digital gauges stuck in same setting need help

[Niterider73]

Hello I have a 84 300zx turbo and my battery registers 8v all the time now and my temp gauge is always registering normal temp and these are registering at the same setting when i first start my car up in the morning, but my oil pressure still works good. These just started doing this about 2 or three days ago, and I have a brand new battery in my car. What could be the problem here???