Electrical Brake lights on with headlights

Hey everybody, I have a brake light issue with my 1990 5.0 lx 5 speed. During the day with my headlights and running lights off, my brake lights work as the should when I press the brake pedal, and turn off when I release it. When I turn on my parking lights and/or headlights my brake lights stay on, doesn't change if I tap the brake pedal. When I push in the clutch everything returns to normal and the brake lights go out. While having the clutch pedal pressed if I touch the brake pedal the brake lights work as they should. I hope all that makes sense to someone. I'm new to the site so bear with me please, thanks for the help in advance.
 
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