Fuel Pump Electrical Circuit Diagnosis (Except Park Avenue): Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
When ignition switch is turned to RUN position, the Powertrain Control Module (PCM) enables the fuel pump relay which powers the fuel pump on. The pump remains ON as long as the engine is cranking or running and the PCM receives ignition reference pulses. If there are no ignition reference pulses, the PCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the RUN position or if the engine stops.