Underseat plug not used. Glow plug relay?

Hi guys

Just been messing under the drivers seat of my td5 defender around by the ECU in anticipation for fitting an aux fusebox.

Anyway, I've come across a relay connector that isn't plugged into anything. And after researching its connector C0215, which is meant to be glow plug relay. Should there be a relay on this plug?

If not, can I use the thick brown wire as the positive to my fuse box?

Thanks guys

Any ideas folks or is it a daft question