Help on Tac

I got a 92 civic CX HB. Is the lowest model and has no tac and iss a manual. I bought one and got it all wired up except for i cant find where the tac wire goes. My wireing diagram says i got an optional tac wire comming off my distributor and i tryed that wire but it did'nt work. Any Ideas of whut wire it goes to? thanx