Can anyone tell me where the large black wire that is connected to the top of the battery ( not the negative terminal ) actually leads to.

I think that I may have a short and I need to know where that wire leads.
If anyone has a chiltons or any other repair manual and can look it up. Please let me know what it goes to.

Thank you very much for whatever help you can offer.
Adam

BTW this is for a 2003 New Beetle 2.0