Problem with Interior lights always on

I was reading a previos post regarding the same problem but found nothing usefull.Ok I have a 1984 turbo model, this morning I noticed my interior lights were on. I checked that all doors and hatch were closed and the lights were still on. The only way I can turn them off is by turning the switch off by the glovebox. Any ideas on what the problem might be?

First thing I would check is the door ajar sensors. Put a multi meter to them and see if they turn on and off when the door is closed.