I've got an early 2000s CIJ Fender Jaguar bass, all stock. It features an active passive circuit that is powered by a 9v battery. All was going well until last weekend I showed up to band practice and was greeted with an ear piercing shrieking coming from my amp. After some trial and error I narrowed the issue down to my bass (whether it was in active OR passive mode). What seemed so strange about this to me was that upon removing the 9v battery and switching to passive mode (bass is silent when in active without a battery, was always like this) the shrieking stopped and I could play it like normal. When I got home I tried a new battery but no luck. I haven't attempted any mods, dropped the bass (to my knowledge) or even opened the thing up in the past few months. I'm stumped! Any suggestions are welcome, please help this poor fool!