Why would Only 1 brake light work and thats the one in the rear window any suggestion?
Check the fuses, as well as the bulbs. If all that is good AND your system uses the same light (Brake Light) for the turn signal, then check the turn signal switch as well (the brake light lead passes through the turn signal switch). If that is all good, or it is a different system, then check the wire leads running into the rear section; most have plugs that could have become disconnected.