Fuse box

Hello everyone,

please find at the following URL a photo of the fuse box of my 79 Vette. Can someone tell me the use of that free plug at the end of the orange wire (that should evidently be connected to that big black part to the right). I got my car a few months ago and no part of the light group inside is working. I'm interested to make it work but I wouldn't want to fry anything. Air is not working either (no belt on the compressor). Thanks !
http://www.VetteRegistry.net/member_uploads/4001_4100/4004/fuse_box.jpg

The big black thing is just the seatbelt warning buzzer. I believe it also warns of the key in the ignition and the door open. Probably the only reason it is unplugged is because it's annoying. What lights are you talking about not working? Instrument lights? Dome light? If dome lights, check the cigarette lighter, on the same fuse. Alarm is also on that fuse, If a problem with the alarm, maybe previous owner pulled the fuse like he disconnected the buzzer. Mike

Back again. Just went back and looked at your picture. The dome light fuse is there. It's the one right above the disconnected plug. 20 amp. Check it, might be that simple! Mike

Thanks a lot Mike. I'll make some tests during the week-end. I was talking of dome lights. I find it very interesting to ask questions and get answers so fast. That C3VR site is very very useful. Save the wave ! Thanks again !

Roger