parking brake light

i have a 1988 chevy burb 4wd it just turned over 200,000 miles. When it began the parking brake would turn on if i pushed the brake down hard. Now its just on all the time, even when im driving down the road wether or not im pushing on the brakes or not, it still brakes ok but its a little weaker, I'm taking it into the my schools auto shop to see if its throwing any errors, but i wanted to see if anyone had any ideas in the mean time.

Check the park brake adjustment and the park brake switch for being loose.
The Red brake warning lamp also is connected to the low fluid sensor or the pressure differential switch to warn you of a fluid leak