Under the rear seat yeah.

I fyou un tape the wiring behind the carpet, (prob be easier to take seat out), you will find a thick black and red wire, this is feul pump supply, a thick brown wire, this is the earth fo pump and screws to self tapper, right near where seat bracket is, there is at least one other I think it is brown with a red trace, very thin, that will be the gauge feed mate, as I say cut the tape off quite a way back, as the looom around the plug for the fuel computer under the seat is wrapped up weird and may confuse the issue

Personally Im sure it will be the tank / sender