How to Check an Ignition Coil on an Aircooled Volkswagen Click to view3:24Aug 30, 2010How to Check an Ignition Coil on an Aircooled Volkswagen Beetle. Before checking the ignition coil, ensure there is 12V going to the terminal 15 on the coil. Note: Terminal 15 is positive, terminal 1 is negative. 86%(38)Views: 73K Coil Wiring Hook-Up's - Itinerant Air-Cooled itinerant-air-cooled›Technical Forums›ElectricalJul 30, 2017When i disconnect the wires from the coil I use a Sharpie to mark the coil and bundle each set of wires in blue painters tape then mark them. You don't even have to know which is which as far as + and - go just mark one side A and the other B. I'm gonna guess that you didn't know that on an old VW the black wire is + and a brown wire is ground.