I got the AVIC F700Bt installed in my 05 F-150 last night and all is well (haven't even got to the PAC unit yet) except the sound is tinny and low tones sound distorted at all volume levels. Is anyone familiar with this issue? I am pretty sure the factory sub is not working either. I have tried adjusting the EQ, bass settings, subwoofer settings and it doesn't have any affect. I even unplugged the subwoofer harness and it sounds the same. Is it possilbe I have a bad ground? The factory stereo did not have this issue. I am posting to AVIC 411 and here so hopefully someone can give me some direction on what I should check or advise on how to troubleshoot this issue. I am worried I have a bad unit. Please help!

Thanks,
WFR