[davepl]

IIRC, the purple is the heavy gauge wire that will ultimately be called upon to fire the solenoid and engage the starter.

That wire has to be darned near perfect. Corrosion, a bad splice, marginal neutral safety switch, or pretty much anything that's not near superconducting can cause the solenoid not to engage, causing a no-start. There's no click or anything, just dead. Usually doesn't happen until the engine and starter are hot though.

The idiot lights are usually switched ground, so cutting wires would just prevent them from lighting, not vice versa.

The long and short of it is that the NSS has two circuits - one for the backup lights and one for neutral/park. Green is the lights. Purple is the starter.