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


OPERATION



  • The fuel pump drive power is supplied from engine control relay connector terminal to fuel pump relay (ETACS-ECU connector terminal F/PB) in the ETACS-ECU.
  • The battery voltage is applied by the ignition switch connector terminal or OSS-ECU connector terminal to the fuel pump relay coil (ETACS-ECU connector terminal IG1) in the ETACS-ECU. The engine-ECU connector terminal FP/R 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 ETACS-ECU connector terminal FP/R).
  • When the fuel pump relay is turned ON, the battery voltage will be supplied from the fuel pump relay (ETACS-ECU connector terminal F/P) 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. Check fuel pump relay.

  • ETACS-ECU connector check.
  • Perform continuity test in fuel pump relay (Refer to ).

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

STEP 3. Perform voltage measurement at engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal FP/R and body earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 4.

    Repair or replace the connector, or check and repair harness between engine-ECU connector terminal FP/R and ETACS-ECU connector terminal F/PR.

    • Check power supply line for open/short circuit.

STEP 4. Check harness between engine-ECU connector terminal FP/R and ETACS-ECU connector terminal FP/R.

  • Check power supply line for short circuit and damage.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or repair the damage harness wire.

STEP 5. 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.