Fuel Pump Electronic Control Unit (ECU) - (SC300 & SC400)
Fuel pump operating speed is controlled by operating condition of the engine such as: starting, idling, light load or heavy load. Engine Control Module (ECM) delivers an input signal from FPC terminal on ECM to FPC terminal on fuel pump ECU in accordance with engine operating condition. Fuel pump ECU uses this input signal to determine how much voltage should be delivered to fuel pump for varying fuel pump operating speed. When engine starts, ECM delivers about 5.0-volt input signal to fuel pump ECU. Fuel pump ECU then provides battery voltage to fuel pump so fuel pump operates at high speed. After engine starts, during idling or light loads, ECM delivers about 2.5-volt input signal to fuel pump ECU. Fuel pump ECU then provides about 9 volts to fuel pump so fuel pump operates at low speed. If engine is under heavy load, ECM delivers input signal to fuel pump ECU and fuel pump ECU then operates fuel pump at high speed. Fuel pump ECU is located behind inner trim panel on driver's side of vehicle, behind driver's side door pillar. See Fig 1.