Car Stereos: Only subs work on the CD function, alpine cda, alpine head unit

Question
Hey I replaced a older and cheaper head unit with an alpine cda-105. I have done self installs many times in my life and never had a problem. So everything works great until I put a cd, at that time all factory speakers stop working and my subs start trying to play all frequency's. Any suggestions?

Answer
Hi Harley,

Sounds like your vehicle is equipped with a factory amplifier.  This is more common than many people realize. Here's what to do:

Disconnect whatever you have connected to the BLUE wire at the back of the Alpine head unit.  Re-connect it to the BLUE/WHITE wire instead.  Your amplifier's remote wire should already be attached to the blue/white output; that's okay.  Just add the other wire as well.  

The explanation:  the factory amplifier has its own "remote" activation wire, just like the after-market amp.  Many adapter harnesses use a blue wire for the amp's activation wire, but the blue wire on your Alpine deck is meant for a power antenna--it only works when the tuner is selected.  Switching the activation wire to the blue/white will turn the factory amp on whenever the head unit is on.

This problem is most common in Chrysler/Dodge/Jeep vehicles, but it happens in others as well.

Hope this helps!

Brian