Brake lights are always on while the car is running - 1990 Toyota Corolla

You say "when the car is running" but I assume that you mean whenever the ignition switch is on. I think you have a partial short in the brake switch wiring somewhere. I say partial because when you push the brake pedal, the lights brighten because you now have a good ground. Probably, the wires have worn through the insulation somewhere and are toughing the body metal. Move the wires around a bit and see if you can get it to stop. If so, use electrical tape to renew the insulation.

Yes, whenever the ignition is on :) good clarification. Any idea where to look for the brake switch wiring? Would it be under the hood, or under the dash?