If irrc (it's been a while since mine has worked for a long enough period of time for me to relearn how it opperates) it's from the clutch with a bunch of other conditions (neutral, stationary etc).

 

Mine hasn't worked for a while either but on the TCT, you can put the handbrake on and put it in neutral so you can take your foot off the brake without it restarting.

 

On my manual (MY2011) the S/S doesn't cut in (provided the battery and all other conditions are right) until the clutch is released in neutral. If you sit at the lights in gear with the clutch depressed the S/S doesn't cut in.

 

That’s what the gear position sensor is for on a manual Giulietta?

 

Merely answering the OPs question. Not sure if it works as soon as the gear position moves to neutral. Certainly the engine restarts as soon as the clutch is depressed so presumably there is a clutch position sensor as well

 

On a manual gear should be in neutral, vehicle speed should be zero, clutch pedal not pressed - this should stop the engine
As soon as you press the clutch pedal in, the engine should start

 

So, manual = clutch pedal.
Thanks all.