A 1990 chevy z-71 have head lights no park lamps front or back no tag light no dash lights
This could be a bad switch,meaning blinker/headlight assembly on your column.
I do believe the light switch is on the dash, this is a possibility, not sure on if there is a relay or not, just check. Another thing you could do is if you have a test light to check for power, start tracing wires from the headlamp switch.
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