I'd say yes Paul - if you're using a relay, then the column horn button gives a ground to the relay, letting it pass the power to the horn [+], then the horn would need a ground for the power to flow
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
