My check engine light comes on and my speedometer and odometer stop working until I hit a bump and then they start working

Hi, I can tell you that I was having a simular problem with my 2001 Chevy Silverado. The check engine light would come on and I lost both the speedometer and odometer. I also lost gas gauge, and oil pressure gauge.I would hit a bump and they would start working, but light would stay on. I bought the obd-2 meter to read codes and erase them so the light went off. This continued for 8 months. Finally, I started moving wires around under dash when gauges stopped and they would come on and off? Took me right to the circuit board on the ignition switch. I mean I tried everything possable to solve this and told a G.M. mechanic. He said I was right that it would be the switch and that most of you're wires that go to gauges and speedometer come from the ignition switch. I changed it and it has been fine since. You might try what I did see if you can do this while driving, i don't no, but if so be carful on the road. You may need to take it in also.There is something loose a ground wire or hot doing this. I would bet it is in the ignition switch. Best of luck,
Shastalaker7