Inspection Procedure 20: 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.