try disconnecting the battery. I did that and everything went back to normal. the only thing i did was take out the brake switch by the e-brake (requires you to remove some of the center console components and the shift lever), cleaned it, regressed it a bit, plugged it back in, disconnected the battery and wahlah. i didn't spend a dime on replacing any sensors. (knock on wood) see if that works. that should reset everything. in rare occasions there's a solenoid on the transmission that doesn't enable you to get out of park.