battery question

when i'm sitting with the engine off and the battery running, sometimes the interior light comes on for a minute or two, then goes off by itself.

it's only started recently, could it maybe be a fuse or something?

Your statement isn't very clear... is this right after you shut your car off and haven't opend the door yet or what. When i turn my car off and the key to the off position and pull it out... the light comes on and stays on for i think 20-30 seconds... this is normal... also when you open and close your door, it will stay on for a minute after you close the door..

no, it's maybe after the car's been off for a couple of minutes. the light comes on after the car is off, and stays on for maybe 15-20 seconds, then goes off. then comes back on by itself if the battery is running.

what year is your car?

'97

My 96 Cav LS does the same thing (I noticed at more than a few occasions) so your problem is not isolated.

I would look at the door chime module, as it also controls the delayed shut off of the interior lights and is what turns tehm on when you open the door. The other thing that could be a problem is your headlight/multifunction switch could be going bad and is "bleeding" power to the interior lights.