Fuel Pump Relay & Fuel Pump Resistor (Sequoia & Tundra 4.7L V8)
Fuel pump operating speed is controlled by operating condition of the engine such as: starting, idling, light load or heavy load. When engine is cranking and start signal is received at Engine Control Module (ECM), the ECM energizes circuit opening relay and voltage is applied to both sides of fuel pump relay. Fuel pump relay contacts are closed on one side and voltage is applied directly to fuel pump in which fuel pump operates at high speed. After engine starts during idling or light loads, fuel pump relay is energized by FPR terminal of ECM and contacts in fuel pump relay close to other side of relay. Voltage is then supplied to fuel pump by going from fuel pump relay through fuel pump resistor. Fuel pump now operates at low speed. Fuel pump relay is located in fuse/relay box at driver's side front corner of engine compartment. Fuel pump resistor is located at driver's side front corner of engine compartment, near end of fuse/relay box. See Fig 1.