i was driving on the highway today and my service engine light came on with the security light, but at that time i noticed something weird, my speedometer stopped working and my tach was bouncing around from 0 to 2500 and higher when the engine speed was about 2100 at the time. but a second or 2 later everything works fine? this keeps happening but im afraid its just not going to work at some point...what could be causing this? bad sensor? fuse? the lighter power source is also affected(turns off my navigation) and my radio goes dead for a moment. the only weird thing is all the other gauges still work fine??? help please

 

anyone know? the car runs fine just the tach and speedo die for a second or 2 and they bounce around and then its fine? at that time though the air bag light the security light and the ses light all come on briefly (very quick) and then everything is normal