My brake lights and rear turn signals were messed up recently because I replaced the housings with reproduction units (bad idea). And one of the tabs in the socket that the light bulb touches which controls the turn signals was really flimsy and kept touching ground. Surprisingly this did not cause a short or blow a fuse like it should have, but it made my rear lights go haywire!
My instrument cluster would light up every time I hit the brakes. And if I turned the right turn signal on, both rear lights would light up as well as the instrument cluster.
I would say to check all of the ground wires and make sure everything is ok inside the light bulb sockets.