Hello, need some help. I recently changed a flat battery with a new one and since then the radio, boot light and the cabin light are not working. The rest of the electricals are working fine and the car is running well.The mechanic checked all the fuses, relaysand were all OK. He suggested to change a peculiar looking ? fuse at the fuse box near the driver's door. The ? fuse is black in colour and has a arrow sign on the top. It fits at the top of the fuse box near the drivers door. I tried to repalce it and basically lost it while trying to find a replacement. The car is running well without it. All the electricals are working as before, except the radio, boot light and the cabin light. Can some one please tell me the function of the black thing I have lost and what does it do? Thank You very much.

 

I think that little black plug is the shipping plug. If it is put in upside down, it keeps the radio, dome lights, etc., from draining the battery during the long boat ride from Korea. Put it in right side up and all that stuff is connected. If you've lost yours, try going to a salvage yard and getting one from a wrecked Hyundai.

The plug I'm talking about is the black one on the right side of this Elantra fuse box: