Dash illumination lights not working?

Hello,

my brother has a 95 XJ that we just put a pioneer deck into. the radio and lights worked fine for the first couple of days, but now the dash illumination lights quit working, but the radio still works fine. Are the dash lights tied into the radio harness in any way? any ideas where there could be a loose connection causing the dash lights not to work? i already checked the fuses and they are fine.

Im stumped and any help is appreciated!

The radio harness does have a dash illumination line going to it iirc - it should be a light blue wire with a red stripe (illumination) or orange (dimmer, which I think is the one you want. Not sure.) See http://www.the12volt.com/installbay/stereodetail/1210.html for a full wire color code reference.