brake light
 

ok so i have been doing some repairs on my 1990 3/4 pickup and just replaced the map sensor, service engine soon indicator has gone off :D, which makes me happy, now one thing i want to figure out is that the brake light indicator has been on since i bought the truck and stays one, the one that has the following (P)(I) and brake on it, what should i check for to get this light to shut off?

gene