[AdamIsAdam]

I plan to run the ground wire to the starter relay, which is grounded to the battery to see if that helps. I'll also run the main power there, rather than tapping into the wire that comes from that relay. Heck, for now I may even run both wires directly to the battery just to see if that fixes the problem before cleaning up the wiring around the battery.

But just fyi, the instructions state that the chassis is an acceptable ground (see attached). Again, just sharing of info because, well, I'm the one having issues, so I'm certainly not trying to reject any advice - far from it!