Fuel Pump Circuit Check

Fuel Pump Circuit Check










Troubleshooting

1. Check fuel pump control system for operation.





Is fuel pump heard to operate for 3 sec. after ignition switch ON?
YES
Fuel pump circuit is in good condition.
NO
Go to Step 2.

2. Check fuel pump relay power supply.

Disconnect fuel pump relay from relay / fuse box with ignition switch turned OFF.
Check proper connection to fuel pump relay at each terminals.
If it is OK, turn ON ignition switch, measure voltage between engine ground and each "BLK/RED" wire terminals.

Is voltage 10 - 14 V?
YES
Go to Step 3.
NO
Go to Component Tests and General Diagnostics ECM Power and Ground Circuit Check.
If result in good condition, "BLK/RED" wire open or shorted to ground circuit.

3. Check fuel pump relay.

Check fuel pump relay, referring to Testing and Inspection Fuel Pump Relay Inspection.

Is relay in good condition?
YES
Go to Step 4.
NO
Faulty relay.

4. Check fuel pump relay drive signal.

Disconnect connectors between floor harness and instrument harness with ignition switch turn OFF.
Connect fuel pump relay to relay / fuse box.
Check proper connection to "GRY/BLU" wire terminal at engine harness coupler and "BRN/YEL" wire terminal at instrument harness coupler.
If they are OK, connect voltmeter between "G04-12" terminal and vehicle body ground.
Measure voltage at after 3 second ignition switch turned ON.

Is voltage 10 - 14 V?
YES
Go to Step 5.
NO
"BRN/YEL" or "GRY/BLU" wire open circuit or shorted to ground circuit.

5. Check fuel pump relay drive signal.

Measure voltage at within 3 second after ignition switch turned ON.

Is voltage 0 - 1 V?
YES
Go to Step 6.
NO
Substitute a known-good ECM and recheck.

6. Check wire circuit.

Turn OFF ignition switch.
Connect connectors between floor harness and instrument harness.
Detach fuel tank, referring to Fuel Tank Removal and Installation Fuel Tank Removal and Installation.
Disconnect connector from fuel pump.
Measure resistance between "PNK" wire terminal and vehicle body ground.

Is resistance infinity?
YES
Go to Step 7.
NO
"PNK" wire shorted to ground.

7. Check fuel pump circuit.

Turn OFF ignition switch.
Connect service wire between "G04-12" terminal and vehicle body ground.
Turn ON ignition switch, measure voltage between "PNK" terminal at fuel pump connector and vehicle body ground.

Is voltage 10 - 14 V?
YES
Go to Step 8.
NO
"PNK" wire open circuit.

8. Check fuel pump circuit.

Turn OFF ignition switch.
Check that there is continuity between "BLK" terminal at fuel pump connector and vehicle body ground.

Is there continuity?
YES
Faulty fuel pump.
NO
"BLK" wire open circuit.