Speedometer and cruise control

Moin, I have the following 2 problems with my Omega. I tried the “search” already, but found nothing about it yet or the matching probably overread. 1) Tacho Since last winter my tacho spins. Sometimes he doesn’t go … a cheerful back and forth during the ride. Accordingly, the on-board computer also delivers “interesting” results. It came out of the blue, no repairs were done ect. during this time … also no radio changed (has the original inside). Where to start looking ? 2) Tempomat This is already about 2 years without function. Suddenly he didn’t want any more, at the beginning he felt briefly (approx. 2days) when driving with high-light… Where should one start with the diagnostics here? The two errors occurred with approx. 1 year distance, insofar I don’t necessarily see a connection.