Brake light is dimly lit

I have a 1991 Toyota 4wd pickup. 3.0 engine with 170,000 miles. The brake light has recently started coming on but is dimly lit. Not like when you pull the emergency brake or if the brake fluid is low. Fluid level is fine. Brakes work good. Only problem is when braking feels like the rotors need to be turned. Any idea what might be causing the light to come on? Thanks for your help.