In older vehicles this is done via an Ignition Distributor, with newer vehicles using Multi-Outlet Coils with Ignition Leads connected directly to the Spark Plugs. HT Leads, ignition cable, plug leads, ignition wires.
HT Leads Ignition Cable Kit HOES831 Lemark 12121247511 12121247514 12121247523
HT Leads Ignition Cable Kit 73122 Intermotor 030905430E 030905430F 030905430G
HT Leads Ignition Cable Kit 73827 Intermotor
HT Leads Ignition Cable Kit 73523 Intermotor 46413088 71776576
HT Leads Ignition Cable Kit HOES191 Lemark
HT Leads Ignition Cable Kit 76189 Intermotor 32722-PJ5-600
