Question for the learned peoples here.

I have a TJ AWD.... with stock radio/cd head unit and stock speakers.
Everything used to work fine....

But now the FM radio gets no reception (none at all). The AM works fine, CD's work fine, the antenna goes up and down fine. But no FM signal.

Havent pulled things apart yet, but am looking at for ideas.

Is the antenna required for AM signal? If not, then best theory i've got might be the antenna cable has come loose from the antenna itself?

I'm pretty sure that AM and FM use the same aerial, just unplug the aerial and see if you get AM, if you do it aerial problem. If you lose AM all together then it a stuff head unit.