It is a common problem. The wires tend to get crushed if the rear seats are used a lot and the wires haven't been correctly routed/protected which can cut through the wires or cause the loom to break up inside the sheath.
V8 Disco 1's suffer from a similar fault aswell. They tend to break the main live feed wire where it goes through the sealed hole in the top of the sender. The break is usually inside and not visible by eye. When I come across this as a fault I tend to remove the sender, drill a new hole, grommet and sealer it and then re-fit the sender to get people going.