There are generally 2 main terminal connectors on a instruments for lights, etc. One of them may be coming loose. You will have to remove the instruments to see. I reccomend taking it to a body repair shop if you are not comfortable as you have to remove all the has trim pieces by pulling on them gently and removing trim screwws that are often hidden by caps. Then you have to pull on the instruments gently and reach behind it to remove anything keeping it from coming out or that may be enough to feel if the connector is loose.
You may have a bad set of instruments that need replacing. It is hard to say until it is removed.