80 GTV seizures

[kartone]

There might be a thread on this already. My 1980 GTV has started to suffer from sudden engine stoppages due to loss of electrical power: the engine dies whether hot or cold, at 50 kmh or 100 kmh, all announced by the battery light coming on.
The engine will restart immediately when cranked but sometimes dies just as quickly with the battery light coming on.
What is a quickest way to test the ignition switch (I wiggled the switch with the ignition key while the engine was on to no avail)?
Is there a main relay to test? 
Italian electrons, they must be missing the conductivity of the Milanese fog ! 

[giulia_veloce]

Common problem

Usually the ignition switch.

Just change it.

Robert

[kartone]

Will do Giulia.
Does anyone have an ignition switch they are willing to part with ?