I used to have a fiat X19 Bertone which gave me constant electrical grief,including the headlights opening and closing at random and a dodgy starter motor.
When I contacted the owners club to try and get a plausible wiring diagram, they pissed themselves laughing and suggested that I start all over again as the diagrams they have only actually apply to the cars it was taken from, as they tended to be wired with whatever was lying around the Bertone bit of Fiat's factory.
Mind you, at least it didn't have electrics by Joe "Prince of Darkness" Lucas.
I always used to smack the solenoid with a shifting spanner before turning the key.:)