Instrument cluster
 

I am working on a 1989 928S, a few days ago my instrument cluster just stopped reading correctly and my tach and speedo stopped working. My digital milage no longer works. The other gauges function but do not read correctly. Fuel, oil pressure, temperature, voltage is the only thing reading correctly. Just looking to see if anyone else has had this issue.

Check all your connections on the back of the instrument pod and check the fuses. There are 3. Fuses 5, 10, and 24 must all be functional

Sounds like a possible issue with the instrument cluster ground or a failing power supply to the cluster. Check ground G5 behind the dash and inspect the cluster connector for corrosion or loose pins. Also worth checking fuses and the ignition switch, as a failing switch can cause weird gauge behavior.