Buzzing from Cluster@ around 80mph and PPPP code from OBC???

[canyonrunner1]

My 1995 525iT has the above symptoms. Also, along with the buzzing from the cluster the OBC lights keep burning out. When I replace the bulbs I get the PPPP code on the OBC display before it goes to the normal setting....Any ideas what the issue is or if they are connected in some way????? THANKS!