to answer your question,the cluster will probably have to be replaced.I have been replacing alot of these in the past weeks.I suggested cleaning the ground first because if there is a bulletin on something gm wants us to follow that first,and if it doesn't work then start diagnosing it.as far as anything else,that is all you can do.as far as replacing it you can replace it yourself but it will have to go to the dealer to be re-programmed.no other way around it.it's your choice if you replace it or the dealer does.replacing the cluster should fix the problem.good luck