair if necessary. If intermediate connectors are normal, check and repair harness between D-417 (terminal No. 4) fuel pump relay (1) connector and battery.

    • Check power supply line for open/short circuit.

STEP 7. Perform voltage measurement at D-413 fuel pump relay (2) connector.

  • Remove relay, and measure at junction block side.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 9 .
Go to Step 8 .

STEP 8. Connector check: D-309 ignition switch connector

Q. Is the check result normal?

    Check intermediate connector D-403, and repair if necessary. If intermediate connector is normal, check and repair harness between D-309 (terminal No. 2) ignition switch connector and D-413 (terminal No. 3) fuel pump relay (2) connector.

    • Check power supply line for open circuit.
Repair or replace the connector.

STEP 9. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 10 .
Repair or replace the connector.

STEP 10. Perform voltage measurement at D-212 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 16 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 11 .

    Check intermediate connectors D-231 and D-405, and repair if necessary. If intermediate connectors are normal, check and repair harness between D-413 (terminal No. 2) fuel pump relay (2) connector and D-212 (terminal No. 16) engine-A/T-ECU connector.

    • Check earthing line for open/short circuit.

STEP 11. Connector check: E-10 fuel pump connector

Q. Is the check result normal?
Go to Step 12 .
Repair or replace the connector.

STEP 12. Perform voltage measurement at E-10 fuel pump connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Using a jumper wire, connect D-212 (terminal No. 16) engine-A/T-ECU connector and earth.
  • Voltage between terminal No. 5 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 15 .
Go to Step 13 .

STEP 13. Check harness between D-417 (terminal No. 1) fuel pump relay (1) connector and D-413 (terminal No. 1) fuel pump relay (2) connector.

  • Check power supply line for open/short circuit.

Q. Is the check result normal?
Go to Step 14 .
Repair the damaged harness wire.

STEP 14. Check harness between D-413 (terminal No. 4) fuel pump relay (2) connector and E-10 (terminal No. 5) fuel pump connector.
note Before checking harness, check intermediate connectors D-409*1 or D-422*2, D-220*1 and E-09, and repair if necessary.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Replace the engine-A/T-ECU.
Repair the damaged harness wire.

STEP 15. Perform resistance measurement at E-10 fuel pump connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 4 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 16 .

    Check intermediate connector E-09, and repair if necessary. If intermediate connector is normal, check and repair harness between E-10 (terminal No. 4) fuel pump connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 16. Connector check: D-309 ignition switch connector

Q. Is the check result normal?
Go to Step 17 .
Repair or replace the connector.

STEP 17. Check harness between D-309 (terminal No. 2) ignition switch connector and D-417 (terminal No. 3) fuel pump relay (1) connector.
note Before checking harness, check intermediate connector D-403, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 18 .
Repair the damaged harness wire.

STEP 18. Check harness between battery and D-417 (terminal No. 4) fuel pump relay (1) connector.
note Before checking harness, check intermediate connectors D-241 and D-401, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 19 .
Repair the damaged harness wire.

STEP 19. Check harness between D-417 (terminal No. 1) fuel pump relay (1) connector and D-413 (terminal No. 1) fuel pump relay (2) connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 20 .
Repair the damaged harness wire.

STEP 20. Check harness between D-309 (terminal No. 2) ignition switch connector and D-413 (terminal No. 3) fuel pump relay (2) connector.
note Before checking harness, check intermediate connector D-403, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 21 .
Repair the damaged harness wire.

STEP 21. Check harness between D-413 (terminal No. 4) fuel pump relay (2) connector and E-10 (terminal No. 5) fuel pump connector.
note Before checking harness, check intermediate connectors D-220*1, D-409*1 or D-422*2 and E-09, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 22 .
Repair the damaged harness wire.

STEP 22. Check harness between D-413 (terminal No. 2) fuel pump relay (2) connector and D-212 (terminal No. 16) engine-A/T-ECU connector.
note Before checking harness, check intermediate connectors D-231 and D-405, and repair if necessary.

  • Check earthing line for damage.

Q. Is the check result normal?
Replace the fuel pump.
Repair the damaged harness wire.