Hi
I have installed a sub and amp into my car but they don't work! :confused:
I believe its because my headset is a little bit weird. I has a "subwoofer setting" which I am guessing turns the subwoofer on and also has a subwoofer RCA output cable along with the usual red and white RCA's
I have wired up the amp and sub asyou usually would but I think the subwoofer setting and RCA need to be connected somehow
Does anyone have any ideas how these would be wired in?

Check your cables... the positive wire to the battery and your negative to the body of the car but make sure there is no paint on the surface when screwed in for the negative wire

Yes, just a little cheapo multi-meter is a great tool to check all your power and grounds.
Make sure at least 10AWG wire on both, and please fuse it right off the battery termanal
The turn on wire is of course for turning on the amp, not the sub. Again, ck your voltages!