Inspection Procedure 21: Fuel Pump System


OPERATION



  • The fuel pump drive power is supplied from engine control relay (terminal No. 2) to fuel pump relay (C-406 ETACS-ECU connector terminal No. 1) in the ETACS-ECU.
  • The battery voltage is applied by the ignition switch <Vehicles without KOS> or the OSS-ECU <Vehicles with KOS> to the fuel pump relay coil (C-417 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 (terminal No. 96) so as to conduct power to the fuel pump relay coil (via the C-403 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-414 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 fuel pump drive circuit, or loose connector contact.
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-403, C-406, C-414 and C-417 ETACS-ECU connectors

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 ETACS-ECU.

STEP 3. Connector check: B-27 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-27 engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 96 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 5.

    Check and repair harness between B-27 (terminal No. 96) engine-ECU connector and C-403 (terminal No. 11) ETACS-ECU connector.

    • Check power supply line for open/short circuit.

STEP 5. Perform voltage measurement at C-406 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-37X engine control relay connector

Q. Is the check result normal?

    Check and repair harness between A-37X (terminal No. 2) engine control relay connector and C-406 (terminal No. 1) ETACS-ECU connector.

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

STEP 7. Connector check: D-24 fuel pump connector

Q. Is the check result normal?
Go to Step 8.
Repair or replace the connector.

STEP 8. Check fuel pump operations.

  • Fuel tank pump operation check (Refer to ).

Q. Is the check result normal?
Go to Step 9.
Replace the fuel tank pump and gauge assembly.

STEP 9. Perform resistance measurement at D-24 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-24 (terminal No. 4) fuel pump connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 10. Perform voltage measurement at D-24 fuel pump connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 5 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 12.
Go to Step 11.

STEP 11. Check harness between C-414 (terminal No. 1) ETACS-ECU connector and D-24 (terminal No. 5) fuel pump connector.

  • Check power supply line for open/short circuit.

Q. Is the check result normal?

    Check and repair harness between B-27 (terminal No. 96) engine-ECU connector and C-403 (terminal No. 11) ETACS-ECU connector.

    • Check power supply line for damage.
Repair the damaged harness wire.

STEP 12. Check harness between A-37X (terminal No. 2) engine control relay connector and C-406 (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-414 (terminal No. 1) ETACS-ECU connector and D-24 (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

  • Item 9: Fuel pump
OK: Operating sound of fuel pump can be heard.

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.