Pull the cigarette lighter out and make sure that a piece of foil from a gum wrapper hasn't gotten into the socket where the lighter goes.
Had this happen in my 75 Vet years ago.
Drove me nuts until I figured it out.
Also pull the lighter out and leave it out to make sure it isn't stuck.
96 T/A, Black/Graphite Leather, T-Tops, 6 speed, 10 speaker Delco/Bose "Monsoon"
Original owner, 201k miles and counting.
Total engine rebuild at 187,020 miles. AIR delete, bored .030 over.
Comp cams Xtreme Energy LT1 266HR-14 street cam and springs.
Custom leather interior at 190k miles. Total repaint 193k Miles