Range function on FC, no voltage on wire

[MarkV6]

Fitting a genuine MK3 digi dash to my '97 Calibra, wired up as per the howto on VXON.

Everything works except the range function on the FC?? Getting 0v on the blue/black wire.

Found the wires underneath the car for the fuel sender blue/black and a brown, getting a 12v on those. The resistance also changes on the sender pins when the float moves.

Looked to TIS and it said low resistance when tank empty and high when full, so if I run a new wire from the sender to the FC which side of the sender do I go from??? The blue/black or the brown??

If I wire the blue/black wouldn't the voltage go straight to earth through the FC and dash?? Thus using the brown wire I'd force the voltage through the sender?

Also does anyone have a proper Calibra/Cavalier wiring diagram?? I have part of the FC wiring diagram which shows the blue/black from the tank going to the FC and dash?