Brake lights on when head lights on
 

I have a 1999 chevy express conversion van and when i turn the head lights on the brake lights come on to, pulled the brake light switch and they still come on. Any ideas why? Thank You
Update now i have no brake lights when headlights are on, any ideas? Brake lights work when headlights are off.

you're sure they're not tail lights?

all 4 lights should light when lights are turned on only 2 light up and they are bright, and when i step on the brake they dont change. turn lights off then step on brake they light up

Check all the wiring and sockets for the brake lights. There is a short somewhere.