Hi, i fitted a new aftermarket steering wheel and connected all the wires up on the boss ok with the correct ring and everything but horn is not working. I had swapped the loom round into my cab (s2 loom) and ive put one plug back on the horn that i labelled horn but i have a spare wire with a spade on the end of it that is black with white stripe and its next to the horn.Is this an earth for the horn,if not where does it go?