Circuit/System Testing
- Ignition OFF, disconnect the affected fuel pump relay.
- Test for less than 5 ohms of resistance between the ground circuit and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
- Command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the engine control module (ECM).
- If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the fuel pump relay.