Hello I will be helping you with your silverado.Do you have a test light? On the drivers side of the dash is a fuse block test to see if you have power on the trans fuse. The fuse is probably good (not open or blown) The ignition switch under the lock cylinder is not providing power to the fuses. Its the electrical part that uses contact inside the switch and the contacts are bad. Let me know what you find, and if you need more help I will be on later tonite
My truck does not have a trans fuse in dash fuse box. Clean contacts in switch still the tach and speedometer still will not work. This truck had this problem about 4 months ago and we unplugged the sarter relay and plugged it back in and it fixed the problem. This time we changed that relay and it still will not work.