BMW Airhead motorcycle ignition The sketch is copied from a full wiring diagram. Although not drawn as such in the diagram, the trigger wire (to pin 6 of the unit) is the center connector. The ignition control unit pin 6 has a brown wire; pin 3 has a blue wire, pin 5 has a green-yellow wire; pin 4 has a green-glue wire, pin 1 has a black wire, pin 2 has a heavier brown wire. 5.9 firing order — Ricks Free Auto Repair Advice Ricks Dec 05, 2012If you’re tracking down a wiring issue, Eautorepair is the better choice. Eautorepair redraws factory wiring diagrams in color and includes the component, splice and ground locations right in their diagrams. That saves a lot of time because you don’t have to refer back to the component locator or circuit locations.