Congrats on finding the bad ground connection. Since it has happened to you twice now make sure you clean the chassis metal under the bolt and make sure there is a star and lock washer involved in the final repair so there is no chance of a third event. By the way I went looking for what seems to be the likely lighting front ground point cable on my 2013 ACE 30.1 and it is bolted to driver's side chassis support on the right side of the radiator.
__________________
|