Description And Operation: Operation

When the Powertrain Control Module (PCM) receives a 'Start' or 'Run' signal; It energizes the Fuel Pump relay which sends a continuous 12 volt supply to the Fuel Pump Control Module (FPCM). The PCM also sends a control signal directly to the FPCM which regulates the Pulse Width Modulated (PWM) signal that will be sent to the Fuel Pump Module. The PWM signal (duty cycle) will vary from 10-100% depending on the input of the Fuel Rail Pressure sensor (FRPS) and other engine demands. The PCM receives a PWM signal from the FPCM representing the state of all inputs and outputs of the FPCM. This is a Constant Pressure Fuel system which means any pressure test performed on the Fuel Pump would show a continuous pressure (regardless of the changes in PWM). If a pressure sensor fails or other failures are present; The duty cycle goes to Limp mode (100%) to maintain fuel pressure.