if you mean automaticly switched, it would prolly be better to use power thru the ign switch so it's disabled when the keys off - never know when the fancy electrical stuff might decide to burn yer house down, but whichever, I wouldn't use the coil as the supply line

Bill

Moved over to the Passing Lane

"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