After unhooking my amp and subs one day, all I would hear from the back speakers was this crackling noise that persisted even after powering off the car. If left overnight, the battery would be completely drained by morning. I resolved this temporarily by removing both radio fuses and disconnecting the back speakers, which kinda leaves me without sound. My friend, who's quite good with electronics, unhooked the radio and tested it along with the back speakers... both were fine. I have the standard deck, with cd player. I really don't know much about cars, and it sucks driving around with no radio to ease the road rage. Any help would be greatly appreciated!

Do you have any amplifiers in your system?
If so check the remote wire (usually blue) may be exedentaly connectet to constant+. That would cause the amp be constantly on and drain the batt...