When i put in my subs and speakers, deck etc i blew a fuse that took out my brake lights, although i didnt lose power to my rear speakers. Thats kinda weird. Check your wiring back there for the speakers, and have a look to see if you blew a fuse for the brake lights. This fuse is located under the hood.
Do you still have power to your dash lights? Like the spedo etc? When i lost my brake lights i also lost those lights aswell.
