Omega B – Y22XE – Interior deceleration lamp defective

Hello you love, the last days it has been really cold at night. Since then my interior light no longer does. Reading lights with ignition goes on, so all 4 bulbs are changed. Reading lamps still go. Only the interior light no longer turns on. Does anyone have an idea? On the Omega Y22XE Caravan from 2000 everything is still original, i.e. radio etc. and via control unit also connected. Light went still a few days ago. No matter whether with key or remote control, it switched on and off with delay as it belongs. If I now pull out the light switch, then everything remains dark. Car is dry from inside and processes also free. Where is the delay regulated? In the lamp itself or where else? Presumably mine is defective. Or someone else’s idea or experience with it? Thanks in advance people!