1999 Intrepid, Replacing Factory Stereo

Hello all, I have a 1999 Dodge Intrepid.  I'm trying to replace the factory stereo with a pioneer cd player.  i have all the wires connected properly. When I turn on the ignition switch, the pioneer lights up but  I have no sound.  The new cd player works because I hooked up a speaker to all of the speaker wires one at a time to see if the new player was working and I can get sound that way.  The car doesn't have the infinty system in it so I am stumped. Does this car have a factory amp that is keeping the sound from reaching the speakers, and if so, where is it so I can by-pass it?  Any advice will be appreaciated.  Thanks in advance. 

Thank you very much.  The diagram solved the problem.  The people at Chrysler are a little slow.  They couldn't answer  the question if it had a amp or not.  Thanks again.