2003 Mazda Protege, Factory Stereo broke

I was helping a friend of mine out by hooking up his amp and sub to his factory stereo. its a 2003 Mazda Protege. hooked all the power and every thing up and the last thing was to splice off of the rear speakers and plug in to the speaker level input on the amp. when we turned the car on after that there was no sound comming out of the speakers...........none of them...............and even after wiring it back up to its original state there stilll isnt anything. i have tryed looking for a fuse for an amp for the factory speakers, and ive reset the cpu and still nothing,,,,,,,,,,,,,,,,,,,,,,,is there something im missing,,,,,,,,,,,,someone please................thanks,

Ian

yeh, it all works fine. and it was working fine until i cut the lines. the splices are clean and solid. i dont know why it would do this. i talked to someone at the dealership and they said that the fuse in the radio might have blown, but i have to take appart his entire dash to get to that. and if thats not it that i have no idea what could be the problem,,,,,,,,,,but if the fuse is blown wouldnt the entire stereo go out not just the speaker outputs.

Could be the fuse, yes.  Did you disconnect the battery before you cut into the system?  If you momentarily shorted out the speaker wires (by, for example, cutting through both positive and negative at the same time) the internal amps could have shut down (if the battery was connected.)  Speaker leads in OEM systems often have voltages running throught hem that have nothing to do with the sound, especially if the factory radio has a built-in clock or is interfaced with the car's security system or other electronics.  If the radio internal amps have shut down, there is probably a reset switch inside the head unit somewhere.  Your dealer may know.

Also, if the car is still under warranty, what you did will almost certainly void the warranty on the stereo and maybe on the entire electrical system, unless you have a REALLY sympathetic dealer.  Ask them.