2004 F-150 factory speaker prob.

A friend and myself recently wired a kenwood satellite radio and reciever into his 2004 F-150, we tried to splice into the factory head unit, acc, and ground wires to runteh satellite HU. But (I belive because the reciever draws it's power from the HU) the kenwood HU would not continuiously play, it would just turn on make a skipping noise then turn off. So we spliced the wires into the positive and ground from an unused cigarette lighter in the dash. After that we pigtailed the seaker wires from the kenwood HU into the factory HU wires but to no prevail, we instead used an FM modulator. Now, he has lost the front left speaker (drivers side) it seems like it turns on and off whenever it feels like it. Any suggestions as to where or what this might be? ANY HELP will be appreciated, Thanks-clinton