You sound like you have more than one problem but here are all the likely culprits:

All your fuses need to be pulled, the clips cleaned and re-tensioned and any plastic body and/or "tin" metal fuses replaced with ceramic and copper. You should do this anyway.

Halfmoon plug has become mostly unseated on the back of the IP.

The ground(s) for the IP is not connected but that would likely cause other issues (maybe not on an 1989, though?).

Alternator ground wire is faulty or the red exciter wire is broken...99% chance. This IS almost a guarantee the issue with all you warning lights and lack of charging.

If you pull the IP to re-seat the halfmoon plug, under no circumstances hook up the red/white wire unless you have a tachometer...you will want to because it looks like it fits right there. Doing so will destroy the speedo.