I have a 99 f150 4.6 witch has had slow battery drain for some time which has recently sped up perhaps due to the toll it has taken on the 2 year old battery. After jumpstarting the other day I noticed crackling in the backseat driver side speaker, after removing keys the crackling continued.. I then removed the radio fuse and it still continued until I removed the ground from the battery. removing the door panel and inspecting the wiring is next but I thought I would see what others would suggest during this process.

Thanks in advance.