wiring help

[55consul]

Hi,have just finished installing a 4.6 ford modular v8 from a 99 mustang in my 55 consul,now sorting out the wiring .The wiring loom was cut at the bulkhead so i only have the engine bay wiring which a am unpicking.my question is there are two wires to each coil on plug one thick white/green same colour to each cop and one thinner different colour,this i assume to be the trigger wire from the ecu.So is the thick common one live when ignition on or to ground and the trigger powering the coil .Cheers