"PS I have no idea why it shows as a new member, maybe because I do not post often (too busy camping"
Yes, that is why. 27 posts. The different classes, New Member, Senior Member are based on the number of posts that you make, not the year joined. Someone will probably let us know when they change.
As for the original question, follow the problem positive cable and look for a place where it may be pinched, or worn insulation causing a dead short to ground. It may be where it goes through a metal wall and grommet is broken or missing, or along a frame rail or other metal grounded component.
Ken