I am in the process of working through all of my accessory wiring, and that currently includes wiring my second battery. I have an extra heavy gauge black wire with the end wrapped in blue electricians tape near the negative side of my primary battery. This looks like some sort of prep wiring for a winch or second battery and reads fractions of an ohm of resistance measured to the negative terminal of the primary battery. Anybody know if this is a second ground or just a split of the negative cable on the primary battery - i.e. can I use it as a ground for my second battery? The wire disappears into a wiring harness that I am not quite motivated enough to cut apart, so I figured I would check with the braintrust here before I dig further.