Electrical question: is this supposed to be here

[Tim555]

I am still chasing down a hot no crank issue with my 1991. The new starter didn?t fix the issue. I decided to see if there was a grounding problem. I pulled the battery and found the thick negative that I think goes to the starter area. It has a splice block on it that definitely doesn?t look like it came from the factory. For context, below my hand is the battery tray. I took it apart and reseated it better than it was before. Does this thick wire in fact go to the starter? Could this be causing my issue? It didn?t feel loose, but I definitely got it seated better than it was. I?m not holding my breath, but I?d be ecstatic if for some reason this fixed it. Other info that might help is at idle the turn signals seem a bit slow and the voltage gauge moves up and down when they are on.

Edit: the splice block was on the POSITIVE side coming off the battery and then going down to the starter area.