Fuel Pump Relay

PCM energizes HO2S heater element and fuel pump using fuel pump relay. Fuel pump relay is located in the power distribution center. For fuel pump relay location within PDC, refer to PDC cover label. Fuel pump relay coil is powered when ignition switch is in Run or Start position. Fuel pump relay is controlled by the PCM switching relay coil ground on and off.

The fuel pump circuit is completed during cranking and whenever the engine is running. If the ignition switch is turned to the RUN position, the fuel pump will operate for 1-3 seconds and then shut off. If the PCM does not receive a crank or run signal, it deactivates the fuel pump by opening the relay coil ground circuit. The 1-3 second time limit is used to prevent unnecessary operation of the fuel pump once the system is pressurized. If the engine were running, the PCM would maintain the fuel pump relay coil ground allowing continuous operation of the fuel pump.