What system do you have? Navigation or Standard and do you have DSP.

I have a spare amp that worked with my system.... which is navigation - no dsp.

In my system the head unit up front is just a monitor. It actually has the head unit "brains -- radio module" back under the spare tire which then goes to an amp in the left rear quarter panel. So if you have a similar system it could be either the amp or the radio module.