Fuel Tank and Lines: Operation

WARNING: This page is about a different car, the 2018 Land Rover Discovery and 2017 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.

The fuel pump is supplied power via a fuel pump relay which is located in the Rear Junction Box (RJB). The fuel pump relay is controlled by the Body Control Module/Gateway Module (BCM/GWM) assembly. The fuel pump relay is active in all power modes, except in power mode 0 (ignition off). The Powertrain Control Module (PCM) is connected to the BCM/GWM assembly to receive a 'wake-up' message. In the event of an accident the Restraints Control Module (RCM) outputs a crash signal to the BCM/GWM assembly to disable the fuel pump relay.

Fuel Level Sensors

Two fuel level sensors are used to measure the amount of fuel remaining in the left and right sides of the fuel tank. Both sensors are connected to the Body Control Module/Gateway Module (BCM/GWM) assembly hardwired via the external electrical connector. The external electrical connector is located on the fuel pump module top flange assembly. The sensors output signals processed by the BCM/GWM assembly and passed to the Instrument Cluster (IC) to display the remaining fuel level and low fuel warning.

The fuel level sensor signals are converted into High Speed (HS) Controller Area Network (CAN) comfort system bus messages by the BCM/GWM assembly. The messages are used by the IC to display the remaining fuel level and low fuel warning. The fuel level signals are also monitored by the Powertrain Control Module (PCM) to store Diagnostic Trouble Codes (DTCs). The PCM uses the measured value for misfire detection when the fuel level is below a predetermined capacity.

Low Fuel Strategy

CAUTION: When 2.0 liters of useable fuel remain, the engine can be restarted and will run for 60 second intervals, until this fuel is consumed. Continuous attempts to re-start the vehicle after the useable fuel has been consumed will cause possible damage to the High Pressure (HP) fuel pump.

The Powertrain Control Module (PCM) is programmed with a strategy which shuts the engine off before the fuel tank runs dry. This is to prevent fuel system damage by air being drawn into the HP fuel pump.

A warning message is displayed on the Instrument Cluster (IC), when the fuel level becomes low. It means that the fuel in the tank reaches approximately 4.0 liters of useable and 0.5 liters of un-useable fuel remain.

When a further 1.20 liters of fuel is consumed a misfire condition is induced, to again alert the driver to this condition. The misfire will continue until a further 0.8 liters of fuel has been consumed.

The engine will shut down when only 2.0 liters of useable and 0.5 liters of un-useable fuel remain in the tank.

To reset the fuel strategy after engine shut off:

Park with the vehicle on a flat level surface.
Add a minimum of 5.0 liters of fuel to the fuel tank.