kamtra

My 90 LS400, now that i'm trying to sell it, just did something weird. I had a fuse blow while driving that took out my windows, sunroof and dash lights. I replaced the fuses and checked all the others. Everything works fine now except that the backlights for my nakamichi radio AND AC unit only work properly when the ignition is on...when I start the engine and the headlights are on, all the back lights turn off. I thought maybe all the backlights had blown out until i realized that they still work (dim when headlights are on too) until i start the engine- then it all goes black except for the AC control button lights. This only effects the back lights. Also when the engine is running and headlights are OFF the radio backlight works fine..this only happens when the headlights are turned on and the engine is running. Any fuses I don't know about? A voltage regulator of some kind? Thanks!