No idea, ask Big Blue. It still sounds like a fuse or a connector that has come apart. What was the last thing you changed, modified, repaired, messed with, etc???
Perhaps that will give you an area in which to look.
I have an 87 that I drive thru mud and water and have yet to replace a light bulb.
Bob Shaw

87 Raizer, 4.3V6, Mod TH700R4,231CHD, detroit rear and LSD front, bouncy seats, 2" lift and 32x15 BFG MT tires.