Does anyone know what the two terminals on the bottom of the fuse block are for? I was wondering if you can connect a battery companion to these terminals? They are marked with a + and - symbol.
Those are the accessory terminals. Nothing goes there from the factory- they are just extra to allow you to install something later. They are live only with the key on, so no, you can't use them for a battery tender.
If I'm not msitaken they are live all the time at least on my 2006 S50 they are. I have my batt charge leads hooked up to them and charge my batt all the time with the key off. They are fused.