The tail lights on my 85 240 sedan are acting weird. When you depress the brake pedal with no headlights on the brake lights come on,kinda dim but are there. When the headlights are on the tail lights illuminate very brightly(almost as I would expect the brakes to be)but the brake lights don't work. I would expect the tail lights to be kind of dim but the brake lights to be much brighter. Any ideas or suggestions would be appreciated.