headunit help

I have a sony headunit and I am hooking up my amp but the amp only turns on when the radio playing and not when a cd is in. The speakers play constantly but the sub only comes on when the input is on radio.

Is there a setting on the headunit, a wiring problem, or would you assume the headunit is broken?

Sounds like you have the power antenna lead turning on the amp. There should be a different lead for amp turn on. Look at the owners manual for your deck, it might be downloadable from the sony site.