Code No. P0627: Fuel In-tank Pump Control Circuit Malfunction


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 (terminal No. 2) 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. 47) 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.

TROUBLE JUDGMENT


Check Conditions
  • Battery positive voltage is 8 - 16 V.
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
Judgment Criterion
  • When the engine-ECU turns on the fuel pump relay, the fuel pump relay terminal voltage of the engine-ECU continues to be less than the specified value for more than 1.5 second.


  • When the engine-ECU turns off the fuel pump relay, the fuel pump relay terminal voltage of the engine-ECU continues to be more than the specified value for more than 1.5 second.

FAIL-SAFE AND BACKUP FUNCTION



  • None

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
  • Open/short circuit or harness damage in fuel pump control circuit, or loose connector contact.
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the fuel pump driving.

  • Ignition switch: ON
  • Check for pump operating noise near fuel tank
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 ).
Go to Step 2 .

STEP 2. Connector check: C-403 ETACS-ECU connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Check fuel pump relay.

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

Q. Is the check result normal?
Go to Step 4 .
Replace the ETACS-ECU.

STEP 4. Connector check: B-09 engine-ECU connector

Q. Is the check result normal?
Go to Step 5 .
Repair or replace the connector.

STEP 5. Perform voltage measurement at B-09 engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 47 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6 .

    Check intermediate connector A-17, and repair if necessary. If intermediate connector is normal, check and repair harness between B-09 (terminal No. 47) engine-ECU connector and C-403 (terminal No. 11) ETACS-ECU connector.

    • Check power supply line for open/short circuit.

STEP 6. Check harness between B-09 (terminal No. 47) engine-ECU connector and C-403 (terminal No. 11) ETACS-ECU connector.
note Before checking harness, check intermediate connector A-17, and repair if necessary.

  • Check power supply line for short circuit and damage.

Q. Is the check result normal?
Go to Step 7 .
Repair the damage harness wire.

STEP 7. Check the fuel pump driving.

  • Ignition switch: ON
  • Check for pump operating noise near fuel tank
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.