I have a 97 LeSabre with the ub3 cluster. The fuel reads full all the time, the tach is eratic, the speedometer works when it wants to. I can tap the top of the dash and the tach goes crazy. The cruse works perfect when the speedometer isn't working. Any ideas before I change the cluster?

 

It's certainly a "cold welding" (not sure if i spell it right in french we call this Soudure froide). If you can try to remake all welding on the cluster. I'm sure it will correct the problem.

I also get a similar trouble on my astro, it was a broken bulb that make a ground contact (hard too beleive but this was really the cause !)

 

Youll have to remove the cluster and check and clean all the connectors first.