Got this 97 Civic LX, AM/FM (no cassette) but there is an OEM Single Disc CD-PLAYER next to the cup holders (stupid!!!). anyway, on the AM/FM/Clock unit, there is an LED above the "CLOCK" button and to the right of "6" button. It is shown in the Owner's manual, but I coudn't find it's meaning. It never came ON though. What is it???