ABS/Brake light on 1993 GMC Vandura 2500

When vehicle is running the dash brake light is on, but when you turn it off the dash brake light goes off and the ABS light comes on and stays on. I have never had an indicator light be on when the keys are in my pocket. Found the battery drained 24 hrs later. Any Ideas? Brake fluid good and full.

Asked by for the 1993 GMC Vandura 2500
This could be a defective ignition switch. I have actually heard about this form a GM tech. So, need to check and make sure that there is nothing still energized with the key out.
Would that also lead to the dash brake light being on when the engine is running?