Inspection Procedure 25: Fuel Pump System














OPERATION



  • The fuel pump drive power is supplied from engine control relay (terminal No. 2) to fuel pump relay (C-307 ETACS-ECU connector terminal No. 1) in the ETACS-ECU.
  • The battery voltage is applied by the ignition switch to the fuel pump coil (C-317 ETACS-ECU connector terminal No. 6) in the ETACS-ECU. The engine-ECU turns on the relay by turning ON the power transistor in the unit so as to conduct power to the fuel pump relay coil (via the C-304 ETACS-ECU connector terminal No. 11).
  • When the fuel pump relay is turned ON, the battery voltage will be supplied from the fuel pump relay (C-314 ETACS-ECU connector terminal No. 1) to the fuel pump (terminal No. 5).

FUNCTION



  • When the ignition switch ON signal is inputted into the engine-ECU, the engine-ECU turns ON the fuel pump relay. This causes the battery voltage to be supplied to the fuel pump.

PROBABLE CAUSES



  • Failed fuel pump relay in the ETACS-ECU
  • Failed fuel pump
  • Open/short circuit or harness damage in the fuel pump drive circuit or loose connector contact.
  • Failed engine-ECU

DIAGNOSIS PROCEDURE


STEP 1. Connector check: C-304, C-307, C-314 and C-317 ETACS-ECU connectors


Q. Are the check results normal?

Go to Step 2 .
Repair or replace the connector.

STEP 2. Check fuel pump relay.



  • Perform continuity test in fuel pump relay (Refer to ).

Q. Is the check result normal?

Go to Step 3 .
Replace the ETACS-ECU.

STEP 3. Connector check: B-18 engine-ECU connector


Q. Is the check result normal?

Go to Step 4 .
Repair or replace the connector.

STEP 4. Perform voltage measurement at B-18 engine-ECU connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 25 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 5 .

    Check and repair harness between B-18 (terminal No. 25) engine-ECU connector and C-304 (terminal No. 11) ETACS-ECU connector.

    • Check output line for open/short circuit.

STEP 5. Perform voltage measurement at C-307 ETACS-ECU connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 7 .
Go to Step 6 .

STEP 6. Connector check: A-33X engine control relay connector


Q. Is the check result normal?


    Check and repair harness between A-33X (terminal No. 2) engine control relay connector and C-307 (terminal No. 1) ETACS-ECU connector.

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

STEP 7. Connector check: D-22 fuel pump connector


Q. Is the check result normal?

Go to Step 8 .
Repair or replace the connector.

STEP 8. Check fuel pump operations.



  • Check fuel pump operations (Refer to ).

Q. Is the check result normal?

Go to Step 9 .
Replace the fuel pump and gage unit.

STEP 9. Perform resistance measurement at D-22 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 10 .

    Check and repair harness between D-22 (terminal No. 4) fuel pump connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 10. Check harness between C-314 (terminal No. 1) ETACS-ECU connector and D-22 (terminal No. 5) fuel pump connector.



  • Check power supply line for open/short circuit.

Q. Is the check result normal?

Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Check harness between B-18 (terminal No. 25) engine-ECU connector and C-304 (terminal No. 11) ETACS-ECU connector.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 12 .
Repair the damaged harness wire.

STEP 12. Check harness between A-33X (terminal No. 2) engine control relay connector and C-307 (terminal No. 1) ETACS-ECU connector.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 13 .
Repair the damaged harness wire.

STEP 13. Check harness between C-314 (terminal No. 1) ETACS-ECU connector and D-22 (terminal No. 5) fuel pump connector.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 14 .
Repair the damaged harness wire.

STEP 14. M.U.T.-III actuator test



  • Refer to Actuator Test Reference Table .

  1. Item 05: Fuel pump relay

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.