94greenFormula

Hello all. I have just bought a 94 formula and I put a Pionner Head in it and bought some speakers for the door. But I noticed after installing my head that now only the Rear hatch speakers and the door speakers only work. The ones in the rear Sail panels do nothing now? Now I do not know a hole lot about Stereo work. I know mostly about rebuilding engines and stuff like that. This head I have had for alwhile I forget what modle it is. It came from my 91 bird in which it worked fine. Now I saw on the front that it said 50 w x 4 channels. Now I gussing that the channels are the a mout of speakers that the head can handle? If so what are my options for geting all 3 sets of speakers working because I have speakers already from past cars to put in or is it just not posable to do? Thanks