Fuel Pump Driver Module
The Fuel Pump Driver Module (FPDM) is powered by a connection from the fuel pump relay in Rear Junction Box (RJB). The fuel pump relay is energized on opening the driver's door or when engine crank (power mode 9) is initiated using the stop/start switch. The FPDM supplies power to the Low Pressure (LP) fuel pump, and adjusts the power to control the speed of the LP fuel pump and thus the pressure and flow in the delivery line.
A Pulse Width Modulation (PWM) signal from the Powertrain Control Module (PCM) tells the FPDM the required speed for the LP fuel pump. The on time of the PWM signal represents half the LP fuel pump speed, for example, if the PWM signal with an on time of 50%, the FPDM drives the LP fuel pump at 100%.
The FPDM will only energize the LP fuel pump if it receives a valid PWM signal, with an on time of between 4% and 50%. To switch the LP fuel pump off, the PCM transmits a PWM signal with an on time of 75%.
The output pressure from the LP fuel pump will change with changes of engine demand and fuel temperature. The PCM monitors the input from the LP fuel sensor. The PCM then adjusts the speed of the LP fuel pump as necessary to maintain a PCM requested output pressure of 5.5 bar to 7.3 bar (79.9 to 105.9 Ibf/in.2 ) absolute, during engine start up and engine shut down. Target pressure for the LP fuel delivery line is raised to 7.3 bar (79.9 Ibf/in.2 ) gauge.
If the Restraints Control Module (RCM) outputs a crash signal to the PCM, the PCM will de-energize the LP fuel pump relay to prevent any further fuel being pumped to the engine.
If the PCM does not detect pressure in the fuel delivery line, it stops, or refuses to start the engine and stores the appropriate Diagnostic Trouble Code (DTC).
The PCM receives a monitoring signal from the FPDM. Any DTCs produced by the FPDM are stored by the PCM.
DTCs can be retrieved from the PCM using an approved diagnostic system. The FPDM itself cannot be interrogated by the approved diagnostic system.