Fuel Pump Control System

Fig. 52 Fuel Pump Control System:

CIRCUIT OPERATION
The ECU controls both the ON/OFF signal to the fuel pump relay ground circuit and the amount of voltage supplied to the fuel pump through the ground circuit.
The fuel pump operates via the relay under all circumstances (starting, cold and hot operation) EXCEPT normal engine operating conditions. During normal engine operating conditions the ECU varies the amount of voltage supplied to the ground circuit of the fuel pump, varying fuel pump output.

Single Pole Normally Open Relay:

FUEL PUMP RELAY
The fuel pump relay, located in the relay box in the engine compartment, allows battery voltage to be applied to the fuel pump. The ECU supplies the ground circuit to the relay allowing the windings to close the switch internally. Battery voltage is then applied to the fuel pump.

Fig. 44 Fuel Pump Operation:

Refer to Fig. #44 for fuel pump operation.