I just picked up my car from the Audio shop and had two subs added to the bose system.

I got the special box so the stereo only comes on when the stereo is on instead of on ignitiion. I also had the LOC added so the subs are running off RCA which are spliced into the rear speaker wire.

I am not sure what is going on but I got out of the car and was moving some stuff in the trunk and the subs one from quiet to real loud then off.

 

Sounds like a wire shorted out.

 

I wouldnt say a shorted wire, but def a wiring problem. If the shop installed it correctly it will turn on and off as stock, but would also be seperate from the Bose system. Take it back and get them to fix it. But make sure they do it for free since they screwed it up the first time.