No tack indication batteries charge only on higher RPM from time to time stops running/ 97 pick up diesel 6.5 I have removed and cleaned the frame and engine, batterie grounds no change. From time to time the tack and batterie indicator come alive all random this has been going on for months
You can check for body grounds; however, there have been problems with these inst panels. It isn't uncommon for them to go bad. Also, you could try disconnecting the battery for a couple minutes and see if that resets anything for you.