My 02 town and country has stock everything and all of a sudden going over bumps all four speakers started going out and now there is no sound only sometimes. The radio itself stays on and keeps playing whether it's a cd playing or cassette but the speakers make a crackling and constantly go out. I took the radio out to check harness it wasn't loose or anything. Do you think it could be a bad radio or maybe a short. Would a short cause all four speakers to go out?