'99 Grand Prix - BIG audio problem

OK...so in my grand prix i have a Pioneer DEH-P670 deck, a 120W 2-channel amplifier (for the 6x9's), 5 1/4" 2-way Kenwoods in front (stock tweeters) and 4-way Pioneer 6x9's in the back...the front speakers are hooked up with the stock wireing and everything, nothing has been changed. The rear speakers are hooked up to the amp the way they are supose to be. Everything was working and sounding great for about 2 weeks and then out of no where my front left speaker started scratching when it was turned up past like 15 (which is very low) and then shortly after the right one started doing it also. Before i knew it they were not working all together. Now i can change what works adjusting the balance and fade. If i put it exactly in the middle then the rear 6x9's work fine and there is no sound from the front. if i move it to the front middle then the front speakers work fine. If i move it anywhere else twords the front they get scrachy again...this makes no sense to me at all. I have even tried connecting my friends deck to see if that was the problem and the same thing occured. If ANYBODY can help me i would be VERY happy...thanks

Did your car come with the factory Bose system? If so, the factory amp may be arguing with your new set up. Also, when wiring your speakers, did you make sure you had them wired correctly? Reversing polarity on the speakers will cause the problems you are describing.

Did your car come with the factory Bose system? If so, the factory amp may be arguing with your new set up. Also, when wiring your speakers, did you make sure you had them wired correctly? Reversing polarity on the speakers will cause the problems you are describing.

No i do not have the factory Bose system. I am 95% sure i did it correctly. and why would they start doing that after a little while, i would think if it was wrong it would do it right away after i hooked them up. still, how can i check just to make sure they are correct?

What happens is the reversed polarity screws up the voice coils over time, and that's why it didn't start right away. Check a factory wiring diagram to be sure you have the feed wire hooked to the speaker + terminal, and the return wire hooked to the speaker - terminal on both sides.

oh ok i c, well say that is the problem. will they go back to normal when i switch them around to the correct way?