Fuel Pump and Its Circuit Check

Fuel Pump and Its Circuit Check

Wiring Diagram

Refer to Fuel Pump Control System Circuit Diagram Fuel Pump Control System Circuit Diagram.

Troubleshooting

NOTE:

The connectors of the ECM are watertight. If tester probes are directly connected to any of the connectors when checking the ECM and its circuits, the watertight performance of the connector will be affected, possibly resulting in corrosion of connector terminals and damage to electrical circuits.

Always use the special tool when checking the circuits. Connect tester probes only to the special tool's connectors.

NOTE:

Before troubleshooting, be sure to read "Precautions for ECM Circuit Inspection: in Section 1A".

1. Fuel pump control system check for operation

Remove fuel filler cap and turn ignition switch (2) to ON position.
Confirm that fuel pump operating sound in heard from fuel filler port (1) for about 2 sec. and then it stops.
Reinstall fuel filler cap after checking.

Is it in good condition?





YES -
Fuel pump circuit is in good condition.
NO -
Go to Step 2.

2. Fuel pump relay power supply check

Turn OFF ignition switch and remove fuel pump relay from fuse box No.1. Service and Repair
Turn ignition switch to ON position, check that voltage between each fuel pump relay power supply circuit (A1 - A2) and engine ground is battery voltage.

Is it in good condition?
YES -
Go to Step 3.
NO -
Repair or replace fuel pump relay power supply circuit.

3. Fuel pump relay check

Check fuel pump relay. Testing and Inspection

Is relay in good condition?
YES -
Go to Step 4.
NO -
Replace fuel pump relay.

4. Fuel pump relay drive circuit check

Turn OFF ignition switch and disconnect connector from ECM.
Check for proper terminal connection to ECM connectors.
Check that fuel pump relay drive circuit (B1) is as follows.
- Wiring harness resistance of fuel pump relay drive circuit is less than 3 ohms.
- Insulation resistance between fuel pump relay drive circuit (B1) and vehicle body ground is infinity.
- Circuit voltage of fuel pump relay drive circuit (B1) is 0 - 1 V with ignition switch ON.

Are they in good condition?
YES -
Go to Step 5.
NO -
Repair or replace fuel pump relay drive circuit.

5. Fuel pump relay drive signal check

Turn OFF ignition switch.
Install fuel pump relay to fuse box No.1 and connect connector to ECM.
Check that voltage between fuel pump relay drive circuit (B1) and vehicle body ground is 0 - 1 V for 2 sec. after ignition switch to ON position.

Is it in good condition?
YES -
Go to Step 6.
NO -
Substitute a known-good ECM and recheck.

6. Fuel pump power supply circuit check

Turn OFF ignition switch.
Detach fuel tank. Fuel Tank Removal and Installation
Disconnect connector from fuel pump.
Check that resistance between fuel pump power supply circuit (B2) and vehicle body ground is infinity.

Is it in good condition?
YES -
Go to Step 7.
NO -
Repair or replace fuel pump power supply circuit.

7. Fuel pump power supply circuit check

Connect service wire between fuel pump relay drive circuit (B1) and vehicle body ground.
With ignition switch in ON position, check that voltage between fuel pump power supply circuit (B2) and vehicle body ground is battery voltage.

Is it in good condition?
YES -
Go to Step 8.
NO -
Repair or replace fuel pump power supply circuit.

8. Fuel pump ground circuit check

Turn OFF ignition switch.
Check that resistance between fuel pump ground circuit (B3) and vehicle body ground is less than 3 ohms.

Is it in good condition?
YES -
Replace fuel pump. Fuel Pump Assembly Removal and Installation
NO -
Repair or replace fuel pump ground circuit.