Oil Light Problem

[DAVID C]

On my wife's '86 GN, the oil/choke light comes on even with 40 psi of pressure. I've replaced the switch... Still on 80% of the time. I've also noticed the interior lights are flickering when the engine's running. I haven't had any time to check much. Anyone else run into this? I added several grounds years ago. But nothing to the dash. Any chance the alternator could cause this? Any suggestions are greatly appreciated. Dave C.