Wiring! Lights! Argh!

Well, my tailights aren't working, neither are my dash-lights. I checked the tail-light fuse and it was blown, put another in and turned on the lights and it blew that one right away. What is causing this? Also, can't find a fuse that corresponds with the dash-lights, so would they be on the same circuit as the taillights by chance? Also, if it helps diagnose, i just put in a new stereo head unit. Pioneer MP435U

you have a short to ground in your tail lights find it, get a volt or ohm meter, depending on how you want to check it, and wiring diagram and find it, and for your dash i have no idea