Fuel Pump Driver Module (FPDM)
The FPDM is located in the LH rear corner of the luggage compartment, behind the trim panel and is secured to the LH chassis longitudinal with 2 screws.
The FPDM receives a battery supply via the fuel pump relay in the CJB. The relay is energized by the CJB when a request is received from the ECM. Two wires connect the FPDM to the fuel pump motor and a ground is via a body ground point. The ECM is connected to the FPDM on a single wire and this is used to control the pump pressure output and consequently the pump output pressure. The ECM uses signals from the MAP sensor, the fuel rail pressure/temperature sensor and the MAF/IAT sensor to determine and control the pump output.
The ECM outputs a PWM signal to the FPDM. The frequency of the signal determines the duty cycle of the FPDM which subsequently controls the pump pressure output. The frequency of the PWM signal represents half of the 'on' time of the pump. If the ECM outputs a PWM signal of 50% on time, the FPDM will operate the pump at 100% (permanently on). If the ECM outputs a PWM signal of 5%, the FPDM will operate the pump at 10% on time. The FPDM will only operate the fuel pump if it receives a PWM signal from the ECM of between 4% and 50%. If the ECM requires the pump to be stopped, the ECM transmits a PWM signal at a cycle of 75%.
If the power supply to the FPDM from the CJB or the fuel pump relay is disrupted for any reason, the fuel pump will not operate. The FPDM is monitored by the ECM for faults. Faults with the FPDM are stored in the ECM as fault codes which can be retrieved using a Land Rover approved diagnostic system.