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

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.

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.

Judgement 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.

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.

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

OK: Operating sound of fuel pump can be heard

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

	Go to Step 2.

	Go to Step 3.

	Replace the ETACS-ECU.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Ignition switch: ON

(3)Check the voltage between the engine-ECU connector (FP/R terminal) and body earth.
OK: System voltage

	Go to Step 4.

	Repair FP/R line between ETACS-ECU connector and engine-ECU connector.

	Go to Step 5.

	Repair the connector(s) or wiring harness.

OK: Operating sound of fuel pump can be heard

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

	Replace the engine-ECU.