Dash lights
Check gage cluster frame to dash board frame ground, it grounds where it screws into the sheetmetal dash frame. check lightbulbs. These are first 2 places i'd check. Wire going into printed circuit card for backlighting is orange. Unplug it, check for power at orange wire going into instrument cluster when headlight switch is on. Some people run a seperate additional dedicated ground wire, or ground strap from the cluster to the dash frame just to help prevent grounding issues