Stange problem

I am installing a radio out of a 1999 Dodge Caravan in my Kelmark kit car.  I got the connectors that pug into the back ,there are (2) seven wire connectors my problem is with one wire that is suppose to be illumination I don't know where to hook it up too ,I thought it should go to the headlight switch ? Is it even needed as the led display comes on anyway when I turn the radio on. When I hooked that illumination wire to the headlight switch and turned the headlights on the display went out so I quess I don't know where it goes.  Anybody  know?Thanks,Rick Phillips

The illumination wire is NOT needed for the radio to function properly

Some decks are equipped with a wire for dimming the display at night.  Generally, you splice it in with the headlight switch wire so when the headlights come on the deck will dim.  Its not necessary for the deck to work, however.-Matt