I just installed a pioneer HU in a friend's car. Everything works, except that the front left and back left speakers sound muddy, while the right speakers sound perfectly fine. Speakers are running off the deck. I checked the wiring for the left speakers and all the wires are matched correctly.
I don't know the model number right now.
Never had this kind of problem. I was thinking that maybe the wiring on the speakers might be off, but it seems like a coincidence that this problem is with the left side only and not the right.
Anyone have an idea of what might be wrong?