Circuit Description

When the ignition switch is turned ON, the Engine Control Module (ECM) energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain on as long as the engine is running or cranking and the ECM is receiving Crankshaft Position (CKP) sensor reference pulses. If no CKP sensor reference pulses are present, the ECM de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON or the engine is stopped. The ECM applies a low current signal of about 7 volts to the fuel pump relay control circuit with the key ON and the engine OFF. The ECM uses this signal to detect the integrity of the fuel pump relay control circuit.