Clock won't display unless i press and hold 6
 

So this problem started up last week sometime. Didn't even notice until I was driving home one night but the clock display doesn't display anything. Changing songs, radio station nothing comes up. If i hold 6/shuffle the song number is displayed, the clock returns and after a few minutes the display goes blank again.

I looked through the manual, and did a search on here but couldn't find anything.

Anybody have an idea what might be causing this? If it just didn't work I'd figure a fuse but the fact that i can make the display light up has me confused.

Thanks,
Marchy

edit: in case you don't read my sig, its a 99 ranger xlt.

So I fixed the issue by holding the 5 button, didn't drive the truck over the weekend and its back. All other lights on the radio work and again the clock come back for a bit when I hold 5. Any idea?