steering wheel control button lights.

06 Sierra, 4X4, 5.3, 100k miles. Problem started with the dual climate (hot/cold) lights going out. Then the button lights on the stock radio. Then the lights for the steering wheel buttons. They all are out but will randomly light up with bumps in the road then go out again. Sounds like a loose wire or a bad solder somewhere to me. But where do I start my plan of attack to fix these issues? Any advise would be appreciated!!! Thanks