Dont fire the panel up without a chassis ground. Most of it wont work without it anyway but... if the wrong circuit seeks a ground through another circuit you have problems.
A dedicated ground wire on one of the screws that attach bezel to the housing down to the steering column area is a good move. What works best for me is attaching to the screw that holds the fusebox up and a male/felame disconnect in the line. That way I can lower the column, pull the panel outward ,and still have a ground for testing.
Happy moparing
