Sensor | Input signal to ECM | ECM Function | Actuator
Crankshaft position sensor (POS) Camshaft position sensor (PHASE) | Engine speed* | Fuel pump control | Fuel pump relay ↓ Fuel pump
Battery | Battery voltage*
*: ECM determines the start signal status by the signals of engine speed and battery voltage.

The ECM activates the fuel pump for several seconds after the ignition switch is turned ON to improve engine start ability. If the ECM receives a engine speed signal from the camshaft position sensor (PHASE), it knows that the engine is rotating, and causes the pump to operate. If the engine speed signal is not received when the ignition switch is ON, the engine stalls. The ECM stops pump operation and prevents battery discharging, thereby improving safety. The ECM does not directly drive the fuel pump. It controls the ON/OFF fuel pump relay, which in turn controls the fuel pump.

Condition | Fuel pump operation
Ignition switch is turned to ON. | Operates for 1 second.
Engine running and cranking | Operates.
When engine is stopped | Stops in 1.5 seconds.
Except as shown above | Stops.