Did you check the fuses with a test light? Your dash lights and taillamps go thru the HL/dimmer switches. You could even have a bad dimmer module too. Give more info and I'll help.
Phil
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86 GT TTops, 3.4 Auto.....bought from Doug of Fiero Warehouse
GM auto tech for 27 years. Specializing in electrical and computer problems. I will never be able to return as an auto tech again. I get EXTREME satisfaction helping others and will go to Extreme levels to help you if you need help. I have LOTS of free time on my hands. This forum and the help I give, allow me to have a purposeful life. Bring on the problems......LOL.