The first thing I would check is the park brake switch, which is mounted on the park brake pedal bracket. The pedal pushes on the switch when the park brake is not engaged. If the switch is loose on its mounting or is not set up tight enough against the pedal, the switch could be simulating a "park brake on" situation. I believe an intermittantly shorting park brake switch wire would also cause this problem .
It could be that you're low on brake fluid and when you go up a hill, it gets low enough near teh sensor to trigger the light. The parking brake light doubles as an idiot light for the brake system.
Definitely the brake fluid level. As the pads wear down the fluid level drops to compensate by pushing the piston/wheel cylinder out. Probably a good thing to look at them.
A forum community dedicated to the Ford Taurus and SHO models, Mercury Sable and Lincoln MKS. Join the discussions on EcoBoost, aftermarket performance, and more!