1985 Chevrolet Corvette - Instrument Cluster Lighting

My instrument panel lights will not Illuminate , sometimes when will come on and goes off, when starting.

While your post is not completely clear, I’d suggest checking the instrument panel dimmer for proper functioning.

The dash in your car is one large electronic module. It is 34 years old and likely has a failure of several components. It might be a fault in the control that varies the brightness of your interior lights if those also have a problem. If that control is OK, then you are in for some serious internet searching to find a company that can repair this part.