I have never run into such an issue with my car after 4 years of owning it. 1989 irocz tpi 305 5 speed.. I was doing a cluster LED swap and as I put everything back I notified the gauges were basically almost pegging out. I reseated the cluster again and now no gauges work whatsoever. When I turn on my headlights I hear the annoying chime and it doesn't turn off, even if I start the car. The fuse Is fine and there is current leading to it. The temperature doesn't even peg out anymore!! Most of the LED bulbs work, like 90 percent of them I think except one regardless of what position I wiggle it into. I really need to get these gauges working again, I tried 3 leftover clusters of mine and absolutely NONE of them work!!!!!

 

Austinthirdgen.org has wiring diagrams for the instrument cluster. Check them out and do some probing to find where your problem my be. I would look at the connections going to the instrument cluster as that is the most likely culprit. HTH!