I hope you don't mind me butting in, but auction sales are naturally enough, sold as seen......I wonder why it was in there in the first place?
Anyway I would suspect a faulty charging regulator with the genny - unregulated output can give all sort of current and voltage variations.
The stray wire is likely to be either an engine cut out or a low oil indicator.
I've never seen a diesel generator with a 6v starter system.
John
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local