What do I need to look for to solve the blinking dash light sensors and gauges?

What is your question?

When I am driving on a smooth road and go around a curve or go down into a dip in the road or hit a bump, all of the dash light sensors start blinking and the fuel gauge pegs to empty and the speedometer pegs also. Its only a quick flash like something is losing the ground or something. I took it to Auto Zone and had the engine light checked. All of the codes that came up said basically that it lost its ground some where. I checked and replaced the ground cable on the battery because it was loose but that didn't help solve my problem.Any idea where the problem could be??