Land Rover Repair: Disco 200 TDI Fuel guage fault, wiring books, return signal

Question
Hi,

We have just purchased a J reg. 200 TDI and it constantly reads totally empty regarding fuel.  The needle reads below zero and the warning light is constantly on.  We have filled the car,so we know it is not empty.

On removing the inspection cover to the fuel pump/sender unit, we have found the assembly to have a loose wire coming from the main loom to the connector before the sender unit.  We have earthed this to the floor of the car, but still no joy.  

Is there anyway to tell if the sender unit is dead before we shell out £100 on a new one?  Have we missed something? The sender unit does not look like the one in the manual, so we are unsure if it is the correct one for the car.  It has a flat white connector on the top of the unit and is metalic/rusty in colour.

I hope you can help as we are at a complete loss.

Thanks again
Helen  

Answer
Helen, I am in the USA and I don't have wiring books for the UK cars.  In out cars we have three wires to the sender, reference power, return signal, and earth.

Jumping return to reference would yield full, earth would yield empty.

Yours is probably similar.

Hope this helps